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TRADE PREAMBLES AND SPECIFICATIONS
GENERALLY
A. MATERIALS GENERALLY
All materials used in the works shall be new and of the qualities and kinds specified
herein and equal to approved samples. Deliveries shall be made sufficiently in
advance to enable samples to be taken and tested if required. No materials shall be
used until approved and all materials which are not approved or which are damaged,
contaminated or have deteriorated in any way do not comply with the requirements
of this Specification shall be rejected and shall be immediately removed from the Site
at the Contractor’s expense.
B. KENYA STANDARDS AND BRITISH STANDARDS
All materials used in the works for which a Kenya Standard Specification is published
shall conform to latest Edition thereof in every way. Materials for which no Kenya
Standard exists but which are covered by a British Standard shall conform to the latest
Edition of that Standard.
Where materials are covered by both a Kenya Standard and British Standard the Kenya
Standard will override the British Standard where inconsistencies occur.
The Architect reserves the right to demand that the Contractor obtain at his own expense a
certificate in respect of any material to state that it is in accordance with a Kenya or
British Standard Specification.
C. MATERIALS FOR WHICH THERE IS NO STANDARD
All materials used in the work for which no Kenya or British Standard Specification has
been published shall be the best of their respective kinds and of a standard to the
satisfaction of the Architect. The quality of such materials shall be generally of a
standard equal to those for which there is a Kenya or British Standard Specification.
D. ALTERNATIVES TO PROPRIETARY BRANDS
Where materials are specified by their proprietary names or where fittings are specified
by catalogue numbers, or descriptions, the Contractor may offer materials or fittings of
alternative manufacture which are of equal quality. Such alternatives must be approved
before being used in the works and the Contractor shall allow for this, but prior to
tendering he may submit to the Architect for approval, the names of any suppliers or
manufacturers whose products he intends to use, together with catalogue numbers, and
descriptions and/or samples but the decision of the Architect will be final.
E. MEASURING AND TESTING EQUIPMENT
The Contractor shall provide the following equipment for carrying out measuring and
control tests on the Site and maintain in full working order: -
1. Straight edges 2 metres and 4 metres long for testing the accuracy of the finished
concrete.
2. A glass graduated cylinder for use in the silt test for organic impurities in the sand.
3. Slump test apparatus.
4. 150mm Steel cube moulds with base plates and tamping rods to B.S. 1881. Two 30
metre steel tapes.
5. One dumpy or quickest level and staff.
A. PRICING NOTES GENERALLY
a. The rates set down by the Contractor against each item shall unless
otherwise expressly provided to the contrary, or unless there is a separate
item for extra labour, cutting or waste, be held to include for waste on
materials, carriage, and cartage, carrying in and return of empties, hoisting,
setting, fitting and fixing in position, marking all other labours and
everything else necessary for the proper completion of each item and or
establishment charges and profit.
b. Throughout the Bills of Quantities generally no mention is made of heights for
hoisting and all prices must include for hoisting and fixing at any level
within the limit shown on the drawings or include in the general description
unless a specific level stated.
c. The Contractor shall be deemed to have made allowance in his rates
generally to cover items of Preliminaries, expenses in connection with
Prime Cost Sums or other items if these have not been priced against the
respective items.
EXCAVATION
B. INSPECTION OF SITE
The Contractor is deemed to have visited the site and to have ascertained the nature
of the soil and sub-soils to be excavated. No claim will be allowed on account of
these being of a different nature from that for which he has allowed in his prices.
C. PROCEDURE
The excavations and fillings shall be carried out in such a manner and order as the
Architect may direct.
D. EXISTING TREES AND SHRUBS
Cut down and remove shrubs and trees as directed. No shrubs, trees, plants, etc. shall
be removed except as directed by the Architect and the contractor shall be held
responsible for any damage caused by the building operations to those shrubs, trees,
etc., not so directed to be removed.
E. SITE CLEARANCE
All grass, vegetable matter etc., must be removed or burned on site at the commencement of
the Contract over areas as directed by the Architect.
A. WHITE ANT – INSPECTION TREATMENT
The Contractor must destroy any white ants’ nest found within the perimeter of the
buildings and within a distance of 20 metres from the buildings externally and take out
and destroy Queen Ants, impregnate holes and tunnels with approved insecticide and
back-fill with hard material well rammed and consolidated.
B. EXCAVATION
The excavations are to be executed to the widths shown on the Drawings, and to the
depths below existing ground level as directed by the Architect in order to obtain
satisfactory foundation. If the Contractor excavates to any widths or depths greater than
those shown on the drawings or as instructed by the Architect he shall at his own
expense fill in such widths or depths of excavation beyond that instructed or shown with
concrete as specified by the Architect.
I. Level and ram bottoms of all excavations to receive concrete form
stepping if necessary or directed to allow for sloping ground and well water
excavations before pouring concrete.
II. The Contractor shall report to the Architect when secure bottoms to the
excavations have been obtained. Any concrete or other work executed before the
excavations have been inspected and approved shall, if so directed, be removed and
new work substituted after the excavations have been approved all at the
contractor’s expense.
C. ROCK
i) Rock is defined as any material met with in the excavation which is of
such size or position that it can only be removed by means of wedges,
compressed air plant, other special plant or explosives and the
Architect’s opinion shall be final. Excavation in any material such
as soft coral, hard murram, stiff clay or similar materials which in the
opinion of the Architect can reasonably be removed by pick,
traxcavator or similar means will be deemed to be included in the
prices for normal excavation.
ii) All materials classified as rock may, if approved by the Architects be
used as hardcore filling and the measured quantities of imported filling
will be adjusted accordingly. All rock so used must be broken to the
required size as hereafter described before being so used.
D. BLASTING
Blasting will only be allowed with the written permission of the Architect. All blasting
operations shall be carried out at the sole risk and cost of the contractor and in
accordance with any Government regulations in force for the time being, and any special
regulations laid down by the Architect governing the use and storage of explosives.
E. BURROW PITS
Burrow pits will only be allowed to be opened up on site at the written permission of the
Architect.
A. HARDCORE FILLING (OTHER THAN CORAL OBTAINED FROM
EXCAVATIONS)
Hardcore for filling under floors, etc., shall be good hard stone of coral, ballast or quarry
waste (not soft coral) to the approval of the Architect broken to pass not greater than
150mm ring or to be 75% of the finished thickness of the layers being compacted
whichever is the lesser and graded to contain sufficient smaller pieces to fill all voids so
that it can be thoroughly compacted. The filling is to be in layers each of a consolidated
thickness not exceeding 225mm and well watered and compacted by hand or mechanical
tampers. The top surface of the hardcore shall be levelled or graded to falls as required
and blinded with a 75m layer of similar material finely crushed and well rolled and
watered immediately before concrete is laid.
B. FILLING OBTAINED FROM THE EXCAVATIONS
Filling obtained from surplus excavated materials is to be free from all weeds, roots,
vegetable or other unsuitable materials and is to be filled in layers each of not more than
225mm finished thickness. Each layer to be well watered and consolidated before the
subsequent layer is filled in.
C. MATERIALS FOUND IN THE EXCAVATIONS
No sand, aggregate or other material found in the excavations is to be used in the works
without written permission of the Architect.
D. POLYTHENE MEMBRANE
(i) Where the joints occur there is to be a minimum of 300mm welted lap or
joint made with approved tapes.
(ii) The Contractor shall ensure that the membrane will not be pierced during
the laying and concreting of sub-floors
E. INSECTICIDE TREATMENT
(i) Insecticide treatment shall be “Aldrex” 48 or “Dieldrex” 18 (to be obtained
from Kenya Shell Limited. P.O. Box 43561, Nairobi.) applied in accordance
with the Manufacturer’s printed instructions or other equal and approved
treatment.
(ii) After the hardcore filling has been prepared the whole surface including
the top surface of foundation walling shall be similarly treated before
concrete slabs are poured. The treatment shall extend 1.5 metres beyond the
external wall faces of the building.
F. PRICING NOTES
Prices shall include for excavating in any material encountered unless specifically measured.
Excavation and disposal of soil are measured net before excavation, filling is measured net
after consolidation.
Prices shall include for handling, etc., of extra bulk after excavating, or before consolidating,
any extra excavation required for formwork or planking and strutting, circular work,
grubbing up any old drains, roots, etc., that may be encountered and for well watering
bottoms before laying concrete unless specifically measured.
Prices for returning, filling and ramming or carting away are to include for
removing the excavated materials to temporary heaps or dumps, etc., as required
or made necessary by the progress of the works, site conditions, etc., and for any
re-excavating, re-handling and transporting from such heaps or dumps. All
excavated material has been either returned, filled in and rammed or carted away
and therefore the rates for these items must include for all costs involved in
getting this material to its final position.
The thickness of all soil, hardcore etc., beds given herein is thickness after
consolidation.
The term formation level used in descriptions of work means the level after general excavation
to reduce levels of Site or where there is no such bulk excavation the level after removal of
surface soil.
CONCRETE
A. DESIGNATION OF CONCRETE MIXES
The various mixes of concrete are designated in the subsequent measured items
by the following criteria:-
Nominal mixes: By the weight proportions of whole bags of ordinary Portland
cement to fine and coarse aggregate and by the maximum size of coarse
aggregate. The Contractor shall regularly submit details giving specific
gravities and moisture content of aggregates.
B. TAMPING
The term “tamping” as used herein in conjunction with the phrase treating surfaces of
unset concrete” shall mean the final compaction and surface finish to be applied to unset
concrete beds, or the like, with steel shod beam tamper, either manually or mechanically
operated unless otherwise stated. The resulting surface finish shall have a slightly ribbed
appearance.
C. KEYING
The term“Keying” as used herein in conjunction with the phrase “treating surfaces of
unset concrete” shall mean the preparation of beds, or the like, to receive insitu pavings
by raking with a standard horticultural rake whilst the concrete is still green and when the
concrete is set and cured, protecting the raked surfaces with a layer of clean sand and
removing the sand immediately before the insitu paving is laid.
D. PRECAST CONCRETE UNITS
Unless otherwise described in the measured items, precast concrete units are deemed to
be basically rectangular in cross section and rough on exposed faces. Reinforcement bars
shall have hooked ends. Bedding and pointing mortar shall be either cement or
cement lime mortar, as appropriate, and units shall be deemed to be fixed by hoisting,
bedding and building in unless otherwise described.
Nominally non-reinforced units may contain any reinforcement the Contractor may wish
to Introduce for handling purposes.
GENERALLY
A. STANDARDS
The whole of the concrete work and testing thereof shall comply with British Standard
Code of Practice No. 114 and with the subsequent clauses of this Document and shall
be carried out in strict accordance with the working drawings and instructions of the
Architect and the Structural Engineer.
A competent person shall be employed whose first duty will be to supervise all stages in
the preparation and placing of the concrete. All cubes should be made and site tests
carried out under his direct supervision. This person shall also be responsible for keeping
an accurate record of the dates on which concrete is poured.
B. BAR BENDING SCHEDULES
The Structural Engineer will prepare and provide all necessary bar bending schedules
and explanatory details.
The Contractor shall check these bending schedules against the corresponding drawings
before any cutting or bending. Any discrepancies shall be reported to the Engineer.
The Contractor shall be responsible for any delays or additional work caused by his
failure to check the schedules.
MATERIALS
C. SAMPLES
Samples of all materials are to be submitted for approval of the Architect at least one
week before it is desired to commence deliveries. All condemned materials are to be
removed from the site within 24 hours.
D. CEMENT
Cement shall comply with Kenya Standard as follows:-
Portland cement - K.S. 02-21
Rapid hardening cement - K.S. 02-21
Sulphate resisting Portland cement shall comply with - B.S. 4027
Rapid hardening cement may be used in lieu of ordinary Portland cement only with the
prior approval of the Architect or Engineer, provided that all conditions applying to its
use are strictly observed. Any additional expense in connection with the use of such
cement shall be borne by the Contractor.
The use of high alumina cement will not be permitted. All cement shall be
delivered to the site in sealed bags bearing the mark of the manufacturer. Rebagged
cement, cement in plain bags and cement in torn bags will not be allowed on the site.
Each consignment of cement shall be accompanied by the manufacturer’s certificate
showing that a representative sample of the consignment has been tested and compiles
with the appropriate specification.
From time to time as requested by the Architect, copies of the cement manufacturer’s test
certificate shall be delivered to the Architect or his representative on the site promptly,
but such documents shall not preclude the Architect from rejecting any cement which
does not in every way comply with the specification.
Any cement, which has failed to pass the tests or has been damaged by water or
contaminated in any way on site, shall immediately be removed from the site.
A. AGGREGATES
Aggregates shall comply with British Standards as follows:-
Fine - B.S. 882 table 2 Zone
1 to 3 only.
Coarse - B.S. 882 graded
“All in” ballast - B.S. 882 graded
Granite - B.S. 1201 graded
B. AGGREGATE
Each type aggregate shall be obtained from one approved source, capable of
maintaining adequate supplies of consistently graded material throughout the
contract. Aggregates for exposed concrete shall be free from all impurities
likely to cause discolouration and shall be of consistent colour throughout the
work.
Fine aggregates and sand shall be clean, sharp, coarse, hard material and equal at
all times to the samples which shall be deposited with and approved by the
engineer. The caustic soda test for organic impurities shall show a colour not
deeper than that of the standard solution. The setting test for natural sand shall
be made after being allowed to settle for three hours the layer of silt deposit on
the coarse material shall not exceed 10%.
The contractor shall supply necessary equipment for the testing of fine
aggregate and sand for the use of the Engineer.
Coarse aggregates shall be hard , clean gravel or broken stone from approved
quarries and shall be free from earth, decomposed stone, and extraneous matter.
They shall conform to B.S. 882 and shall be “Graded Aggregate” 20mm to
5mm. Thin, elongated, friable, flaky or laminated pieces, mica or shale shall
only be present in such small quantities as not to affect adversely the strength
and durability of the concrete. The amount of fine particles occurring in a free
state or as loose adherent shall not exceed 1% when determined by the laboratory
sedimentation test. After twenty-four hours in water, a previously fried sample
shall not gain more than 10% in weight.
Each grade of aggregate shall be stored in the works in separate heaps so that
there shall be no possibility of any inter-mixing. Any materials which have
become inter-mixed shall be removed from the site forthwith by the Contractor.
If, in the opinion of the Engineer, the aggregate is dirty or adulterated in any
manner, it shall be wasted and or/ screened by the Contractor.
Graded samples of all types of aggregate each weighing 10Kg. Shall after
approval, be kept on site behind glass for visual checking of subsequent
deliveries for grading, shape, and where applicable, colour.
A. REINFORCEMENT
Reinforcement shall comply with the following standards: -
(a) Mild steel rod reinforcement shall be – K.S. 02-22
(b) High tensile steel reinforcement shall either be cold worked deformed steel
bars of circular octagonal section complying with B.S. 4461 or hot rolled
deformed high tensile bars having a guarantee minimum yield stress of
4200 kg/sq. cm (60,000 p.s.i) and other physical qualities in accordance
with B.S. 4449.
(c) Welded steel fabric reinforcement shall comply with B.S. 4483.
All reinforcement shall be in the “diameter” and metric range and the substitution of “square
twisted” or imperial range shall be allowed but only at no extra cost to the Employer.
The Contractor will be required to submit at his own expense certified test data of the
following characteristics; ultimate tensile stress, yield point stress, elongation, cold
bend test. Should such certificates not be submitted by the manufacturer, the
Contractor shall have the requisite tests made at his own expense at an independent
testing laboratory.
B. EXPANSION JOINTS – FILLERS AND SEALERS
(i) Filler shall be Flexcell” impregnated fibreboard joint filler.
Top edges of filler to be covered with plastic tapes as a bond-breaking
barrier prior to filling with sealer.
(ii) Sealers to be
a) “Pli-astic” grade 99 applied hot with a machine pourer as recommended by
the manufacturers. Prior to application surfaces to be treated with a brush coat of
Expandite No. 3 Primer. or
b) “Plastic joint” hand applied bitumen putty sealant prior to application
surfaces to be primed as last. or
c) “High duty” sealer cold applied to sealant. Porous
surfaces to be primed with Expandite No. 20 primer.
iii) The appropriate sealers are specified in the measured work hereafter and must all be
applied and used strictly in accordance with the manufacturers’ printed instructions.
A. WALL TIES
Wall ties shall be provided between all columns and walling and shall be of
galvanised mild steel strip 25mm wide x 450mm long.
B. WATER
Water shall be from the mains and kept free of any impurities and acid or alkaline
substances in suspension or in solution, and shall be stored in proper storage tanks
to the approval of the Architect.
C. STORAGE OF MATERIALS
Cement shall be kept dry and used in rotation of deliveries. If delivered in bags
these shall be stored off the ground in a well-ventilated and weatherproof shed used
exclusively for this purpose.
The shed is to be sufficiently large to contain a working stock and provided with
partitions or such other means as may be necessary to ensure the effectual separation
of the various consignments and type of cement. Stacking of cement in bags over a
height of ten bags will not be permitted. Cement may be delivered in bulk
containers provided additional suitable arrangements are made for bulk storage on
the approval of the Architect.
Aggregate shall be stored at mixer positions on drained concrete paved areas, with stout
dividing walls between different sizes and types of aggregates.
Reinforcement shall be stored by type, size and length either off the ground or on
clean surfaced areas, and shall be kept free from rust.
D. PROPORTIONS OF CONCRETE MIX
The quantity of cement shall be measured by weight and each batch of concrete is to
use one or more whole bags. The quantity of fine aggregate and coarse aggregate
shall be measured separately by weight-batching plant. Volume mixing will not be
permitted.
For grading test the Contractor shall supply and deliver at his own cost to the
Approved Testing Authority, samples of the aggregates which the Contractor
proposes to use, consisting of not less than 50 Kilograms weight in fine aggregate.
It is the Contractor’s responsibility to ensure that the subsequent deliveries of
aggregate conform to the grading analysis of the approved samples.
The proportions of materials to be used for the preliminary cube tests and subsequent
batching, shall be ascertained by calculation from the results of the aggregate
grading tests carried out by the Approved Testing Authority.
Preliminary concrete cubes shall be made by the Contractor on site as required by the
Engineer and tested by the Approved Testing Authority. As a result of these tests
definite weights of each material for batching shall be ascertained and agreed with
the Engineer. Thereafter these proportions shall be adhered to throughout the works
and may be varied only by the instructions given by the Engineer.
The weights of damp aggregate must be adjusted to take into account the weight of
water in the aggregates, and this in turn will affect the amount of water to be added
into the mix.
Throughout the carrying out of the Contract, “works Cube Tests” are to be made from
concrete drawn from newly laid concrete or concrete about to be placed in position,
such cubes being made when directed by the Engineer and in his presence. Such cubes
shall be made in 150mm cube steel or cast iron moulds and shall be marked and cured
strictly in accordance with the Appendices of the Code of Practice, and shall be
forwarded carriage paid in time for testing at the required age to the testing laboratory
approved by the Engineer.
Three cubes shall be made on each occasion, concrete for each cube being from a
different batch. Two cubes shall be forwarded in time for testing in twenty-eight days.
Each cube shall be marked with the date of casting and a distinctive reference number in
accordance with a system agreed by the Engineer.
A record shall be kept of the position from which the concrete for each set of cubes was
drawn, or to which it was about to be placed.
At least three sets of three cubes shall be cast during each week concrete is being cast
including sets of cubes for each quality of concrete used during the period, or at
frequency agreed by the Engineer.
Concrete is required to have the properties and give the strength Newtons per square
millimetres as follows:-
Class Mix Max. – size Max. water Min. crushing
of coarse cement ratio strength of
aggregate by weight works Test
Cubes in N/mm
7 days 28 days
30 1:1:2 20mm 0.50 21 81.50
25 1:1 ½:3 20mm 0.55 17.5 26.25
20 1:2:4 20mm 0.60 14 21
20 1:2:4 15mm 0.60 14 21
15 1:3:6 25mm 0.60 9 13.5
10 1:4:8 40mm 0.60 - -
The above properties and crushing strength are to be considered as the minimum
standard that will be accepted in the finished works.
If the strengths required in the table are not attained and maintained throughout the
carrying out the contract, the contractor will be required to increase the proportion
of cement or substitute aggregates at his own cost so as to give concrete which does
comply with the requirements of this clause.
The Contractor may be required to remove and replace at his own cost any concrete
which fails to attain the required strength as ascertained by the Works Cube Tests.
A. TESTING OF MATERIALS GENERALLY
The Contractor shall include in his tender prices for the execution of his part of operations
specified for testing herein and for supply of the requisite equipment.
After initial testing and approval of materials, it is the Contractor’s responsibility to
ensure and to demonstrate by the submission of further similar samples when so required
that subsequent deliveries conform to the quality, grading and (where applicable), colour
of the approved samples.
B TESTING OF CEMENT
Before work commences and when subsequently directed, the Contractor shall take 6 kg
samples, in accordance with B.S. 12 procedure, of cement and deliver these in tins
approved by the Engineer to an approved testing Laboratory for testing.
Each consignment of cement to the site, which shall be accompanied by the
manufacturer’s advice note and forwarded without delay to the Engineer, shall be
Delivered to the site at least 7 days before it is intended to be used in the works so that
the required tests may be carried out without retarding the progress of the works.
C. TESTING OF AGGREGATES
Before work commences and when subsequently instructed, the Contractor
Shall take the site samples, by methods given in B.S. 812, and deliver to the
approved Testing Authority for testing.
Such samples shall be submitted for approval at least 7 days before they are
intended to be used in the works.
D. TESTING OF REINFORCEMENT
Should the Engineer require reinforcement to be tested, it shall be tested at the
Contractor’s expenses and representative test pieces of such reinforcement to be
used in the works are to be sent to an approved laboratory for testing.
E. TESTING OF CONCRETE IN THE FIELD
Trial mixture
Prior to the commencement of the actual concrete work, the Contractor shall make, or
have made, Preliminary Test Cubes in accordance with B.S. 1881, using the aggregate
from which samples were taken for grading analyses. Six cubes are to be made on each
occasion, 3 for testing at 7 days and 3 for testing at 28 days. The cube strengths obtained
in the preliminary tests should show crushing strengths of at least 11/3 times the specified
works cube test strengths.
The Preliminary Test Cubes will be submitted to an approved Testing Authority for
crushing, and from the results of these tests, definite weights of each material for
batching will be ascertained, and agreed with the Engineer.
Thereafter these proportions shall be adhered to throughout the works, and may be varied
only by instructions form the Engineer.
If any of the concrete materials are to be varied or obtained from a different source, a
further set of Preliminary Cube Tests, using the proposed new materials, will be required.
Workability
The total water content in the mixture determines its consistency and once a consistency
of a trial mix has been approved it must remain constant throughout the Contract.
In order to help the concrete maintain the desired consistency the slump of an approved
trial mix shall be measured thereafter all mixes must give the slump as the approved
trial mix. The slump shall be determined by the test as described in B.S. 1881 Part 2. In
general, the approved slump shall be in the order of 75mm for hand compacted concrete
and 35mm for vibrated concrete. The slump test shall be made on concrete actually
being placed in the works at the commencement of each period of concrete placing and at
such other times as instructed.
Test specimens
The moulds for tests cubes shall be of metal and true to shape to give a 150mm cube and
shall be well oiled before filling. The mould shall be filled with concrete taken from that
actually placed in the works, the concrete being selected by the Engineer from a point as
near as possible to the position of placing. The filling of the moulds shall be done
immediately after the selection of the sample concrete and in such a way that the concrete
in the moulds be truly representative that in the works.
The concrete shall be placed in the moulds in three layers of equal thickness, each layer
being rammed with 25 strokes of a steel bar 40mm diameter, (or equivalent) weighing
2kg. If the concrete in the works is to be consolidated by mechanical vibration, the test
cube moulds shall be likewise vibrated after filling. Each cube shall be inscribed with
the date of manufacture and identification mark,.
A record shall be kept for each batch of cubes showing the position in the works, which
the concrete represents, the date of manufacture, the mixture and slump of the concrete,
particulars of the cement and aggregate used, a statement of whether or not the cubes
were vibrated and other information relating to the subsequent history of the cubes.
The moulds containing the test cubes shall be stored for 24 hours on the site in a damp
place free from vibration. At the end of this period the cubes shall be taken from the
moulds and stored in damp sand for 20 days if they are to be tested at 28 days, or for 4
days if they are to be tested at 7 days.
The Contractor shall be instructed about the dispatch of the cubes to an approved
laboratory and will pay all costs relating to the tests. A set of three cubes will be required
for not more than every 60 cubic metres of concrete placed in the works.
Quality of specimens
The test specimens shall have the compressive strength specified for each quality of
concrete at the appropriate age as given herein.
If the required strength is not obtained at 28 days, the Contractor will be required to cut
out and reconstruct all work represented by the test specimens at his own expense with
all dispatch, always provided that the Engineer may first permit further tests, at the
contractor’s expense, to prove the quality of the deposited concrete.
In the case of seven day Works Cube Tests providing unsatisfactory, the works may be
stopped, but shall not be liable to rejection until the result of the twenty eight day test
is known.
In the event of the results of the twenty eight day works Cube Tests proving
unsatisfactory, the work represented shall be immediately liable to rejection. The
contractor may, however, be given the option of cutting three specimens from the
completed work subject to the direction of the Engineer, and preparing therefrom test
cubes or cores which shall be sent to the Test Laboratory for testing as for Works Cubes
Tests.
Should the average strength of these specimens attain the specified minimum twenty
eight day strength, the work will, subject to the Engineer’s discretion, be accepted.
Alternatively, the Engineer may instruct the Contractor to make a loading test as
described hereinafter. The cost of all cutting, preparation of specimens, testing and
making good the portions of the structure affected, shall be borne by the Contractor. The
cost of all delays on site investigation of defects, cutting away and making good, shall
be entirely the Contractor’s responsibility.
A. DAMAGED OR UNSATISFACTORY MATERIALS
All materials, which have been damaged, contaminated or have deteriorated, or which do
not comply in any way with the requirement of the specification, shall be rejected and
shall be immediately removed from site.
No materials shall be stored or stacked on suspended floors without the Architect’s prior
approval.
Should any of the samples tested be found, in the opinion of the Engineer, in any respect
unsatisfactory or likely to produce unsound work, the whole consignment or load from
which samples were taken will be rejected, and the Contractor shall forthwith remove it
from site. Notwithstanding that any sample of the material may have passed the test,
the Engineer may later reject such consignment or loads if he shall decide that the quality
has deteriorated.
The Contractor at his own expense shall remove from the site, without delay, all rejected
material. Any delay caused by such rejection will not in any way relieve the Contractor
from his responsibility with regard to the completion within the time limit (s) specified.
Any bag of cement that is opened shall be used on the same day or be discarded from
the work.
B. COMPOSITE SUSPENDED SLABS
Concrete hollow pots
Concrete hollow pots for use in the composition floor slabs are to be of the sizes required
as shown on the drawings and with 25mm wall thickness and are to be true to shape, free
from cracks or distortion of adequate strength to support the concrete during placing and
consolidation by vibration. Stock are to be manufactured in accordance with the
procedure specified in B.S. 2028 and to be of mix not weaker than 1:4:8 cement: sand:
aggregate using maximum 10mm size aggregate.
Concrete hollow pots are to be cured for at least 28 days before use on the site. During
the first seven days of curing, pots are to be kept permanently damp and protected
from exposure to sun and wind.
Hollow clay pots
Hollow clay pots where indicated for use in the composite floor slabs, are to be the sizes
shown on the drawings and to be of adequate strength to support the concrete during
placing and consolidation by vibration. They shall be obtained from an approved
manufacturer. Before any orders are placed, at least 6 sample clay blocks shall be
provided for the approval of the Engineer.
Hollow clay pots (cont’d)
Any clay blocks subsequently delivered to site which in he opinion of the Engineer are
not of equal standard to the approval samples shall be rejected.
Rejected pots shall immediately be removed from the site and shall not be used in the
works. Clay blocks are to be fully cured before delivery or use on site.
Defective or damaged pots are to be removed immediately from the site.
Generally
The hollow pot floor construction is generally to be as shown on the Engineer’s
drawings.
Care shall be taken in placing pots to ensure that they are set out in accordance with the
details shown on the Drawings and that they run truly in line without encroaching on the
width of the insitu concrete ribs.
The open ends of hollow pots, if adjacent to concrete to be placed insitu, are to be
plugged or stopped to prevent the concrete from flowing into the void and the contractor
is to include for this in his prices.
Before concreting is carried out the pots are to be thoroughly wetted.
Care should be taken during concreting that the width of ribs between the rows of pots
and the solid insitu concrete shown on the Drawings adjacent to stopping beams is not
encroached upon by the pots.
Where holes for services occur, the necessary holes or pockets shall be accommodated by
the replacing of a hollow pot by insitu concrete or the widening of a rib.
Prices for such holes through hollow pot slab construction are to include for the re-
arrangement or substitution of the hollow pot with solid concrete in addition to the actual
formation of the hole.
The concrete topping shall be poured at the same time as the ribs between hollow pots.
Reinforcement shall be positioned accurately with the specified cover in accordance with
the Drawings and using the particular spacer blocks as previously described
Spacer blocks shall be provided at not more than 1200mm centres.
Care must be taken during concreting that the reinforcement is not displaced.
WORKMANSHIP
A. PLANT AND METHOD
Before the commencement of any work, the Contractor shall submit the following for
the Engineer’s written approval:
(i) The concreting method, including the size and type of machines for
weighing and mixing concrete and the methods of transporting, placing and
compacting.
(ii) Details of formwork proposals, clearly indicating the general method of
construction and assembly, the method of achieving surface finishes
required herein, including lining, fixing of linings together with positions
of joints and the make and type of mould oil proposed.
(iii) The proposed position and type of every construction joint not already
shown of the Engineer’s drawings.
Such approval by the Engineer shall not be deemed to relieve the contractor of his
obligations to comply-with any of the provisions herein.
Concrete mixing and discharge from mixers shall be under permanent cover to the
Engineer’s approval.
B. MEASUREMENT AND MIXING
All cement is to be measured by weight, the 50kg. Bag of cement being used as a unit.
The amount of water shall be the minimum required to produce dense cohesive concrete
of adequate workability to be determined by trial mixes. This amount shall be accurately
gauged and adjusted from time to time to compensate for variations in moisture content to
the aggregates by an approved method
All concrete shall be mixed in a batch type mechanical mixer of approved type having a
drum rotating about a horizontal or inclined axis. The speed of the drum is to be not more
that twenty and not less than fourteen revolutions per minute.
Each mixer is to be fitted with a water measuring device capable of accurate measurement
to one gallon for one cubic yard mixers and prorata for smaller sizes and so arranged that
the accuracy is not affected by variations in the pressure of the water supply line. The
fine and coarse aggregate and the cement shall be mixed for at least four turns, after
which the required amount of water shall be added gradually while the mixer is in motion
and the concrete mixed for not less than one half minutes to a uniform colour and
consistency.
The volume of concrete mixed in any one batch is not to exceed the rated capacity of the
mixer.
The whole of the mixed batch is to be removed before materials for fresh batch enter the
drum.
Concrete as mixed in accordance with the foregoing shall not be modified by the addition
of further water or in any other manner on the cessation of work, including all stoppages
exceeding twenty minutes or any change of cement used in the mix, the mixer, and all
handling plant shall be washed out with clean water. At least one slump test shall be
made each day concreting is in progress under the supervision of the Engineer.
A. REINFORCEMENT
Reinforcement shall be free from all loose scale, loose rust, oil grease or similar defects,
immediately before placing the concrete. It shall be bent cold exactly to detail using
an approved bending machine. Hooks, bends, etc., where not specifically detailed, are to
be in accordance with B.S. 4461. Each bundle of bent bars shall be clearly tagged with
the bar list number.
Reinforcement shall be placed in the exact position shown on drawings with all inter-
sections tacked welded or securely tied with 16 gauge soft steel tying wire. The
designated cover shall be maintained by approved spacers, stools, bolsters or ties fixed to
the reinforcement. There shall be dense concrete left with a wire brushed surface or be
dipped in grout before fixing. These blocks are particularly important where the surface
of the concrete is exposed to weather or dampness. The Contractor must ensure that
bars are securely fixed so as to maintain their indicated positions during progress of
pouring, tamping or vibration of concrete. Six tools are to be provided around each
column to hold top steel in position and are to be made up of mild steel bars of
adequate diameter. The cost of providing and fixing these steel stools must be allowed
for by the Contractor in his rates for reinforcement generally. No laps or splices in bars
shall be made without prior approval of the Engineer except those detailed on the
drawings. The size and position of the reinforcement bars or mesh shall be approved by
the Engineer before concreting commences.
The insertion of reinforcement into concrete already placed, the lengthening of bars by
welding and the rebending of incorrectly bent bars will not be permitted.
For concrete having exposed surfaces, reinforcement shall be assembled and placed in
such a manner as to avoid any damage to formwork faces.
Where reinforced concrete slabs or walls are constructed against tanking, care shall be
taken in positioning reinforcement to avoid damage to tanking.
Unless otherwise shown upon the Engineer’s drawings, or specified in B.S. CP114, the
reinforcement bars shall be given the following cover of concrete:-
In floor slabs, walls and similar thin panelling, a cover of 13mm or the
size of the bar, whichever is the greater. In beams and other such
members, a cover of concrete of 25mm to the main reinforcement or the
size of the bar whichever is greater.
In columns a cover of concrete of 40mm to main reinforcement the size of
the bar, whichever is greater.
In foundations and column bases, a cover of 50mm to main reinforcement,
or the size of the bar, whichever is greater.
A. INSPECTION OF REINFROCEMENT
When the placing of reinforcement for a particular section of the works is completed and
before concreting commences, the reinforcement will be inspected by the Engineer and
no concrete shall be placed until the Engineer’s approval has been given. The Contractor
shall give the Engineer 48 hours notice of the time when the reinforcement will be ready
for inspection. Where the distance of the site of the Works is more than 100 kilometres
from the nearest office of the Engineer, this time shall be increased to 96 hours.
B. FORMWORK
Formwork shall be true to line, level face and profile and be of robust construction
adequately framed, braced, strutted, cramped, tied and propped to restrict deformation
due to construction loads to not more that 3mm, and to entirely eliminate deformation of
the form faces by warping or buckling. Wire ties will not be permitted. Formwork shall
be grout-tight under all conditions including vibration when specified or used.
Formwork shall be designed to allow prefabrication of conveniently sized elements to
facilitate ease of handling and assembly, to permit striking without force, shock or
any damage whatsoever to the concrete member or formwork face and permit the removal
of sides without disturbing soffits. Propping shall be carried down to an approved
bearing, shall not be supported by timber floors and shall be arranged that formwork
may be lowered smoothly.
Repropping will not be permitted. Provision shall be made for cleaning out and draining.
Formwork shall be constructed of material or lined with material as may be necessary to
achieve the finishes specified herein and in such a manner as to eliminate screw or nail
head imperfections.
Before each use, Formwork faces shall be treated with the minimum amount of an
approved mould oil necessary to obtain a clean release. Mould oil shall not come into
contact with the reinforcement.
The use of cement retarders will not be permitted except where a key for or other finishes
is required.
Before placing of the concrete, bolts and fixing shall be in position and cores and other
devices used for forming openings, holes, pockets, recesses, ducts or other cavities shall
be fixed to the shuttering.
Immediately prior to concreting, formwork shall be thoroughly cleaned out and
formwork and given his consent for concreting to proceed but such consent shall not
relieve the Contractor of his responsibility for its sufficiency. After striking, formwork
shall be cleaned, stacked and protected and before re-use, shall be serviced, made good
or replaced with new as may be necessary to maintain the finish and the standard
specified.
A. TOLERANCES
The maximum tolerances within which concrete work shall be constructed are as
follows:-
1. All setting out dimensions, and dimensions horizontally and
Vertically. + 5 mm
2. Section of concrete member + 15mm
3. Levels of floor slabs, beams, lintels etc. + 5 mm
4. Plumb of columns and walls in storey height + 5 mm
5. Plumb of columns and wall in full building height + 20 mm
6. Inside faces of life shafts in storey height + 5 mm
7. Inside faces of lift shafts in full building height + 15 mm
8. Concrete cover to reinforcement + 3 mm
No surfaces intended to be horizontal or vertical shall slope more than 2mm in l metre.
Any rectification of work not constructed within the tolerances set out above shall be
entirely at the responsibility and expense of the Contractor.
B. PLACING AND COMPACTION
No traffic whatsoever, wheeled or foot, shall take place over reinforcement placed
concrete and the Contractor shall provide all necessary stools, walkways, platforms and
barrow runs. Concrete shall be placed in its final position as rapidly as practicable by
methods which preclude segregation or loss of ingredients and in any case, within 30
minutes from the time that water is added to the mix; compaction shall be completed
before initial set commences. Partially set concrete shall not be re-worked or used.
Flowing in formwork shall be avoided by placing and compacting in shallow layers in
quick succession.
The workability of the concrete must never be altered by the use of additional water or
sand alone.
Foundations shall be placed their full depth in one operation and the top surface carefully
levelled. Concrete placed in timbered excavations shall be well rammed close against the
excavation face as the timber is withdrawn.
Where the design of the work demands the placing of reinforced concrete against the
sides of excavation without the use of formwork, the earth face in such locations shall
be prevented from crumbling or washing into concrete during placing and compaction
by any efficient means, and care shall be taken to maintain the correct cover to the
reinforcement.
All concreting shall be continuous to completion or to an approved construction joint.
Methods of placing and vibrating generally are to comply with the specifications for
vibrated concrete as laid down by the manufacturer of the vibrators used on the works.
During placing of all concrete a workman shall be in constant attendance with a hose pipe
to wash off any cement slurry which appears on the face of any previously poured
concrete immediately it occurs.
Concrete shall be placed into the forms from as less a height as possible and shall in no
case be dropped from a height of more than 1500mm except with the approval of the
Engineer.
When chuting is used, the inclination of the chute must be such as to allow the concrete to
flow without the use of excessive water and without segregation or loss of the ingredients.
Details of any proposed chuting plant must be approved by the Engineer before the plant
is delivered to the site.
If the Contractor wishes to distribute concrete by means of pumps, full details of the
system must be made available to the Engineer for approval.
Concrete shall be thoroughly compacted and carefully worked with suitable tools, into
formwork and around reinforcement and fixtures so as to avoid displacement. A
competent steel fixer shall attend throughout concreting to correct any unavoidable
displacement. Compaction shall be by means of vibrators; these shall be of an approved
pattern, of the immersion type; clamp on external vibrators, in adequate numbers shall be
used only where the density o reinforcement precludes immersion.
Attachments to reinforcement are expressly forbidden and accidental contact with
reinforcement shall be avoided. Vibration shall be executed by a competent operative
and shall not be carried out to the detriment of adjacent partly hardened concrete.
An accurate schedule is to be kept by the contractor showing dates and times when
various portions of the work were concreted. The concreting foreman must not vary the
approved mix or water content without the permission of the representative of the
Engineer. It may occasionally be found that in concreted members or where the
proportion of reinforcement in concrete is high, the workability of the concrete must be
increased especially in order to effect full compaction. Such increase in workability shall
be achieved by an increase in the mortar content of not more than 10% of the concrete
by weight in any single batch and must be made only with the approval of the
representative of the Engineer.
A. COLUMN PLINTHS
Column kicker plinths not cast monolithically with the beam or slab will be allowed only
at the discretion of the Engineer and special precautions must be taken if permission is
granted especially in regard to the quality of the mix used, and the curing of the concrete.
B. BLINDING CONCRETE
No casting of any concrete on the ground shall take place until the ground has been
passed as satisfactory by the Engineer. All ground to carry reinforced concrete shall be
covered with a blinding layer of a specified quality of concrete of the thickness shown on
the drawings or if not so shown a minimum of 50mm.
A. WATERPROOF CONCRETE
Whenever waterproof concrete is shown on the drawing it shall be mix 1:1 ½ : 3 nominal
and it shall be compacted by mechanical vibration so that a dense and homogenous mass
of concrete is obtained throughout every pour of the structure, all in accordance with
C.P. 2007.
The Contractor shall be allowed at his own cost to add an approved waterproofing
additive to the mix using it strictly in accordance with the maker’s printed instructions.
All permanent and construction joints shall be constructed in accordance with the
drawings and specifications to achieve complete water tightness.
It shall be the Contractor’s responsibility to ensure that all structures required to be
constructed in waterproof concrete are completely watertight and any work found to be
defective shall be made good to the Engineer’s satisfaction at the Contractor’s expense.
Where waterproof concrete forms a water retaining structure it is to be tested by filling with
water for a period of not less than four days. Any percolation or porous concrete or leaking
joint is to be made good at the Contractor’s expense. Tanks and pools constructed below
ground level are not to be backfield prior to the satisfactory completion of this test.
B. CONSTRUCTION JOINTS
All construction joints shall be straight, truly vertical or level, as the case may be, of
profile shown and formed in the exact positions shown on drawings or if not shown on
the drawings, with prior approval of the Engineer. Vertical joints shall be formed against
adequately secured rigid stop boards having splayed fillets, designed to pass the continuos
steel reinforcement without temporary bending or displacement.
The rate and method of placing concrete and the arrangement of joint bulkheads shall be
such that the concrete between construction joints shall be placed in a continous
operation.
Joints in reinforced slabs and beams, shall be perpendicular to the axis or surface of the
member jointed and at one third of the span. If an intersecting member occursat that
point, the joint shall be located at a point of minimum shear.
Construction joint in columns shall be as shown on the drawings. Wherever it becomes
necessary to stop work, such stops shall be located at one third span of slab and beams or
as directed by the Engineer.
An adequate and acceptable key of a succeeding work shall be formed by using stop
boards, which shall be constructed tightly to prevent any grout leak. As early as possible
boards shall be removed and the surface thoroughly hacked and brushed to remove all
laitence. Any leakage past stop boards shall be hacked off as soon as the concrete has
set. The surface shall be left clean and dry. Immediately prior to further concreting the
joint face shall be soaked with water and covered with sand cement mortar of proportions
identical to that in the concrete to be placed, punned into the body of the set concrete.
For exposed finishes, care shall be exercised to preserve an unbroken line at the exposed
edge of the joint.
In no circumstances shall the concrete be allowed to finish at a break running down a
rough slope. Such cases, if found, will be treated as contrary to the specification and
the Contractor will be required to cut out the member and re-cast. In the case of
horizontal joints, any excess water and laitance shall be removed from the surface after
the concrete is deposited and before it has set.
Before casting slabs the hauchings or seatings for the slab shall be thoroughly hacked,
scored and washed and covered with at least 5mm of mortar immediately before the
slab is cast.
Any necessary construction joints in foundations shall be stepped and lapped 600mm
joint faces shall be prepared and treated as described above.
A. STRIKING TIMES
It shall be the Contractor’s responsibility that no distortion, damage, overloading or undue
deflection is caused to the structure by the striking of formwork, but the Engineer
reserves the right to delay the time of striking in the interest of the work. Formwork
shall not be struck until the concrete has sufficiently hardened. Approval of the
Engineer shall not relieve the Contractor of his liability to make good any concrete
damaged by premature removal or collapse of forms. In no circumstances shall forms
be struck until concrete reaches a cube strength of at least twice the stress to
which the concrete may be subjected at the time of striking. The following striking times
given in days (24 hours) are the absolute minimum that will be permitted:-
Forms Ordinary Rapid
Portland Hardening
Cement Cement
Walls
Columns (Unloaded) 2 2
Beam sides
Slabs – props left under 7 2
Beam soffits – props
Left under 14 5
Slab – props 14 5
Beams – props 21 8
The time for removal of forms as cut shall not apply to slabs and beams spanning
more than 10 metres. For such spans appropriate times shall be recommended
or advised by the Engineer.
Where the structure is of multi storey construction props with head trees and
braces shall be provided to distribute the imposed load below the floor being
cast. This will be at least 2 storey heights below the floor being cast unless
otherwise stated.
A. CURING
The curing of the concrete must receive particular careful attention. The concrete shall
be covered with a layer of sacking, canvas, hessian or suitable absorbent material, and
concrete, formwork and covering kept constantly wet for the first seven days after casting.
B. MIXES, CHASES AND CASTING IN
No holes or chases are to be cut in reinforced concrete works. The contractor shall ensure
that all necessary holes and chases, including fixing holes for railings and balustrades etc.,
are carefully formed in the correct position by requisite measures prior to the placing of
concrete.
All conduits, pipes, tubes and the like shall unless otherwise detailed, be run on top of
the bottom reinforcement of the concrete work. It shall be the Contractor’s responsibility
to ensure full co-ordination with Sub-Contractors in the setting out for this purpose.
Generally, conduits, pipes and special fixtures shall be concreted in where required and
in the exact positions demanded.
Details of the positions of all holes, chases and fixing blocks shall be submitted to the
Engineer for his approval prior to putting the work in hand.
C. TESTS OF COMPLETE STRUCTURAL MEMBERS
The Engineer shall instruct that a loading test be made on the Works, or any part
thereof, if in his opinion such a test be deemed necessary for one or more of the
following reasons:-
(a) The site-made concrete tube cubes failing to attain the specified strength.
(b) The shuttering being prematurely removed.
(c) Overloading during construction of works, or part thereof.
(d) Concrete improperly cured.
(e) Any other circumstances attributable to negligence on the past of the
Contractor which, in the opinion of the Engineer, may result in the works,
or part thereof, being less than the required strength.
If the loading test be instructed to be made solely, or in part, for one or more of the
reasons mentioned above, the tests shall be made at the Contractor’s own cost. If a test
be instructed to be made for any other reason than specifically stated above, the
Contractor shall make the test and shall be reimbursed for all costs relating thereto.
Loading tests are to be conformity with Clause 605 of British Standard Code of Practice
CP 114.
If the result of the loading test be not satisfactory, the Engineer shall instruct thatthe part
of the works concerned shall be taken down or removed and reconstructed to comply with
this specification, or that such other remedial measures shall be taken as to make the work
secure.
If the tests be instructed to be made for one or more of the reasons (a) to (e) inclusive as
herein before specified, the Contractor shall take down or remove and reconstruct the
defective work, or shall take the remedial measures instructed all at his own cost.
A. PROTECTION
All insitu and precast concrete shall be protected from rain and during hot, dry and windy
weather approved hessian covering kept constantly damp shall be used to prevent
premature drying out.
All insitu and precast concrete shall be protected from damage by disturbance, shock
vibrations, early loading or overloading. In addition, all exposed finishes shall be
constantly protected from mechanical damage to arises or faces and damage due to
dropping, splashing and staining from any source including rusty scaffolding or
reinforcement.
No materials or equipment of any kind shall be stored or stacked on suspended floors
without the Engineer’s prior approval.
B. PRECAST CONCRETE
Precast concrete lintels shall comply with B.S. 1239.
Precast concrete kerbs shall comply with B.S. 340, figure 5
Concrete shall all be cast in properly made strong moulds to form shapes required.
For work described as “finished fair” the mould shall be lined with sheet or other
approved material to give the required surface finishes.
The coarse aggregate for precast concrete shall be 10mm gauge for mix specified.
The concrete shall be of the mixes described and shall be thoroughly tamped in the
moulds and shall not be removed from them until seven days after placing the
concrete, but the sides may be removed after three days providing the moulds are
such that the sides are easily removable without damaging the concrete.
The precast work shall be cast under sheds and shall remain under same for seven
days in the moulds and a further seven days after removal the moulds. During the
whole of this period the concrete shall e shielded by sacking or other approved
material kept wet. It shall then be removed from the sheds and stacked in the open
for at least seven days to season.
Precast concrete units shall be true and smooth on all faces (except where a key is
required for applied finishes). All arises shall be true and clean with no broken
edges.
All units shall be marked during manufacture to indicate
(a) The date of casting
(b) Identification lettering in accordance with the drawings
(c) Where necessary, the way up for building in.
Ends of bar reinforcement shall be 25mm from internal faces and 40mm from
external faces. Nominally non reinforced units may contain reinforcement at the
Contractor’s option for handling purposes, the cost of which shall be deemed to be
included in the pricing.
A. SURFACE FINISHES
After removal of shuttering, unless instructed to the contrary, the face of exposed
concrete is to be rubbed down immediately to remove fins or other irregularities. In
the event of parts of the concrete being honeycombed, such portions are to be cut to
depth and shape required b the Engineer and made up with fine concrete of equal
quality in such a manner as shall be directed. The face of concrete for which
shuttering is not provided, other than slabs, is to be smoothed with a wooded float to
give a finish equal to that of the rubbed-down surface where shuttering is provided.
The top face of slab which is not intended to cover with other material is to be
levelled and floated before setting to a smooth finish at the levels or falls shown on
the drawings or elsewhere.
The floating must be carried out in such a way as will prevent an excess of mortar
being brought to the surface of the concrete. The top face of a slab intended to be
surfaces with mortar, granolithic or similar material is to be brushed with a stiff
broom while still green to remove any laitance and provide a roughened surface.
(a) Samples Before the execution of any specified finish, the Contractor shall
prepare 1200mm square samples for the Architect’s approval.
No concreting in finish work shall be attempted until after the approval of a sample.
Approved samples shall be retained till the completion of all such work and closely
adhered to throughout the work. Rejected samples shall be demolished and removed.
(b) Rendered or plastered surfaces Concrete surfaces to be rendered or plastered
shall be thoroughly hacked to form a good key.
(c) Fair faced surfaces Fair faced surfaces shall be free from honeycombing,
stains, fins, lippings, nails holes or excessive air holes and shall be of a uniform
colour and texture. This surface shall be obtained by the use of.
(i) Wrot forms, i.e. timber forms planed smooth on the surfaces in contact with
concrete
(ii) Forms lined with hardwood or plywood or other approved material,
or
(iii) Smooth steel forms.
B. PRICING NOTES
The Contractor must allow for all costs incurred during the progress of the Contract for
complying with the provisions concerning the preparation of graded mixes.
Prices for concrete slabs shall include for all temporary formwork to form construction
joints at bay edges.
Prices for reinforced concrete shall include for filling into, between or on formwork and
thoroughly compacting between and around rods or fabric reinforcement and for forming
all additional construction joints between varying mixes.
Formwork is measured net to the actual face of the concrete to be supported and the
prices for formwork shall include for the extra material at joints, extra labour and waste
for narrow widths small quantities, overlaps, passings at angles, straight cutting and waste
splayed edges, notchings, etc., and for fixing at the various levels including battens,
struts, and supports and for bolting, wedging, easing, striking and removal Prices for
lineal items such as bocing shall include for angles and ends.
Prices for fabric reinforcement shall include for all straight cutting and waste, and
temporary support and all extra material in laps.
Prices of all precast concrete shall include for all moulds, finishing as described, hoisting
and fixing at the required levels, bedding, jointing and pointing in cement and sand
mortar, also for casting or cutting to the exact lengths required and any waste resulting
from such cutting. The sizes of weathered or moulded items stated are extreme sizes.
Prices for hollow block suspended slabs shall include for concrete filling run into the
open ends of blocks or blind end blocks.
Prices for expansion joints shall include for cutting to size and all temporary supports and
prices for expansion joint sealers shall include for all temporary battens or fillets
required to form the necessary grooves.
WALLING
MATERIALS
A. CEMENT
Cement used for making mortar shall be as described in “Concrete Work”.
B. LIME
The lime for making mortar shall comply with B.S. 890 Class A for non-hydraulic lime.
The lime to be run to putty in an approved lined pit or container.
The water to be first run into the pit or container and the lime to be added until it is
completely submerged, stirred vigorously until all lumps are disintegrated and shall be
kept constantly covered with water and regularly stirred for at least four weeks. The
resulting milk-lime then to be run through a fine sieve and run into a pit or other
container and kept clean and moist for not less than two weeks before being used in the
works.
C. SAND
Sand used for making mortar shall be clean well graded siliceous sand of good sharp hard
quality equal to samples which shall be deposited with and approved by the Architect. It
shall be free from lumps of stone, earth loam, dust, salt, organic matter and other
deleterious substance, passed through by the Architect sieve and washed with clean water
if directed by the Architect.
A. WATER
Shall be as described in “Concrete work.”
B. CONCRETE BLOCKS
Solid and hollow concrete blocks for walling shall comply with B.S. 2028 Type “A’ and
“B”, and the minimum compressive strengths given hereafter refer to table 2 of that B.S.
They are to be equal in every respect to a sample to be deposited with and approved by
the Architect. Walling is to be built in 200mm courses that is 190mm block h eight
plus a 10mm joint and of the thickness given herein.
They shall be hard, true to size, shape and with sharp arrises. For work below first floor
slab, blocks to be Type A7, All other blockwork to be Type B7.
They shall be obtained from an approved manufacturer or manufactured on site in
approved block-making machines. The mix used shall be not less than 1:9 by volume and
the maximum size of aggregate shall be 12mm size.
The blocks, on removal from the machine, shall be carefully laid on edge or racks under
sheds erected by the Contractor and left for 3 days during which period they hall be kept
constantly wet after which they shall be placed on edge in the open racks and protected by
sacking or other approved covering and kept wet for a further 5 days.
Thereafter, the blocks shall be left in the same position without wetting for a further 20
days.
No blocks will be allowed to be used in the works until 28 days old and until samples
have been tested and approved by the Engineer.
The Contractor is to ensure that blocks are stocked separately in their respective
categories and used in the structure in the positions shown on the drawings.
TABLE 2. COMPRESSIVE STRENGTH OF TYPE A AND B BLOCKS
Block
Type and
designation
Minimum compressive strength
Average of 10 blocks
Lowest individual block
A(3.5)
A(7)
A(10.5
A(14)
A(21)
A(28)
A(35)
N/mm2*
(MPa)*
3.5
7.0
10.5
14.0
21.0
28.0
35.0
Ibf/in2
500
1000
1500
2000
3000
4000
5000
N/mm2
(MPa)*
2.8
5.6
8.4
11.2
16.8
22.4
28.0
Ibf/in2
400
800
1200
1600
2400
3200
4000
B(2.8)
B(7)
2.8
7.0
400
1000
2.25
5.6
320
800
A. HOLLOW CLAY BLOCKS
Hollow clay blocks to comply with the provisions of B.S. 1190 section I, are to be hard
well burnt true to size shape and with sharp arrises and keyed faces and joints and
are to be obtained from an approved manufacturer and to be equal in every respect to a
sample to be deposited with and approved by the Architect. Blocks are to be 190mm
high (to give 200mm course height including the joint) and of the thicknesses given
herein. Cutting of blocks is to be avoided wherever possible and full use is to be made
of quarter, half and three quarter blocks, and blocks with conduit recesses.
B. STONE
Stone shall be sound and hard and free from all defects and shall be as approved by the
Architect.
All stone required for walling (unless otherwise described) shall be chisel dressed into
true rectangular blocks with each surface even and at right angles to all adjoining
surfaces. Ordinary walling shall be built 190mm courses, and of the thickness
given herein with all dimensions having a tolerance of plus or minus 6mm. At
least 80% of all stone blocks shall be not less than 500mm in length and no block will
be allowed to be cut or redressed after it is built into the work.
C. CLAY GRILLERS
To be from an approved manufacturer, hard, well burnt, true to shape and size and equal
in all respects to samples to be deposited with and approved by the Architect. Grilles to
be built in regular courses with vertical joints straight and true.
D. FACING BRICKS AND TILES
Clay facing bricks and tiles, shall be obtained from an approved manufacturer and shall
match in all respects a sample deposited with and approved by the Architect.
E. CORAL
(i) Coral shall be sound and hard and may be selected from materials arising
from the excavations if approved by the Architect.
(ii) Coursed Coral for walling (unless otherwise described) shall be chisel
dressed into true rectangular blocks with each surface even and at right
angles to all adjoining surfaces. Ordinary walling shall be built in 190mm
courses, and of nominal 100mm, 140mm, 150mm, 190mm, 230mm
thickness with all dimensions having a tolerance of plus or minus 6mm. At
least 80% of al coral blocks shall be not less than 510mm in length and no
block will be allowed to be cut or redressed after it is built into the work.
(iii) Where described as coral rag the stones shall be irregularly shaped and
selected for soundness, colour and texture and roughly hammer dressed if
required. The finished face is to be left absolutely free from mortar and
other smears and blemishes.
A. WALL REINFORCEMENT
Walls less than 200mm shall be reinforced with a 25mm wide strip of 16 gauge thick
hoop iron built into alternate horizontal joints in the wall centre. The reinforcement shall
be lapped and hooked at running joints, angles and intersections and carried at least
115mm into abutting walls at junctions.
B. WALL TIES
To be 3mm diameter galvanised mild steel wire twisted butterfly wall ties.
C. DAMP PROOF COURSE
To be asbestos base fully bitumen impregnated in accordance with B.S. 743 weighing not
less than 3.80 kgs. Per square metre. The sheeting is to be lapped 150mm at running
joints and the full width of walls at angles.
WORKMANSHIP
D. CEMENT MORTAR
Mortar described as cement mortar 1:5 shall be composed of 1 cubic metre
(1442kgs.) of Portland cement to 5 cubic metres of sand. Other mixes such as 1:3, 1:4,
shall be similarly construed.
E. CEMENT LIME MORTAR
Mortar described as cement lime mortar 1:1:4 shall be composed of 1 cubic metre (1442
kgs.) of cement and 1 cubic metres of lime and 4 cubic metres of sand. Other mixes shall
be similarly construed.
F. MIXING OF MORTARS
The constituent materials shall be measured separately when dry in specially prepared
gauge boxes of sizes to give the proportions specified without consolidation of
the contents by ramming and shaking. The mortar shall be mixed in an approved power
driven mixer for not less than two minutes per batch and using the minimum
quantity of water necessary to obtain a working constituency. The mixer shall be
used as close as practicable to the works and mortar shall be used within 30 minutes
of mixing. No partially or wholly set mortar will be allowed to be used or re-mixed.
G. GENERAL CONSTRUCTION
(a) Setting Out. The Contractor shall provide proper setting out rods and set out
all work on same for courses, openings, heights, etc., and shall build the wall,
piers, etc., to the widths, depths and heights indicated on the Drawings and as
directed by the Architect.
(b) Building in Wood Frames. Openings for doors ventilator, etc., are to be set
out and left unbuilt until the wooded frames have been fixed in position.
(c) Building in Metal Windows and Doors openings. For metal frames are to be
wide enough for the frames to fit without being forced into position. Build the
lugs into the joints of the walling and fill in the space between the walling and
frame with cement mortar 1:5 well tamped into the channel of the frames
and point all round externally.
All frames must be set plumb and level and free from twists.
(d) Walls to receive Plaster and similar finishes. All faces of walls to be
plastered, etc., to have all projections dressed off and joints raked out as
key.
A. BUILDING WALLING
(a) Laying and jointing. All blocks shall be well wetted before being laid and
the top of walling where left off shall be well wetted before recommencing
building. Walls throughout the Works shall be carried up evenly in
200mm courses except where courses of less depth are required to bring
walling up to level of floors, windows and the like and where otherwise
described, no part being allowed to be carried up more than one metre
higher at one time than any other part and in such cases the joining shall be
made in long steps so as to prevent cracks arising and all walls shall be
levelled round at each stage.
Blocks shall be bedded and jointed in cement mortar (1:5) as described
with beds and joints 10mm thick, all flushed up and grouted solid as
the work proceeds.
All walling shall be properly protected and kept wet for three days after
Building.
(b) Bonding The blocks shall be properly bonded together and in such
manner that no vertical joint in any one course shall be within 115mm of a
similar joint in the courses immediately above or below. All walling of
300mm thickness or less shall be built in single thickness of blocks.
Walling exceeding 300mm in thickness shall be built with through bonders
not more than 1070mm apart in each course as directed by the Architect.
Alternate courses of walling at all angles and intersection shall be carried through the
full thickness of the adjoining wall. All perpends, reveals and other angles of the
walling shall be built strictly true and square.
Alternate courses in attached piers, etc., to be of single blocks and the vertical joints in
alternate courses to midway between back and front faces.
B. FAIR FACE
All concrete and hollow clay blockwork described as finish with a fair face is to be built
to a true and even face with the joints finished as specified hereinafter.
C. BRICK AND TILE FACING
(a) All brick and tile facework shall be set out and built to the respective
dimensions, thickness and heights shown on the drawings. The bricks or
tiles shall be well laid with 6mm joints and pointed with neat weathered
joints as the work proceeds.
(b) A sample panel about 1 metre square of each of the facings is to be
constructed on the site and when approved by the Architect shall be
retained as the Standard for the Works and cleared away on completion all
at the expense o the contractor.
A. HOLES CUTTING AND CHASING
(a) All putlog holes shall be not less than one course deep and carefully filled with
a block cut to fit size of opening with beds and joints filled in with mortar well
tamped in after scaffolding is removed, and if in faced walls, to match
facings.
(b) Where walling is cut, holed or chased for conduits’ pipes and the like all such
cuttings, etc., shall be filled in with cement mortar (1:4) prior to the application of
finishes.
B. CORAL RAG FACING
Coral rag facing shall consist of irregularly shaped stones rough hammer dressed to a
50mm thickness and bedded against concrete block walling and pointed in cement and
sand (1:5) mortar. The finished face is to be free from mortar stains and wire
brushed.
C. LOUVRE BLOCK WALLING
(i) To be precast concrete Grade “20” with 10mm aggregate finished fair on
all exposed surfaces and built in cement mortar (1:5) with straight
horizontal and vertical joints and flush pointed both sides.
(ii) Each block size 200mm x 400mm long x 200mm high and consisting of
two ends each 200mm x 200mm x 50mm thick joined with 50mm thick
twice cranked louvre with top end of louvre projecting 40mm above top of
block.
D. PRICING NOTES
Price for all walling shall include for normal rough and straight cutting, plumbing angles,
all cutting and waste and split courses necessary for bond, bonding at angles intersections
and junctions of all thicknesses, split courses, cutting and pinning up to columns beams
slabs, etc., cutting and pinning in ends of cills, lintels, beams etc. Forming all openings
and reveals to same and all cutting and waste to walling in short lengths such as mullions
unless specifically measured.
Prices for all walling shall include for hoisting and building off beams and slabs at any
level and work built over-hand.
Prices for hollow block walling must further include for all necessary solid blocks or fine
concrete filing to open ends of blocks at intersections, ends and angles of walling.
ASPHALT WORK
E. Generally
All asphalt is to be manufactured and applied strictly in accordance with the appropriate
B.S. or C.P. as stated hereafter.
F. COLD APPLIED ASPHALT (COLAS)
Shall be as manufactured by Ms. Colas East Africa Ltd of P. O. Box 46644 Nairobi, or other
equal and approved manufacturer and applied in accordance with manufacturer’s written
instructions.
BASE TANKING AND DAMP-PROOF COURSES
A. Materials and Workmanship
Mastic asphalt to comply with B.S. 1162, subsection 1418 (natural rock asphalt
aggregate) or B.S. 1415 (limestone aggregate) and to be laid in accordance with C.P.
110 “Protection of Buildings against Water from the Ground”
B. Basement damp-proof course
Lay over the whole area of the basement floor on concrete bed horizontal damp-proof
course in three thickness laid with 150mm laps to a total thickness of 30mm and carried
through walls to connect with vertical damp proof course with a two-coat angle fillet.
C. Vertical damp-proof course to basement
Cover outer face of basement walls with a vertical damp-proof course applied in three
thicknesses with 75mm laps to a total thickness of not less than 20mm. To be carried up
to a minimum height of 150mm above ground level and connected to horizontal damp
proof course in walls to form a complete tank to basement.
D. Column reinforcement
Ensure that a good, tight joint is made to column reinforcement where projecting through
basement slab and that thickness of asphalt is maintained at these junctions.
E. Basement asphalt protection
Immediately following the laying of the basement asphalt provide and lay over the whole
of the basement area a fine concrete screed as specified to minimum thickness of 50mm.
F. Water level
Maintain the water level at not less than 300mm below the level of the basement slab
concrete during the progress of the tanking work to avoid application of asphalt to wet
surfaces. Pumping operations are to continue until the temporary sump has been filled
and sealed.
G. Back filling
When back filling to basement ensure that the nature of the fill is such that the vertical
damp proof course will not be damaged or punctured and that the pressure exerted
against the vertical damp proof course will not cause the asphalt to squeeze out.
H. Horizontal damp-proof course
Lay over the whole thickness of the external walls at a minimum height of 150mm above
ground level 20mm thick horizontal damp-proof course in two thicknesses with 75mm
laps.
Lay over the whole of thickness of all internal walls and partitions 13mm horizontal
damp-proof course with 75mm laps.
A. Vertical damp-proof course
Where required because of differences in ground and floor levels, lay on all external walls
a 13mm minimum thickness vertical damp proof course in two coats and connection to
horizontal damp proof courses by angle fillets.
B. Parapet Walls
(a) Continous with asphalt skirtings lay through the full thickness of all
parapet walls a 13mm horizontal damp-proof course
(b) Lay immediately under copings through full thickness of parapet walls a
13mm horizontal damp proof course.
ROOFING IN ASPHALT
C. Felt underlay
To be black sheathing felt to comply with B.S. 747, Class 4A (i0 (bitumen based
impregnated flax felts)
D. Asphalt
To be mastic asphalt for roofing to comply with B.S. 1162 subsection 1418 (natural rock
aggregate with bitumen) or B.S. 988 (limestone aggregate).
E. Workmanship
The asphalt is to be laid in accordance with C.P. 144. Part 2 (Mastic asphalt).
F. Roof covering generally
(a) (On concrete)
lay over the whole of the roof surfaces. On roof plan asphalt of 20mm
minimum thickness in two coats with 75mm laps on and including an
underlay of sheathing felt and laid to falls provided in the screed.
(b) (On timber)
Lay over the whole of the roof surfaces on roof plan asphalt of 20mm
minimum thickness in two coats with 150mm laps on and including an
underlay of sheathing felt and laid to falls provided by firring.
G. Skirting or upstands
(a) Form a two-coat skirting or upstand at junctions of flat roof with parapet walls,
stacks and other abutments to a minimum height of 150mm above highest part
of roof covering with angle fillet joint to roof covering and splayed at top and
turned in at least 20mm into groove in wall and jointed in cement and sand
1:3 (or connected to damp-proof course in parapet walls).
(b) (On timber)
Generally as on concrete.
Also carry asphalt over free-standing timber splayed fillet at junction with parapet
wall on and including heating felt and expanding metal latching. Dress the flashing
set in the wall down over the skirting.
Form all necessary angles and splays, etc., as the work proceeds.
A. Verges
Cover the verges with asphalt in two coats with rounded angles and angle fillet at junction
with roof covering to a minimum thickness of 20mm and to a minimum depth of
150mm. Include raised water check set in not more than 20mm from edge of roof.
B. Eaves
Finish the edge of asphalt against all eaves gutters with fair rounded edge dressed on
to welted metal flashing.
C. Parapet and Valley gutters
Line the parapet or valley gutters with asphalt 20mm thick in two layers on and including
sheathing felt (and expanded metal if of boarded construction) with angle fillets at
bottom and rounded edge to roof covering. Form skirting to parapet wall.
D. Rainwater outlets
(a) (Internal)
Properly dress asphalt to rainwater outlets, finishing with rounded edge, and dress
into luting flange.
(b) (External)
Carry asphalt through outlets in parapet walls with skirting to both sides
properly dress over welted metal flashing and finish with rounded edge.
PAVING AND FLOORING
E. Asphalt
Mastic asphalt to comply with B.S. 1162, subsection 1410 (natural reck asphalt
aggregate) or B.S. 988 subsection 1076 (limestone aggregate) and/or subsection
1451 (limestone aggregate – coloured finish).
F. Workmanship
The asphalt is to be laid in accordance with C.P. 204, Part 4 “Insitu flooring.
G. Paving and Flooring
Pave the areas on to specified thickness in one layer. Form skirtings against walls to a
height of (100mm) and 20mm thick and turn into chase in walling (or finish with
rounded top edge). Include angle fillets at internal angles of skirtings and between
skirting and paving and rounded external angles.
Lay external pavings to falls provided in the concrete towards channels and/or
outlets and the line channels with asphalt 20mm thick.
ROOFING
A. GENERALLY
All roof materials shall be as specified in the Bills of Quantities and laid in accordance
with the manufacturer’s instructions.
GALVANISED MILD STEEL ROOFING
B. Sheeting
Sheeting shall be hot-dip galvanised best quality mild steel sheeting to specified
gauge to comply with B.S. 3083.
C. Laps
Sheeting shall be laid with end laps to comply with C.P. 143201 and side laps of 1½
corrugation on the side away from prevailing winds.
D. Fixing to Timber
The sheets shall be fixed to timber with 6mm diameter galvanised mild steel roof screws
65mm long, each with one plastic “Selawasher” or a Bituminous washer with one
galvanised steel diamond shaped washer.
E. Holes
Holes for bolts or screws shall be punched from the inside of the sheet and through the
ridges of corrugations not the valleys.
F. Ridges and valleys etc
The ridges and valleys etc., shall be formed of galvanised mild steel sheeting of a quality
equal to that of the roofing sheets. Ridges shall be seam bolted to the sheeting on each
side at 450mm centres maximum with 12mm diameter seam bolts 20mm long each with
one plastic washer or a bituminous diamond shaped washer with galvanised
diamond shaped steel washer and one galvanised steel nut. Ridges and valleys shall be
not less than 380mm girth.
G. Bolts and Screws
All fixing bolts and screws shall comply with B.S. 1494.
H. Square Abutments
At square abutments the last two corrugations of the corrugated iron sheets next to
walls shall be flattened and turned up against wall and covered with 18 gauge
galvanised sheet iron apron flashing.
ASBESTOS SHEET ROOFING
A. Sheeting
Asbestos cement roof sheeting and accessories shall be of “Superseven” or other specified
type to comply with B.S. 690 and of an approved colour as stated, shall be simbarits
Brand Manufactured by Kenya Asbestos Cement Co. Ltd., Mombasa unless
otherwise specified. The thickness of the sheeting shall be not less than 6mm or as
specified and shall be laid and fixed strictly in accordance with the manufacturer’s printed
instructions.
The pitches of 15 degrees and under and in exposed position sheets are to be fixed to
every purlin and at every fourth corrugation. At bottom edges the sheeting shall be
fixed every alternate corrugation.
B. Laps
Sheets shall be laid with the end laps to comply with C.P. 143201 and side laps of 1½
corrugation on the side away from the prevailing winds.
C. Fixing
The sheets shall be fixed to timber purlins with 7mm galvanised gimlet pointed
screws 115mm long and to steel angle purlins or “Z” section steel purlins with 7mm
diameter galvanised hook bolts and nuts. All screw and bolt fixing shall have
“selawasher” plastic washers.
D. Holes
Holes for bolts shall be drilled through the ridges of the corrugation not the valleys.
E. Bolts and screws
All fixing Bolts and screws and other accessories shall comply with B.S. 1494.
F. Intersections
Where four sheets meet, two sheets shall be cut and mitred for the full length of the end
lap and the full width or the side lap at the appropriate corners to ensure three
thicknesses of sheeting at this point.
G. Ridges, etc.
Ridges and other accessories shall be supplied as shown on the drawing and shall be
fixed to timber and steel purlins as above described.
H. Fixing to Wall Plates
Where sheeting is fixed to wall plates it is to be executed as described above but in
addition special eaves closer pieces are to be provided if beam filling is not required.
APPLIED ROOFING GENERALLY
A. Protection
The Contractor will take all necessary precautions to ensure that no damage is
caused to the roofing after completion of laying, by further building operations,
storage of heavy objects, traffic or any cause whatsoever.
B. Examination on Completion
Before delivering up the works, the Contractor shall examine the roof coverings, clear
away all rubbish, clean out gutters and rain water pipes and leave a sound watertight
finish.
C. Aluminium - alloy sheeting
To be (24, 22) s.w.g. (0.56, 0.71) aluminium-manganese alloy NS3 sheeting, either:
(a) Corrugated or mansard profile to comply with B.S. 2855, or
(b) Troughed profile to comply with B.S. 3428 (type A or B)
Fittings are to be (22, 20) s.w.g. (0.71, 0.91mm) and are to include roll-top or
angular socketted one end ridge members, hip cappings, eaves fillers, plain and
corrugated side-wall flashings, etc.
D. Translucent corrugated plastic sheeting
To be ‘Unilux” or other approved glass fibre reinforced translucent corrugated
plastic sheeting to comply with B.S. 476. The sizes and corrugations of sheets are to
suit main roof sheeting.
E. Fixing sheeting and fittings
Fixing to be by means of 6mm or 8mm diameter galvanised mild steel hook bolts (to steel
purlins) and/or drive screws ( to wood purlins) together with nuts and soft plastic
washers with dome-shaped caps all to comply with B.S. 1494.
The hook bolts and/or drive screws are to be spaced two per sheet per purlin and
holes are to be drilled in the crown of the corrugations for this purpose.
End laps of sheetings to be 150mm and side laps to be 1 1/2 corrugation or otherwise as
instructed by the manufacturer.
Fittings are to be fixed in the same manner as the general sheeting if the joint lies on a
purlin. If the joint does not lie on a purlin seam bolts of the same diameter as the
hook bolts and/or drive screws are to be used together with nuts and plastic washers as
before described. To be spaced two per sheet.
F. Valley gutters
To be (375mm, 450mm, 525mm or larger) heavy, pressed steel valley gutters to
comply with B.S. 1091 (Alternatively, for corrugated asbestos-cement sheet roofs,
asbestos cement valley gutters to B.S. 569 may be specified).
Joints to be bedded in mastic and bolted with countersunk headed galvanised mild steel
screw bolts, with bolt heads set inside gutter. To be fixed by means of heavy
galvanised pressed steel brackets bolted to the lowest purlins and spaced one per
1M. length of gutter.
A. Roof surfaces generally
Provide and lay over the whole areas shown on roof plan, roof sheeting to purlins as
specified.
B. Ridge
Provide and fix ridge capping complete with gable finials all as specified and as the
work proceeds.
C. Eaves
(a) Allow sheets to project at least 600mm at eaves and joint to beam filling in
cement mortar (1:3) to fill underside of corrugations for the entire thickness
of the beam filling.
(b) Provide and fix eaves fillers fixed to both roof sheeting and wall cladding to
provide eaves enclosure as the work proceeds
D. Verges
(a) Allow roof sheeting to overlap gable walls 75mm minimum and bed point
sheeting to wall in cement mortar (1:3) as the work proceeds.
(b) (To similar sheet gable cladding). Provide verge trims as specified and fix
to roof sheeting only to overlap gable cladding. Make good to gable finial
and ridge capping and at eaves.
E. Valleys
Provide and fix valley gutter as specified between adjacent roof slopes and to falls to
discharge into rainwater heads.
F. Roof lights
In the positions indicated on the roof plan, provide and fix single sheeting as
specified in place of the general roof sheeting to form roof lights.
G. Clay tiles
Shall be as manufactured by Clayworks Ltd., P.O Box 45154, Nairobi or other equal and
approved manufacturer, and shall be true to dimensions as specified.
H. Interlocking concrete tiles
Shall be concrete interlocking tiles as manufactured by Mareba Enterprises Ltd., P.O.
Box 40619, Nairobi or other equal and approved.
The bottom course shall be laid first. Adjustments of the head lap shall be made on at
least first three courses if the rafter length does not accommodate an exact number of
full tiles.
Tiles shall be laid to a minimum head lap of 76mm side lap of 35mm. The maximum
batten gauge shall be 343mm.
Shingles
A. Battens
To be pressure impregnated, 50 x 25mm sawn softwood battens set to 125mm
gauge.
B. Shingles
To be first grade, pressure impregnated, or oil dipped edge grain (i.e. cut from the
block at right angles to the annular rings), sawn cedar shingles average size 500 x
200mm and tapering from 3mm thick at the head to 10mm thick at the tail.
C Laying Shingles
To be laid breaking joint and nailed through two thicknesses of shingles to each
batten. To have double course (full length) at eaves and one-and-a-half width
shingles in each alternate course at verges to break joint. Ridges and hips to be
capped with shingles as main roof.
D. Roofing surfaces generally
Form ridges hips and finish edges at eaves and verges, all as specified, and cut and fit
shingles at abutments and valleys to receive metal flashings.
Bituminous Felt Roofing
E. Generally
All bituminous felt as to be manufactured and applied strictly in accordance with
appropriate B.S. or C.P. as stated hereafter.
F. Bituminous Roofing Felt
To be built-up bituminous felt roofing in three layers of self finished bitumen felt
weighing 13.6kg/10m2 to comply with B.S. 747, Class 1C (i.e. fibre based).
G. Insulation and vapour barrier
To be 13mm thick approved fiberboard insulation laid with butt joints to a vapour
barrier consisting of one layer of coated bitumen roofing felt weighing not less that
13.6kg/m2 laid over the whole surface.
H. Surface finish (non-pedestrian traffic)
To be grey stone (or white marble) chippings, average size 12mm laid over the
surface in hot bitumen dressing compound. Chippings to be omitted in gutters and
stopped short of edges and 300mm clear of rainwater outlets and the bottom of angle
fillets.
Roofs steeper than 10 degrees are not to have chippings.
The areas not covered with chippings shall be finished with a layer of mineral
surfaced, bitumen felt weighing 36kg/m2 instead of the top layer of roofing.
A. Surface finish (pedestrian traffic)
To be fine bitumen macadam lightly rolled to 13mm thickness and sprinkled with
3mm limestone grit rolled in.
B. Roofing generally
To be laid in three layers as specified with 50mm side laps and 75mm end laps,
staggered, the layers bonded together with hot bitumen bending compound as
described in C.P. 144.
C. Abutments
Felt to be carried up abutment over fillet (concrete or wood) and each layer tapered to a
height of 150mm above roof surface as skirting to be covered by metal flashing.
D. Verges
Felt to be carried over roll (concrete or wood) and over verge to a depth of 150mm and
bonded to edges of verge with hot bitumen bonding compound.
E. Parapet gutters
Felt to be carried into gutter and up parapet wall as abutment. Felt to be laid to lap
with, and not against, the fall in the gutter.
F. Eaves gutter
Felt to be laid over edge of roof and dressed into gutter with edge welted.
G. Rainwater outlets
Felt to be carried through outlets in parapet walls with skirtings to both sides of
outlets and dressed over edge of parapet wall and into rainwater head.
H. Roof surfaces generally
Provide and fix insulation and vapour barrier, lay surface dressing and form junction and
joints at abutments, verges, eaves and parapet gutters and rainwater outlets, all as
previously specified.
I. SAMPLES
The Contractor shall as and when required by the Architect, submit and deliver
samples of any materials for testing.
J. STATEMENT AS TO SCREED AND UNDERBED
The Contractor is to obtain from Sub-Contractor a statement in writing to the effect that
the screed and/or underbed is laid to the correct falls and is clean and otherwise
satisfactory before the covering of felt is laid. A copy of the statement is to be
forwarded to the Architect.
A. GUARANTEE
The Contractor is to obtain from the specialist firm a written guarantee and
undertaking to the effect that during a period of two years from and after the
certified date of completion of the works, such sub-Contractor shall at his own
expense make good to the satisfaction of the Architect, all and any defects in the felt
roofing work which shall be attributable to improper materials or faulty
workmanship and shall bear the cost of any consequential damage as is provided for
in such guarantee.
MATERIALS
B. PRIMER AND BONDING COMPOUND
Primer and bonding compound shall be oxidised or ‘blown’ bitumen melted and
applied hot.
WORKMANSHIP
C. PREPARATION
All surfaces to receive felt are to be cleaned before and as work proceed. Felt shall not
be laid until sufficient time has been allowed for the screed and underbed to
become completely dry and free from water vapour. Felt shall not be laid whilst the
screed or underbed is wet.
D. FALLS
All work shall be laid to falls without hollows or loose patches.
E. PRIMING
Primer shall be applied overall to vertical surfaces, kerbs and skirtings.
F. LAPS, BONDING, ETC.
All roofing shall be laid with number of layers of felt described to a maximum
thickness of 10mm lapped across falls with minimum laps of 50mm at edges and
75mm at ends of sheets, fully hot bonded either by pouring and rolling or mopping
with bitumen bonding compound laid to an even thickness using 13kg bitumen per
square metre of roofing between layers, with successive layers of felt laid breaking
joint.
G. STAINS, ETC.
All adjoining work shall be protected from damage during laying and all stains shall be
removed and made good.
CARPENTRY AND JOINERY
MATERIALS
A. QUALITIES AND GRADES OF TIMBER
(i) All timber used for permanent work in the building shall conform in all
respects to K.S. 02-17.
(ii) The qualities and grades of timber stated hereinafter conform to Table 1 of
Section 4 of K.S. 02-17 which is reproduced hereunder.
GRADE APPLICATION
F Furniture and high class joinery
S75 Structural grade having grade stress
value of 75% of basic stress
S50 Structural grade having grade stress
value of 50% of basic stress
C General construction grade for non-
stressed construction
GJ General Joinery
(iii) All timber for permanent work in the building shall before use be approved
by th eArchitect for quality in accordance with the foregoing specification
for its respective grade. Any timber not so approved by the Architect shall
be removed from the Site forthwith.
B. INSECT DAMAGE
All timbers whether graded or ungraded, and including shuttering scaffolding and the
like shall be free of live borer, beetle or other insect attack when brought upon the
site.
The Contractor shall be responsible up to the end of the maintenance period for
executing at his own cost all work necessary to eradicate insect attack of timber
which becomes evident including the replacement of timbers attacked or suspected
of being attacked, notwithstanding that the timber concerned may have been
inspected and passed as fit for use.
C. SEASONING OF TIMBER
All carpentry timbers are to be seasoned to an average moisture content of not more than
20%. The Contractor is to make available on site a meter for testing moisture
content of all timber delivered.
A. PREPARATION AND PROTECTION OF TIMBER
(i) All timber necessary for the works is to be purchased immediately and
when delivered, is to be openstacked for such further seasoning as may be
necessary. Preparation of timber is to be commenced as early as possible.
(ii) All timber and assembled woodwork is to be protected from the weather
and stored in such a way as to prevent attack by decay, fungi, termites or
other insects.
B. SPECIES OF TIMBER
Only those timbers specified in these Bills of Quantities are to be used for the
Works, unless alternatives are authorised by the Architect in writing.
C. PRESSURE IMPREGNATED TIMBER
(i) All timber described as pressure impregnated shall be impregnated under
vacuum and pressure with the “Celcure” wood preservative with an average
absorption of not less that 6.7kgs. of dry Celcure salt per cubic metre. In
case of resistant species where this retention cannot be obtained the timber
shall be treated to refusal point. All treated timber shall be exposed to wet
conditions for at least 14 days after treatment has been carried out. All cut
ends, drilling or fabrications on the Site producing new surface shall be
thoroughly brushed or soaked with “Celcure” salts applied in accordance
with the manufacturer’s instructions.
(ii) Any other method of timber impregnation will only be allowed at the
Architect’s approval.
D. TIMBER BUILT INTO MASONRY
Ends of timber built into walls shall be thoroughly brush treated with creosote or
other approved preservative and clear space maintained around timbers where they
adjoin the walls.
E. DIMENSIONS
Before putting in hand any joinery work, whether built-in or fixed later, the joiner is to
ascertain and check on site all dimensions, which affect or govern the joinery
work.
F. BLOCKBOARD
Blockboard shall be of approved local or imported manufacture, to B.S. 3444, glued
throughout and softwood or hardwood faced as hereinafter specified and equal to a
sample to be deposited with the Architect for approval and which when so approved
shall form the standard for the works.
G. PLYWOOD
Plywood to be of approved manufacture according in all respects with B.S. 1455;
interior type to be Grade I and exterior type Grade II weather-resistant (not less than
B.R. Bonding).
A. FIBREBOARD
Shall be insulating board to comply with B.S. 1142 of the types specified and of
approved manufacture.
B. TEMPERED HARDWOOD
To be of approved manufacture in accordance with B.S. 1142, suitable for painting,
prepared and fixed in accordance with the maker’s instruction.
C. ASBESTOS SHEETING
To be “Simbarite” flat sheets of 4mm or 6mm as described hereafter.
D. LAMINATED PLASTIC
To be 1.6mm Formica or other equal and approved laminated plastic sheet to B.S.
3794 in colours to be selected by the Architect and bonded on with the
manufacturer’s recommended adhesive all in accordance with their printed
instructions.
E. WOOD PARAQUET FLOORS
(i) To be to specified thickness and not less than 8mm parquet tiles supplied
and laid by a Specialist all to the approval of the Architect. The screed is
to be primed and when cured the tiles are to be bedded thereon in adhesive;
both the primer and adhesive are to be recommended and approved by the
tile supplier.
(ii) Upon completion and immediately prior to applying the sealer, the surface
is to be twice machine sanded using first coarse and then fine sand paper
and brushed perfectly clean.
F. MAKUTI
To be first quality and obtained from a source approved by the Architect and each piece
to be fixed to roof timbers securely tying on with sisal string.
G. FLUSH DOOR
Shall comply in all respects other than the following modifications with
B.S. 459 part 2:-
(a) To be 45mm thick and of the size stated in the Bills of Quantities.
(b) Core shall be seasoned softwood grade GJ.
(c) Hardwood lipping to be Graded thick tongued on back face into styles and rails
of core mitred at angles and glued in.
(d) Semi-Solid Core to consist of 75mm wide style, top and bottom rails all
framed together with two 500mm x 150mm look blocks framed in and
20mm intermediate horizontal rails at 50mm centres stub tenoned in each
end to styles. Each horizontal rail and top and bottom lipping to have
12mm diameter hole bored through to ensure air circulation through core.
Plywood facing to be 4mm thick.
(e) Solid Core (and half-hour type fire check doors) to consist of 75mm styles top
and bottom rails with solid core of 12mm horizontal strips glued together
under pressure. The strips to be put together with the grain alternating and to be
tongued on edge and let into vertical grooves in styles. Plywood facing to be
6mm thick.
(f) A sample must be approved by the Architect before an order is placed and all
doors must be equal to the standard of the approved sample.
A. NAILS, SPIKES AND BOLTS
Nails, spikes and bolts shall be the best quality mild steel and of lengths and weights
approved by the Architect. Nails shall comply with B.S. 1202, wood screws with
B.S. 1210, and bolts with B.S. 916.
WORKMANSHIP
B. JOINTING
(i) All joints must be made as specified or detailed and the execution of all
jointing shall be to the satisfaction of the Architect.
(ii) Jointing surfaces of all connections exposed to the weather are to be thickly
primed except where glueing is specified. Surfaces are to be in good
contact over the whole area of the joint before fastings are applied.
(iii) No nails, screws or bolts are to bolts are to be placed in any end split. If
splitting is likely or is encountered in the course of the work, holes for nails
are to be pre-bored at diameters not exceeding 4/5ths of the diameter of the
nails. Clenched nails must be bent at right angles to the grain. Lead holes
are to be bored for all screws.
(iv) Where the use of bolts and washers is specified the holes are to be bored
from both sides of the timber and to be a diameter D + D/16 where D is the
diameter of the bolts. Nuts must be brought up tight but care is to be taken
to avoid crushing of the timber under the washers.
(v) Joints in joinery must be as specified or detailed and so designed and
secured so to resist or compensate for any stresses to which they may be
subjected. All nails, springs, etc., are to be punched and puttied.
(vi) Loose joints are to be made where provision must be made for shrinkage,
glued joints where shrinking need not be considered and where sealed
joints are required. All glued joints shall be crosstongued or otherwise
reinforced.
(vii) Glues for load-bearing joints or where conditions may be damp must be of
the resin type. For non-load-bearing joints, or where dry conditions can be
guaranteed, resin or organic glues may be used.
C. FRAMES WORK
The word framed shall mean and include all the best known methods of jointing
woodwork together by mortice, tenon, dovetail or other methods, and for forming all
necessary stops, mitres or mason’s mitres in members which are moulded, rebated,
etc.
A. PLUGGING
Plugging and fixing to walls in all trades shall be executed by “Rawlplugging” or
similar approved proprietary methods all in accordance with the manufacturer’s
printed directions. Hacking of holes and filling with timber plugs will not be
permitted under any circumstances.
B. CARPENTRY
(i) All carpentry shall be executed with workmanship of the best quality.
Scantlings and boards shall be accurately sawn and shall be uniform in
width and thickness throughout and shall be as long as possible and
practicable in order to eliminate joints.
(ii) All work shall be left with a sawn surface except where specified to be
wrot.
(iii) All work shall be accurately set out and in strict accordance with the
drawings, and shall be framed together and securely fixed in the best
possible manner with properly made joints. Provide all brads, nails,
screws, etc., as necessary and as directed and approved.
(iv) Actual dimensions of scantlings for carpentry shall not vary from specified
dimensions by more than +3mm – 1.5mm. Sizes and thicknesses of wrot
carpentry timbers are nominal, that is to say a variation of 3mm from the
specified sizes will be allowed from each wrot surface unless the thickness
or size is described as “finished” in which case no variation from the stated
thickness or size will be permitted.
JOINERY
C. GENERALLY
All joinery work shall be wrot unless otherwise described.
(i) Sizes and thickness of joinery are nominal that is to say a variation of 3mm
from the specified sizes will be allowed from each wrot surface unless the
thickness or size is described as “finished” in which case no variation from
the stated thickness or size will be permitted.
(ii) No joinery to be put in hand until the details have been supplied or
approved by the Architect and in all cases the details are to be worked to.
(iii) All joinery shall be executed with workmanship of the best quality in strict
accordance with the detailed drawings, mouldings shall be accurately and
truly run on the solid and all work planed, sand-papered and finished to the
approval of the Architect.
All arrises to be slightly rounded. All framed work shall be cut out, and
framed together as soon after the commencement of the building as is
practicable but should not be wedged up until the building is ready for
fixing the same and any portions that warp, get in winding, develop shakes
or other defects shall be replaced with new. In doors frames, etc., the heart
face of the timber shall be fixed away from the wall. As soon as required
for fixing in the building the framing shall be glued together with glue as
described and properly edged to pinned, etc., as directed.
(iv) All bends, fillets and small members shall be fixed with round or oval
brads or nails well punched in and stopped. All larger members shall be
fixed with screws, the screws let in and pelleted over with wood pellets to
match the grain.
(v) Cups and screws for fixing beads and fillets shall be spaced 150mm apart
and 25mm from angles.
(vi) All joinery immediately upon delivery to the site is to be stored and
protected from the weather.
(vii) All joinery is to be primed before fixing but no work is to be primed until it
has been approved by the Architect.
(viii) All fixed joinery, which is liable to become bruised or damaged in any way,
shall be properly cased and protected by the Contractor until the completion
of the Works.
(ix) When natural finish is specified, the timber in adjacent pieces shall be
matched and uniform or symmetrical in colour and grain.
A. SEASONING OF TIMBER
All joinery timbers are to be seasoned to an average moisture content of not more that
15%. The Contractor is to make available on site a meter for testing moisture content of
all timber delivered.
B. PREPARATION AND PROTECTION OF TIMBER
(i) All timber necessary for the Works is to be purchased immediately and
when delivered is to be openstacked for such further seasoning as may be
necessary. Preparation of the timber is to be commenced as early as
possible.
(ii) All timber and assembled woodwork is to be protected from the weather
and stored in such a way as to prevent attack by decay, fungi termites or
other insects.
C. SPECIES OF TIMBER
Only those timbers specified in these Bills of Quantities are to be used for the
Works, unless alternatives are authorised by the Architect in writing.
D. PRESSURE IMPREGNATED TIMBER
(i) All timber described as pressure impregnated shall be impregnated under
vacuum and pressure with ‘Celcure” wood preservative with an average
absorption of not less than 6.7kgs of dry Celcure salt per cubic metre. In
case of resistant species where this retention cannot be obtained the timber
shall be treated to refusal point. All treated timber shall be exposed to wet
conditions for at least 14 days after treatment has been carried out. All cut
ends, drilling or fabrications on the Site producing new surface shall be
thoroughly brushed or soaked with “Celcure B” salts applied in accordance
with the manufacture’s instructions.
(ii) Any other method of timber impregnation will only be allowed at the
Architect’s approval.
A. TIMBER BUILT INTO MASONRY
Ends of timber built into walls shall be thoroughly brush treated with creosote or
other approved preservative and clear air space maintained around the timber where
they adjoin the walls.
B. DIMENSIONS
Before putting in hand any joinery work, whether built-in or fixed later, the joiner is to
ascertain and check on site all dimensions, which affect or govern the joinery
work.
C. BLOCKBOARD
Blockboard shall be of approved local or imported manufacture, to B.S. 3444, glued
throughout and softwood or hardwood faced as herein after specified and equal to a
sample to be deposited with the Architect for approval and which when so approved
shall form the standard for the Works.
D. GUMPOLES
Shall be to the species eucalyptus saligna or eucalyptus maisenii, shall be of the
minimum diameters stated and shall be stripped of bark before incorporation in the
works.
The Contractors attention is drawn to the length of the poles, each of which must be in a
single length; splicing will not be allowed.
E. PRICING NOTES
Prices for joinery work shall include for slightly rounding all arrises of timber
members.
Prices for hanging doors must include for any type either folding, swinging or
sliding.
Prices shall also include for all necessary glueing, spiking, nailing, and screwing
whether specification mentioned or not.
Prices for items described as plugged shall include for fixing with screws.
IRONMONGERY
F. IRONMONGERY GENERALLY
(i) Ironmongery shall be fixed with suitable screws to match and prices shall
include for this.
(ii) All locks and ironmongery shall be fixed before the woodwork is painted,
handles shall be removed before the painting commences, carefully stored
and refixed after completion of painting.
(iii) All locks, springs and other items of ironmongery with movable parts shall
be properly tested, cleaned and adjusted where necessary to ensure proper
working order at the completion of the works and left in perfect working
order by the Contractor.
(iv) The keys of all locks shall have labels attached with door references
marked on before handing to the Architect.
A. PRICING NOTES
Prices for fixing ironmongery shall include for fixing before woodwork is decorated and
for removing lock handles, finger plates and the like and re-fixing and oiling after
decorating is completed.
METALWORK
B. MATERIALS GENERALLY
All materials shall be the best of their respective kinds, free from defects and all
works is to be carried out in the most workmanlike manner and strictly as directed
by the Architect. The materials in all stages of transportation, handling and
stacking shall be kept clean and protected from injury by breaking, bending or
distortion and weather action.
C. MILD STEEL
Mild steel shall comply with KS. 02-18 and B.S. 15.
D. BOLTS, NUTS AND WASHERS
These shall be fabricated from materials which comply with K.S. 02-18 and B.S. 15, and
each manufactured item shall comply with the appropriate standard.
E. TUBULAR RAILS, ETC.
Shall be galvanised mild steel “medium” duty to B.S. 1387.
F. HOLLOW SECTION TUBING
Square and rectangular hollow section tubing shall be hot rolled mild steel in
accordance with Grade 43 C of B.S. 4360.
G. FABRICATED WORK
All screwed work shall have full threads conforming to B.S. 21. Welded work is to
comply with the provisions of B.S. 538 and shall be carried out so that no distortion
to the members occurs and upon.
H. GALVANISED SHEET STEEL
To be the thickness specified and of approved manufacture to K.S. 06-02 best
quality mild steel sheets cold rolled close annealed patent flattened and hot dip
galvanised.
I. ALUMINIUM
Wrought aluminium shall be of the alloys described and shall comply with B.S. 1474 –
extruded round tube and hollow sections B.S. 1476 – extruded tube and hollow sections
B.S. 1476 extruded bars, rods and sections B.S. 1477 – plate.
A. SMITHING ETC.
All smithing and bending shall be soundly and neatly executed, care being taken not
to overheat.
B. FORGING
All straps, bolts and similar work shall be forged neat and clean from the anvil.
C. WELDING
All welding shall be neatly and cleanly executed and no excess weld metal at joints
will be accepted. All welds are to be ground smooth on completion and prices are to
include for this.
D. WORKMANSHIP
All structural steel work is to be erected in accordance with B.S. 449. “The use
of structural steel in Buildings”.
PLUMBING INSTALLATIONS
E. QUALIFICATIONS OF THE RULES OF THE S.M.M.
Jointing Pipes
(i) Notwithstanding the provisions of S.M.M. Clause Q.9 (b), the prices for all
galvanised steel screwed pipes shall be deemed to include for jointing with
hemp and red lead or “Boss white unless otherwise described and the prices
for all cast iron pipes shall be deemed to include for jointing with a gasket
of hemp and cold caulking compound unless otherwise described.
Provision of Holes
(ii) Notwithstanding the provisions of S.M.M. Clause Q.1 (g), the provision
of holes shall be deemed to be included in the description of fixing.
F. DEFINITIONS
(i) Painting
The preparation of surfaces shall be deemed to be included with the
description for painting. Specific requirements relating to the preparation of
surfaces are given in the WORKMANSHIP section of these preambles. In
the absence of specific requirement surfaces shall be prepared in the
manner recommended by the manufacturer of the paint being used.
(ii) Welding
In the absence of specific requirements the techniques and materials
employed in welding shall be selected with due regard to the character of the
work and the metals being connected.
(iii) Background reuiring plugging
The term ‘backgrounds requiring plugging’ shall mean any or all of the
backgrounds described in S.M.M. Clause Q.1 (h) (iv), and shall be deemed to
include the associated plugging.
(iv) Plugging
The term ‘plugging’ shall mean provision and fixing of hardwood or
approved proprietory plugs, or, at the Contractor’s option, fixing by
means of a cartridge operated rivet gun or other approved mechanical
means.
(v) Surface finishes
In the absence of specific requirements, the treatment and finish of pipe
fittings shall be appropriate to the finish of the pipes with which they are
associated.
(vi) Pipes sizes
The size of the pipe shall be the diameter of the bore.
A. GENERALLY
Execution of plumbing works
All plumbing work shall be executed in accordance with the best principles of
modern practice by a firm of fully qualified and registered plumbers. The
Contractor shall obtain the Architects written approval to the firm he proposes to
employ before the plumbing works are commenced.
The Contractor shall obtain the Architects prior written approval to the position of all
pipe runs, valve positions, control points, access points and the like for all plumbing
installations.
At the time of practical completion the Contractor shall prepare and hand to the
Architect four copies of plans and diagrams showing the positions of all pipe runs,
valve position, control points, access points and the like for all plumbing
installations. Such plans and diagrams shall be to the Architects approval, and
practical completion of the plumbing installation shall be deemed to have taken
place only after receipt by the Architect of such approved plans and diagrams.
All plumbing and drainage works shall be executed in accordance with the Regulations
of the Local Authorities. The Contractor shall give all notices and pay all fees
required thereunder. The amount of such fees shall be deemed to be included in
the Contract Sum, unless they are expressly included in these documents by way of a
Provisional Sum or Prime Cost Sum.
B. RAINWATER INSTALLATIONS
Plastic pipes
Plastic pipes, fittings and accessories shall comply with B.S. 4576 heavy grade PVC,
colour to be selected by the Architect: fixed true to line with straps supplied by the
manufacturer screwed to hardwood plugs with galvanised screws, and jointed all in
accordance with manufacturer’s instructions. Rubber sealing rings shall comply
with B.S. 2494 Part 2.
Fixing
Except where adequately restrained and supported by being built in, all pipes and
fittings shall be with one holderbat to each socket. Pipes less than 75mm diameter
shall be fixed 25mm clear of walls and those 75mm diameter and over 40mm clear
of walls. Holderbats shall comply with BS 416, Table 21 coated.
A. ASBESTOS CEMENT PIPES
Asbestos cement pipes are to be B.S. 582 with joints made in tarred hemp and 25mm
bituminous compound caulked in with slightly moistened neat cement.
Pipes are to be fixed clear of walls with approved bitumen dipped pipe clips.
B. GALVANISED STEEL TUBES AND FITTINGS
Galvanised steel tubing shall comply with B.S. 1387 with galvanised reinforced
malleable cast iron fittings complying with B.S. 143 and 1256 with B.S. 1256
threads.
Jointing – Tubing and fittings shall be seam-jointed using hemp and red lead putty of
‘Boss’ white.
Fixing – Tubes shall be fixed clear of walls or soffits, with galvanised malleable iron
brackets complying with B.S. 1494, Part 3 (or with hangers or special fixing where
so described), spaced at not more than 3 metres centres.
C. PITCH-IMPREGNATED FIBRE DRAIN PIPE, COUPLINGS AND FITTINGS
Pitch fibre drain pipes etc. shall be to B.S. 2760 and of approved manufacture.
Joints shall be made with straight couplings as indicated in the B.S. and the laying,
cutting and jointing shall be executed strictly in
accordance with the manufacture’s instructions.
Joints generally
All joints shall be perfectly smooth inside without excrescences.
Sleeves
All drains passing through walls or foundations shall have sleeves of cast
iron pipe of sufficient size to allow a 3mm clearance round the drain.
D. BRACKETS AND HANGERS
Brackets for supporting horizontal drains from walls or beams, shall be of
75mm x 75mm x 10mm coated steel tee with one end rounded up and of
sufficient length for the other end to be built in for a depth of 225mm.
Hangers for suspending drains from soffits shall consist of a pair of forged
50mm x 10mm coated steel half pipe saddles bolted together around the
one end forged into an eye to receive the bolt. The top of the bar shall
either be fanged for casting in, or shall be threaded with nut and plate
washer. Where fixed through floors the projecting end of the bar shall be
cut off flush with the nut.
A. WIRE BALLONS
Wire balloons shall be copper; mosquito proofed and shall comply with B.S.
416 table 22.
B. SANITARY FITTINGS
Sanitary Fittings shall be as specified. In the event that the appliances specified are
unavailable, the supply of alternatives which are at least equal in every respect in
of the Architect.
C. WORKMANSHIP
Any bead or feather formed when the pipe is cut, which reduces the internal
diameter of the pipe must be removed before the pipe is jointed.
Bends on copper or wrought iron pipes shall be formed on approved machine and in no
case to an internal radius of less than eight time the outside diameter of the pipe.
In no circumstances will the contractor be allowed to use elbows on pipes of 30mm
diameter and above.
All tubing exposed on faces of walls shall be fixed at least 25mm clear of adjacent
surfaces with approved holderbats built into walls not more than 2.0m apart and not
more than 1.0m for PVC tubing.
Pipes fixed in roof spaces or joinery shall be fixed with approved clips screwed to
timber members not more than 2.0m apart.
Easy bends on the line of piping shall be made with an approved bending machine; no
firebends will be permitted. Where elbows are required they shall be of round
pattern.
D. PIPE FIXED IN WALL CHASES
Where directed, pipes shall be fixed in chases in walling and secured with approved
holderbats built into walls not more that 2.0m apart.
E. FIXING TO WALLS
All surface fixings unless otherwise specified shall be carried out with “PHILPLUG”
or “Rawlplugs”.
The fixing holes shall be drilled with special mansory drill and not cut with a chisel
under no circumstances will the use of wooden plugs be permitted.
The Contractor shall include for making good all walling and surface finishes.
F. WASTES
Wastes are to be provided as directed by the Architect. Unless otherwise specified or
shown on the drawing sink, shower and bath wastes are to be of 38mm tubing and
lavatory basins of 32mm tubing.
The wastes shall be set to fall through an external wall and shall be jointed to a back inlet
gulley or have splay cut end set or discharge over a gulley.
A. TRAPS
Unless otherwise specified traps shall be brass to comply with B.S. 1184 and shall be
provided with screwed cleaning eyes.
Where “antvac” traps are specified or shown on the drawings, they are to be
“Grevac Senior” or other approved patent trap.
B. SOIL AND VENTILATING PIPES
Soil and ventilating pipes shall be 100mm diameter cast iron or UPV pipe as before
described and shall be provided in the positions specified or shown on the drawings
at the head of each main drain.
The top of the pipe shall be provided with an approved galvanised wire balloon
grating on UPVC vent cowl and shall finish at least 450mm above eaves or flat roof
level.
C. TESTING
The Contractor shall from time to time as required to suit the progress of the
building, air-test the plumbing and internal drainage in sections to the satisfaction
of the Architect, before any such work is covered. At the completion of the works
all soil pipes and branches and waste pipes and other parts of the internal drainage
works connected directly with any sewerage drain or sewerage drain ventilating pipe
or soil pipes, shall be subjected to a water test and be proved capable of resisting a
pressure of 1.5 metres head of water and the Architect may also direct that a sample
or any other test be applied to any other part of the drainage or ventilating system as
he thinks desirable. Everything necessary for these tests shall be supplied by the
Contractor.
D. CLEANSING
On completion of the works, immediately before handing over, the Contractor shall
cleanse thoroughly the whole of the system and prove that it is functioning freely to
the satisfaction of the Architect.
E. HABITATION CERTIFICATE
On completion, the Contractor shall obtain a ‘Habitation Certificate form the Local
Council and forward to the Architect.
F. HOT AND COLD WATER INSTALLATIONS
Galvanised steel tubes and fittings
Galvanised steel tubes shall comply with B.S. 1387 heavy grade for rising mains and
branches off rising mains, and medium grade for distributing pipes; except where the
latter are in contact with the ground when they shall be heavy grade. Fittings shall
be galvanised reinforced malleable cast iron fittings complying with B.S. 143 and
1256 with B.S. 1256 threads.
Jointing – Tubes and fittings shall be screw-jointed using hemp and red lead putty of
‘Boss’ white. Connections to flushing cisterns, bib taps and the like, shall be made
with copper or other equal and approved connectors to facilitate removal.
Fixing – Unless described as being fixed in chases, tubes shall be fixed clear of walls
and soffits with galvanised malleable iron brackets complying with B.S. 1494, Part
3 (or with hangers or special fixing where so described), spaced at not more than the
distance in the following tables.
SPACING OF FIXINGS
Size of pipe Maximum spacing in metres
13mm 2.00
19mm 2.50
25mm to 50mm 3.00
Over 50mm 3.50
A. PIPEWORK GENERALLY
Pipes shall be in the maximum lengths possible to avoid unnecessary jointing.
Pipes shall be fixed to sufficient falls to prevent air locks and to enable the
systems to be drained.
B. LEEVES
Where sleeves are required for pipes passing through concrete, or blockwork, they shall
be of galvanised steel tube of sufficient diameter to give at least 3mm clearance
around the pipe.
C. BRASSWORK
Drainage taps with loose keys shall comply with B.S. 2879 type B.
Ball valves - shall be ‘Portsmouth’ type complying with B.S. 1212 for high or low
pressure as described fitted with a silencer tube drilled with a 6mm hole above the
level of the overflow warning pipe. Floats not exceeding 150mm diameter shall be
plastic type complying with B.S. 2456; larger floats shall be copper type complying
with B.S. 1968, Class C. Bib taps shall comply with B.S. 1010 and shall be of brass
with fixed jumpers and where so described shall be chromium plated or shall have
nozzle screwed for hose union and locking arm.
Stop valves shall comply with B.S. 1010 and shall be of brass with crutch handles or
loose key where so described. Those in exposed positions shall have polished brass
bodies.
Sluice valves shall comply with B.S. 1218, Class 1 or as described.
Gate valves shall comply with B.S. 1952 Class 150 solid or split wedge and non-
rising stem.
D. TANKS AND CISTERNS
Store tanks shall be sectional pressed galvanised steel tanks of 4.5mm plate of
approved manufacture complete with cover inspection manhole. Tanks shall be
assembled entirely in accordance with the manufacturer’s written instructions.
Storage cisterns shall comply with B.S. 417, Grade A, galvanised with one piece
galvanised covers and shall be of the sizes specified or shown on the drawings
supplied with removable sheet iron covers with edges turned down 25mm to suit
exact size of tank.
Tanks shall have an overflow pipe of greater diameter than the incoming service
and shall be set to discharge 300mm beyond the external wall of the building.
The end of the pipe shall be splay cut and have galvanised mosquito proof coffee
gauze soldered on.
A. HOT WATER CYLINDERS
Hot water cylinders are to be manufactured locally from No. 12 gauge welded
mild steel, galvanised after manufacture, with domed top, feed connection and
immersion heater bosses.
The cylinder is to be lagged with approved diatomite and asbestos fibre
composition having a tested minimum insulating value of 0.60 grm calories heat
loss per second per square centimeter per degree centigrade at 100 degrees
centigrade, mixed and applied in accordance with the manufacturer’s
instructions, reinforced with small mesh chicken wire.
B. TESTING
Clean out storage cisterns and tanks, including removal of all swarf, fill and
test the whole of the hot and cold water installations, rectify all defects,
drain and leave in a clean, serviceable condition.
C. FIRE MAIN INSTALLATION - DRY RISING MAINS
Fire brigade
All work shall be to the satisfaction of the Local Fire Brigade.
Approval of fittings
All inlets, outlets, valves and other fittings shall be of a pattern approved by the
local water undertaking and where they so require, shall bear their stamp of
approval.
D. GALVANISED STEEL TUBE AND FITTINGS
Galvanised steel tubing for dry rising mains shall comply with B.S. 1387, heavy
grade, screwed and socketted, with galvanised malleable cast iron fittings
complying with B.S. 1256.
All changes f directions in the run of piping shall be made with standard bends,
springs or long turn fittings, elbows shall not be used. Tubing and fittings shall be
jointed with hemp and red lead putty of ‘Boss’ white.
E. INLET BOXES
Inlet boxes shall comply with B.S. 3980 rust proofed steel, except that the open
panel of the door shall not be glazed but shall be filled with a laminated reinforced
glass fibre panel as listed with the words ‘DRY RISER INLET’ bonded between
laminates.
A INLET BREECHINGS
Inlet breechings shall be constructed in gunmetal, flanged for attachment to the riser
and fitted with two inlets, each consisting of a 63mm instantaneous male coupling
conforming to B.S. 336 and a back pressure valve and removable blank cap secured
to the valve with a length of chain. The breeching shall be fitted with a 25mm drain
valve with black capped hose union.
B. OUTLETS
Outlets shall comprise a gate pattern valve constructed in gunmetal, flanged for
attachment to the riser, fitted with a 63mm instantaneous female conforming to B.S.
336 and a removable blank cap secured to the valve with a length of chain. The
valve shall have a clear waterway when open and the valve cover shall be securely
fitted so that it does not unscrew when the valve is operated. The spindle shall be not
less than 22mm diameter and shall have a gunmetal hand wheel approximately
150mm in diameter marked with “OPEN’ and “SHUT” directions. The outlet valve
shall be kept locked shut with a locking strap and padlock.
C. PRECAUTIONS AGAINST THEFT
All bolts and studs used in the assembly of dry rising mains and valves and exposed
to view, are to be spot welded, either on the head or thread.
D. GALVANISED STEEL TUBES AND FITTINGS
Galvanised steel tubes and fittings shall comply with B.S. 1387 with galvanised
reinforced malleable cast iron fittings complying with B.S. 143 and 1256 with B.S.
1256 threads.
Jointing – Tubing and fitting shall be seam-jointed using hemp and red lead putty or
‘Boss’ white.
Fixing – Tubes shall be fixed clear of walls or soffits, with galvanised malleable iron
brackets complying with B.S. 1494 part 3 (or with hangers or special fixing where so
described), spaced at not more than 3 metre centres.
E. RAINWATER OUTLETS
PVC rainwater outlets shall be manufactured to the sizes and profiles measured
herein from heavy grade PVC, with a minimum 75mm wide flange all round the top
for fixing to roof surfaces, fully bedded in hot bitumen and jointed to the PVC
rainwater pipes.
Fulbora type coated cast iron outlets, with grating, hook bolt and clamping device
shall be cast into concrete or built into concrete or built into blockwork in the
positions and to the elevation shown on the drawings, and jointed with caulked lead
to rainwater pipes.
F. TESTING
Rainwater installations shall be subjected to a water test and proved capable of
withstanding a pressure of 1.05m head of water to the satisfaction of the Architect.
Any defects are to be made good by the Contractor and the whole system left sound
and perfect.
A. SANTARY INSTALLATION
Bye-laws
All the work shall comply with the requirements of the Local Authorities bye-laws
and drainage regulations and shall be executed to the satisfaction of the Architect
and the Local Authority.
B. SETTING OUT
The position of all pipes runs, including joints and connections, holes and the like, shall
be agreed with the Architect before work is commenced.
C. POLYTHENE TUBING
The polythene tubing for cold water services shall be normal or heavy gauge as
required or specified to comply with B.S. 1972. Joints and fittings shall be in
accordance with the manufacturer’s printed instructions.
D. SPUN CAST IRON PIPES, CAST IRON FITTINGS AND ACCESSORIES
Spun cast iron pipes and sand cast iron fittings shall comply with B.S. 416
for medium grade coated pipes and fittings. Sockets and spigots shall be type B
on pipes and type A on fittings.
Access doors shall be oval type with asbestos washers and manganese
bronze bolts.
Jointing – pipe and fittings shall be jointed with a gasket of hemp and
tightly caulked cold with caulking compound.
E. TESTING
Dry rising mains shall be hydraulically tested to a pressure of 20Kg/sq. cm.
PAVINGS AND PLASTER WORK
F. QUALIFICATIONS TO THE RULES OF THE S.M.M.
Notwithstanding the provisions of S.M.M. Clause S2 (a) preparatory work such as
hacking concrete, racking out joints for key etc., shall be deemed to be included.
Prices for paving shall include for any extra thickness consequent upon the floor not
being finished to the true levels and also for all temporary rules and for all
formwork to stop pavings at openings or edges as required. Prices for tile and
similar paving shall include for any pointing to exposed edges.
Plastering to walls has been measured over concrete columns lintols, etc., flush with
wall face, and prices for plastering shall include for any necessary dubbing out
consequent upon surfaces not being finished to true levels.
MATERIALS
A. SAMPLES
The contractor shall prepare at his own cost sample areas of the paving, plastering
and rendering as directed until the quality, texture and finish required is obtained and
approved by the Architect after which all work executed shall conform with
respective approved sample.
B. CEMENT
Shall be as described in “Concrete Works”
C. LIME
Shall be as described in “Walling”
D. SAND
The sand shall be as described for fine aggregate in “Concrete Wrk” and shall be well
graded to a suitable fineness in accordance with the nature of the plaster or paving in
order to obtain the finish directed.
D. WATER
Shall be as described in “Concrete Work”.
E. WATERPROOFING, COLOURING AND HARDENING COMPOUNDS
All waterproofing, colouring and hardening compounds are to be used strictly in
accordance with the manufacturer’s printed directions.
F. BONDING
Bonding compounds, etc., for use in applying plaster and similar finishes direct to
surfaces without the use of backings or screeds are only to be used if approved by the
Architect and are to be used strictly in accordance with the manufacturer’s printed
instructions.
G. EXPANDED METAL LATHING
Expanded metal lathing shall be 22 gauge 9mm mesh ribbed lathing as B.S. 1369
dipped in asphaltum paint. The edges of sheets to be lapped 50mm and joints
staggered and sheets to be fixed at 500mm centres to all supports with heavy
galvanised staples, or wired with galvanised steel wire.
WORKMANSHIP
H. CHASES, OPENINGS AND HOLES
All chases, holes and the like which were not formed in the concrete or walling shall
be cut, and all service pipes shall be fixed and all hole and chases filled with mortar
before paving and plasterwork is commenced. In no circumstances will the
Contractor be permitted to cut chases, holes and the like in finished pavings or
plasterwork.
A. PROPORTIONS OF MIXES
A mix referred to a 1:4 shall mean 1 cubic metre (1498Kgs) of cement to 4 cubic
metres of sand and other mixes shall be construed in like manner.
B. MIXING
All materials for pavings and plastering must be measured in proper gauge boxes in
the proportions specified and mixed in an approved power driven mixer for not less
than two minutes per batch. The mixer shall be used as close as practicable to the
works and no partial set materials shall be used or remixed.
C. PREPARATION FOR AND FINISH TO IN-SITU PAVING
(i) Where practicable in-situ paving and screeds are to be laid while
the concrete is still green. When this is not practicable the
concrete is to be well washed and brushed perfectly clean with a
steel wire brush, to remove all laitance and to give a roughened
face as a key and then kept wet for at least seven days before the
paving is laid and on the day of laying the surface is to be only
damp with all surplus water removed and painted with cement and
sand (1:1) grout immediately before commencing the paving. The
grout is to be applied continuously in front of the paving and not
in large areas that will dry out before the paving is applied. All
paved surfaces shall be finished hard and smooth with a steel
trowel unless otherwise specified.
(ii) Paving shall be protected during the first stage of hardening from
the harmful effects of sunshine, dry winds, rain or water. In
exposed positions they are to be covered with well wetted layer of
saw dust, hessian or other approved material and this layer is to be
kept damp for at least seven days, during which period no traffic is
to be allowed over the paving. When floor tiles or similar finishes
are to be applied, care shall be taken to protect the screeds to
receive them. When no longer required as protection to the
surface the material is to be removed and the paving left clean and
perfect.
D. ROOF SCREEDS GENERALLY
Roof screeds are to be laid to falls and currents of 1:80 with a minimum thickness of
20mm at rainwater outlets, and are to be finished to the entire satisfaction of the
specialist executing the waterproofing to roof.
E. CEMENT AND SAND ROOF SCREEDS
Roof screeds are to be of cement and sand mixed in the proportions of 1 cubic metre
of cement to 5 cubic metres of sand. The surfaces of the screed is to be
trowelled perfectly smooth to receive other roofing finishes.
F. SCREEDS TO RECEIVE FLOOR AND WALL FINISHES
These are to be finished with a steel trowel to a hard smooth, true and level surface.
Screeds to receive tiles, etc. which are to be bedded in mortar are to be well scratched
to form a key.
A. CEMENT AND SAND PAVING
To be of cement and sand (1:4) laid in one operation and finished hard and smooth
with a steel trowel.
B. WATER PROOF CEMENT SCREEDS
To be as last waterproofed with “Sealocrete Double Strength Pre-mix Solution”
mixed at the rate of 2.25 litres to each 50Kgs. of cement.
C. PRECAST CONCRETE PAVING SLABS
To be all in accordance with B.S. 368. The slabs are to be of the sizes given herein
and bedded, jointed and pointed in cement lime mortar (1:2:9).
D. QUARRY TILE PAVING
Quarry tiles are to be 19mm x 150mm x 150mm, hard, well burned and of an
approved colour to be equal to a sample submitted to and approved by the
Architect.
The tiles are to be soaked in clean water and drained off before bedding and are to be
bedded and jointed in cement and sand (1:4) mortar with 1.5mm joints and to be
cleaned off with sawdust immediately after laying.
E. WOOD PARAQUET
Wood parquet flooring shall be approved hardwood as specified and executed by
an approved specialist subcontractor.
F. P.V.C. TILE FLOORING
Tiles shall be laid by an approved flooring Specialist to patterns as directed by the
Architect using adhesives recommended by the manufacturer in writing. The tiles
shall be laid with straight joints in each direction. Upon completion the floors shall
be thoroughly cleaned and twice machine polished using a polish recommended by
the tile manufacturer.
G. CERAMIC TILE PAVING
Ceramic tile pavings and matching skirtings and nosings are to be laid on
prepared screeds. The tiles are to be soaked in clean water for at least six
hours before use and bedded in cement and sand (1:4) approximately 3mm
thick with straight joints in each direction. Upon completion grout in
matching cement to match tiles and wash and clean down. Tiles are to be
cut with an electric tile cutting saw.
H. TERRAZZO TILE PAVING
To be hard, dense, pressed tiles manufactured from terrazzo as specified hereafter
and in colours to be selected by the Architect. The tiles are to be laid on a prepared
screed and soaked in clean water for at least six hours before use and bedded in
cement and sand (1:4) approximately 2mm thick with straight joints in both
directions. Upon completion grout joints in matching coloured cement and machine
grind and polish.
A. GRANOLITHC AND TERRAZZO PAVING AND WALL FINISHES
Generally
Construction joints between bays of pavings are to be straight and vertical and are to
coincide, as far as possible with those in the concrete under.
After spreading and before finally striking to screed levels the pavings, etc., are to be
lightly tamped, each stage of the laying operation is to be properly carried out at the
optimum degree of stiffness of the mix so that the aggregate remains correctly
distributed throughout the pavings, etc. and so finished that the surface is true to
level, dense smooth and free of laitance and other defects and blemishes. The use of
dry cement or sand to absorb surplus moisture will not be allowed.
The thickness of the pavings, etc., in these Bills of Quantities include for the
combined screed or backing and the Granolithic or terrazzo finish.
Screed and Backing
To be in cement and sand (1:4) and of appropriate thickness.
B. GRANOLOTHIC
(1) To be composed of 900Kgs. of cement to cubic metre 1:21/2 by
Volume of 6mm to 3mm with not more than 15% to pass No. 50 B.S.
sieve clean blacktrap chippings free of dust, laid or applied to screed or
backing whilst they are still green.
Paving to be 20mm minimum thickness granolithic laid on a screed to
make up full thickness specified and finished hard and smooth with
a steel trowel.
(2) Dadoes to be 9mm minimum thickness granolithic applied to a
backing to make up full thickness specified.
Polished granolithic to be finished with a metal roller and all surplus
Cement lightly brushed off when surface is sufficiently hard to resist
dislodgement of aggregate. When the surface is hard enough it shall be wet
ground using a machine until the aggregate is uniformly revealed and then
well washed with clean water. Any small voids or holes left in the
surface are to be filled with cement grout and rubbed down by hand.
Mouldings etc., not accessible to machines are to be hand rubbed and
polished with carborundum. After an interval of 1 to 3 days the
surface is to be finally machine
ground using a fine abrasive.
C. TERRAZZO
(1) To be composed of one part of Snowcrete, Colourcrete or other
equal and approved white or coloured cement to two parts (1:2) by
volume clean marble chippings well washed and free from dust.
The marble chippings may vary in colour and from 3mm to 20mm
dependant on the effect required and sample areas must be
prepared for the Architects approval.
(2) Pavings to be 20mm minimum thickness terrazzo laid on a screed
to make up the full thickness specified
(3) Dadoes to be minimum thickness 9mm terrazzo applied to a
backing to make up the full thickness specifies.
(4) Polished terrazzo to be finishes as granolithic (4) preceding.
(5) Washed terrazzo to be washed and lightly bruches before final
setting so as not to dislodge any agrregate but to leave a textured
surface.
A. DIVISION STRIPS
To be set in position before paving is commenced and embedded straight and true.
B. PREPARATION FOR AND PROTECTION OF PLASTER FINISHES
(i) All surfaces to be plastered or rendered must be brushed clean with
a wire brush and well wetted before plaster is applied. Concrete
surface are to be well hacked and stone or block walls and hollow
tile soffits are to have joints well raked out clean at least 10mm deep to
form a key before plastering or rendering. All plaster and rendering shall
be kept continuously damp for seven days after application.
Where plasterwork is specified in more than one coat the undercoat
shall be well scored with undercut scratches and shall be allowed to
thoroughly dry and set before application of the subsequent coat.
The plaster work shall be protected during the first stage of hardening
from the harmful effects of sunshine, dry winds, rain or water and
shall be kept damp for at least seven days.
C. REVEALS MOULDING ETC.
All reveals and returns shall be set accurately at ninety degrees or to splays as the
case may be and plastered at the same time as the wall face in which they occur.
Internal angles shall be slightly coved and external angles slightly rounded with
neatly formed mitres.
D. CEMENT PLASTER
(i) Where applied in one coat to be cement sand (1:4) not less than
12mm thick finished with a steel trowel or wood float as
hereinafter specified.
(ii) Where applied in two coats, the first coat to be cement and sand
(1:5) not less that 8mm thick and the second coat to be cement and
sand (1:3) not less that 4mm thick finished with a steel trowel or
wood float as hereinafter specified.
E. TEXTURED EXTERNAL CEMENT PLASTER
To be minimum 15mm thick applied in one coat and finished with a wood
Float to an uneven surface. The texture must be consistent with a sample
panel prepared under the Architect supervision.
A. INTERNAL LIME PLASTER
(i) To be applied in two coats of finish not less 12mm total thickness.
The rendering coat shall be in the proportion of cement, lime and
sand (1:2:9) and the finishing coat not less than 1.50mm thick shall
consist of fine sieved lime putty with 10% of cement thoroughly
incorporated immediately before use, trowelled hard and smooth with a
steel trowel and sprinkled with water during the process.
(ii) The first coat must be must be well scored to form a key and at
least fourteen days elapse between the completion of any portion of
the rendering coat and application of the finishing coat.
B. PLAIN TYROLEAN FINISH
(i) The first coat 13mm thick shall consist of mixture of 1 cubic
metre (1498Kgs.) of Portland cement with 10% of lime added by
volume and four cubic metres of sharp sand, applied direct by
means of trowel and brought to a level finish with a straight board
or rule used in all directions to leave no ridges.
(ii) The finishing coat shall be applied by the medium of a Tyrolean
spraying machine and shall consist of cement and sand, the
proportions of which shall vary with the fineness of the sand and
shall be ascertained by trial. Only sufficient amounts shall be
mixed as can be used within one hour.
(iii) The finishing coat shall be built up in layers to be a total thickness
of 6mm to 10mm to give an approved honeycomb texture and shall
be applied in such a manner as to avoid the layers merging into a solid
mass.
C. “TEXCOTE”
Texcote finish is to be carried out by Texciote Africa (Mfg) Ltd. of P.O. Box 18534,
Nairobi.
D. WALL TILING
(i) Glazed wall tiles shall be of sizes specified herein and in colours
to be selected by the Architect. For exposed edges and angles tiles
with one or two edges glazed shall be used.
(ii) Screed to receive tiles to be 10mm thick of cement and sand (1:4)
well scratched to form a key.
(iii) The tiles are to be soaked in clean water for at lease six hours
before use and fixed by bedding in cement and sand (1:3) with
1.5mm straight joints in each direction.
(iv) Alternatively tiles may be in bedded in “Richafix” or other equal
and approved tile fixing compound applied strictly in accordance
with the manufacturer’s printed instructions. Walls are to be dry
before tiles are fixed and tiles are to be soaked in water before use.
Tiling is to be set and closely straight jointed with 1.5mm joints.
If non-plug tiles are used cardboard or plastic spacer pieces are to
be used to obtain constant joint width.
A. SAMPLE
(i) The Contractor shall prepare samples areas of the paving,
plastering and rendering as directed until the quality, texture and
finish required is obtained and approved by the Architect after
which all work executed shall conform with the respective
approved samples.
(ii) Samples shall be prepared at least four weeks before the work is
commenced.
B. MAKING GOOD
The Contractor shall cut out and make good all cracks, blisters and other defects and
leave the whole of the plaster work perfect at completion. When making good
defects the plaster shall be cut out to a rectangular shape with edges undercut to form
dovetailed key all finished flush with face of surrounding plaster, all at the
Contractor’s expense.
C. GENERAL
Glass for glazing and mirrors shall be of approved manufacture and is to comply with
B.S. 952 in all respects free from flaws, bubbles, specks and other
imperfections.
D. CLEAR SHEET GLASS
The clear sheet glass shall be ordinary glazing quality.
E. PLATE GLASS
Polished plate and Georgian wire polished plate glass to be selected glazing quality.
F. FLOAT GLASS
To be “Pilkingtons” float glass or other equal and approved.
G. OBSCURED GLASS
To be of types described and as approved by the Architect.
H. MIRROR
To be selected glazing quality plate glass mirror s of approved manufacture and
fixed at all corners to walls with rawplugs and brass screws with removable
chromium plated dome heads.
I. PUTTY
(i) The putty for glazing to wood sashes is to be linseed oil
and powdered whiting free from grittness putty all as B.S.
544 (Type 1 putty).
(ii) The putty for glazing to metal windows is to be gold size
metal window putty specially designed for tropical use,
all as B.S. 544 (Type 2) putty or patent mastic putty if
approved by the Architect.
(iii) All putty shall be delivered on site in the original
manufacturer’s sealed cans or drums and used direct
therefrom, with the addition only of pure linseed oil if
necessary. No mineral or other oils may be used in the
putty except genuine linseed oil.
A. GLAZING
(i) Glass panes shall be cut to sizes to fit the openings with
not more than 1.5mm play all round.
(ii) The rebates of all windows shall be painted one coat
before puttying.
(iii) All glazing to wood frames shall be sprigged and glazing
to metal frames shall be clipped.
(iv) All glass fixed to aluminium windows to be fixed in
accordance with the manufacturer’s instructions.
(v) All glass, where fixed with putty is to be back and front
puttied and care must be taken to ensure that it does not
project beyond the sight lines of panes and is to be neatly
mitred at angles.
(vi) Putty which has not set hard within seven days must be
removed and the glass re-puttied at the Contractor’s
expense.
B. BEDDING STRIPS
Washleather, velvet, etc. bedding strip to edges of glass is to be of sufficient width
to be turned over 6mm to each side of pane and shall be trimmed to the sight lines
of the pane.
C. GENERALLY
Allow for removing all cracked or broken panes of glass, cleaning rebating and re-
glazing with new glass throughout the progress of the works and for cleaning all
glass on both sides and leaving perfect upon completion.
D. PRICING NOTES
Each pane of glass has been measured to the nearest 25mm above both with in
width and height. Louvre blades have been similarly measured in regard to length.
Prices for glazing shall include for painting rebates of frames before fixing.
PAINTING AND DECORATING
E. MATERIALS
(i) The primers, paints, plastic emulsion coating, are to be approved
by the Architect and the manufacturer must guarantee to give all
times any necessary technical advice called for by the Architect.
(ii) The materials for other finishes be of best quality available of
approved manufacture.
(iii) Before commencing painting, the Contractor shall submit to the
Architect for approval a list of all the brands of paints and
finishing including the necessary primers and undercoats he
intends to use and immediately upon being so approved orders
shall be placed and total requirements obtained for the works.
(iv) Once approved no other brand of material shall be used without
the express permission of the Architect in writing.
A. MORDANT SOLUTION
All galvanized metalwork to be painted shall first receive a coat of a proprietary
mordant solution.
B. KNOTTING
To be shellac knotting to B.S. 1336.
C. STOPPING
To be composed of linseed oil putty, white lead, and gold size suitably proportioned
and mixed.
D. WAX POLISH
Wax polish is to be furniture polish of an approved proprietary brand.
E. SUPPLY AND PREPARATION
(i) All paints, distempers, etc, shall be delivered on site intact in the
original drums or tins and shall be mixed and applied strictly in
accordance with the manufacturer’s printed directions. The only
additions which will be allowed to be made will be liquid thinners,
driers, etc, supplied by the makers for the purpose. No paint,
distemper, etc shall be thinned more than approved by the
Architect.
(ii) Paint for external work shall be of the special quality
recommended by the manufacturers for external use.
F. GENERAL WORKMANSHIP
(i) The priming and undercoats shall be the correct brands and tints
to suit the respective finishings coats all in accordance with the
manufacturer’s directions.
(ii) All surfaces must be thoroughly cleaned down prior to painting
and decorating work, and no external painting may be done in
rainy weather. All paint must be thoroughly well worked on and
excess of paint in any coat must be avoided.
(iii) All brushes, tools and receptacles are to be kept clean and free from
dirt or old paint and are to be thoroughly cleaned each time after use.
(iv) Each coat is to be well brushed into the surface so that every part,
including joints, angles, etc, is adequately covered, but care is to
be taken to avoid excessive or uneven thickness of paint film,
particularly at edges and in angles, etc.
(v) Each coat of paint, etc shall be properly dry and shall be well
rubbed down with fine sand paper and be brushed clean before the
next coat is applied. The paint work shall be finished smooth and
free from brush marks.
(vi) Where so required or directed, painting shall be in part colours
and picked out and cut in and prices shall include for this.
(vii) All ironmongery, metal or plastic plates and electrical outlets and
fittings and the like shall be removed before painting is
commenced, and re-fixed on the completion of the work.
(viii) No spray or roller painting will be allowed unless permission is
given by the Architect.
(ix) The contractor shall so arrange his programme of work that all
other trades are completed and away from the area to be painted
when painting begins.
A. SAMPLE COLOURS
All colours will be selected by the Architect from the B.S. Range of colours.
Samples and colour cards of all paints, distempers, and materials shall be submitted
for approval of the Architect before the same are applied and sample panels shall be
executed for the Architect’s approval where and when directed. Such samples when
approved shall become the standard for the work.
B. PREPARATION AND PRIMING OF PAINTED SURFACES
(a) Plastered surfaces
(i) Plaster surfaces are to be perfectly smooth, free
from defects and ready for decoration. All such
surfaces shall be allowed to dry for a minimum
period of four weeks and rubbed down with No.2
grade sand paper to remove trowel marks stains,
etc., after the priming coat all cracks and
imperfections are to be made good with
“Polyfilla” (or similar approved hard filler) well
rubbed down and then touched up with the
priming coat.
(ii) Priming for plastic emulsion paint shall be the
paint thinned with 25% water.
(iii) Priming for oil paint shall be with an alkali-
resistant primer
(b) Cement plastered, Concrete and Block wall surfaces
(i) Surfaces shall be brushed so as to be entirely free
of dust, dirt, loose material, etc., immediately
prior to decorating.
(ii) Priming for plastic emulsion paint shall be the paint
thinned with 25% water
(iii) Priming for oil paint shall be with an alkali-resistant
primer.
(c) Ferrous Metalwork
All surfaces shall be thoroughly brushed down with wire brushes to
remove all scale, rust, etc., and rubbed down with No. 2 grade sand
paper and brushed and left perfectly clean immediately prior to
decorating.
(i) Shop-primed Surfaces to receive oil paint shall
have all bare places touched up with approved
metal zinc chromate primer.
(ii) Unprimed surfaces shall be given one coat
primer as last.
(iii) Galvanised surfaces shall be treated before
painting with mordant solution. The surfaces
shall then be thoroughly washed down with
clean water, allowed to dry and primed as last.
(iv) Coated surfaces already treated with bituminous
solution shall receive an insulating coat of anti-
bitumen primer or shellac knotting.
(d) Asbestos cement surfaces
(i) All asbestos cement is to be thoroughly brushed
down immediately prior to painting.
(ii) Priming shall be with an alkali-resistant primer.
(e) Fibreboard Surfaces
(i) Surfaces shall be lightly brushed to remove all
dirt, dust and loose –particles and have all nail
holes or other defect stopped with an approved
stopping compound, rubbed down smooth and
left with a texture to match surrounding
material. Nail heads shall be treated with zinc
chromate primer prior to stopping.
(ii) Priming for plastic emulsion paint shall be the
paint thinned with 25% water.
(iii) Priming for oil paint shall be with an alkali-
resistant primer.
(f) Hardboard surfaces
(i) Priming for plastic emulsion shall be the paint
thinned with 25% water.
(ii) Priming for oil paint shall be with a thin oil
primer.
(g) Wood surfaces to receive paint
(i) The woodwork shall have all knots or resinous
parts carefully treated with self knotting a
luminium primer. All cracks, nails or other
holes shall be thoroughly cleaned out and after
priming, all such cracks etc., are to be filled with
matching hard stopping which is to be rubbed
down flush with the adjoining surface.
Priming for oil paint shall be with self knotting
aluminium Primer.
The bottom edges of all joinery work is to be
primed before fixing.
(iv) The back of all joinery work is to be primed
before fixing.
A. PREPARATION, PRIMING ETC. FOR WOOD SURFACES TO
RECEIVE CLEAR TREATMENT
(i) All wood surfaces to receive clear treatment such as varnish,
polyurethane etc., shall be rubbed down to a satin finish with fine
sandpaper immediately prior to application.
(ii) The first coat of polyurethane or similar clear treatment is to be
well rubbed in with a cloth pad and the successive coat applied by
brush. Each successive coat ( except final coat) to be lightly
rubbed with fine steel wool.
B. COVERING UP AND PROTECTING
Cover up all floors, etc. as far as is practicable with dust sheets when executing all
painting and decorating work.
C. LEAVE CLEAN
Paint splashes, spots and stains shall be removed from floors, woodwork, etc. and
damaged surfaces touched up and the whole of the woodwork left clean and
perfect upon completion to the satisfaction of the Architect.
REPAINTING EXISTING PAINTED SURFACES
A. GENERAL PREPARATION
The Contractor is to carefully examine all surfaces to be redecorated for sign of any
defects in the underlying structure. Signs of any dampness, alkali action and loose
or unsound plasterwork, loose putty etc., are to be reported to the Architect before
any further work on that area is put in hand.
B. PREPARATION OF PLASTERED SURFACES
a) To be repainted with plastic emulsion or distemper
After general examination of surfaces for defects as above, the surfaces are
to be washed and brushed down with a stiff fibre brush to remove dust or
dirt preparatory to applying paint and all small cracks are to made good
with hard stopping.
b) To be painted with oil paint
After general examination for surfaces of defects as above, the surfaces are
to be washed and brushed down with stiff fibre brush to remove dust or dirt
preparatory to applying paint and all small cracks are to be made good with
hard stopping.
Rub down paint which, in the opinion of the Architect, is sound, firmly
adhering and without sign of underlying defect, with waterproof glass paper
as required to form a good key, rub down crazed, flaked, peeling blistered,
loose and rough local patches as required to produce a fair and even surface
throughout, remove all defective paint and wash down with clean water.
Bring forward local areas from which paint has been removed and other
slight irregularities with alkali-resistant primer, filler and one undercoat, all
as previously described.
Touch up filling to cracks, etc., with alkali-resistant primer and an
undercoat, all as previously described.
C. PREPARATION OF METAL SURFACES
To be repainted with Oil Paint
Wire brush or scrub as required to remove all rust and all crazed, flaked, peeling,
blistered, loose and perished paint. The metal under such areas is to be left bare and
clean.
Paint which, in the opinion of the Architect, is soundly adhering and without sign of
underlying rust, may be left on but is to be well rubbed down to form a sound key for
the new paint.
All bare surface exposed by the above preparation are to be primed and painted one
undercoat before the main first coat is applied.
A. PREPARATION OF WOOD SURFACES
(a) To be repainted with Oil Paint
(i) Thoroughly clean all paint which, in the opinion of the Architect
is sound, firmly adhering and without sign of underlying defects
and afterwards rub down with pumice stone or waterproof glass
paper and rinse down with clean water. Cleaning is effected by
washing down with suitable detergents (of such dilution that the
paint is not adversely affected) followed by thoroughly rinsing
with clean water. The cleaning agent is to be applied from the
bottom upwards and the rinsing is to be from top downwards.
(ii) Thoroughly examine for defects in the woodwork and sterilize
areas on which there is mould, and re-putty sashes, etc. as
necessary.
(iii) Except as provided in (iv) hereafter, remove all which is crazed,
laked, peeling, blistered, loose and decayed or otherwise defective
by carefully burning off or removing with an approved paint
stripper well rub down as required to produce a fair and even
surface throughout and rinse down with clean water.
(iv) Rub down with pumice alone or waterproof glass paper all paint
which is sound apart from uniform chalking of the surface and
rinse down with clean water.
(v) Thoroughly clean out all cracks, crevices, open joints, holes, etc.
coat with appropriate priming paint and fill in with hard stopping.
When stopping has set rub down until flush with the adjoining
surfaces.
(vi) Cut out all loose knots and stop as described in (v) above and
thoroughly coat all exposed sound knots with knotting.
(vii) Touch up with priming paint and undercoat all surfaces which on
completion of the foregoing preparations are bare of paints and
bring forward local areas from which defective paint has been
removed and other slight irregularities with prime, filler and
undercoat as previously described.
(b) To be redecorated with Polyurethane
Thoroughly clean all existing surfaces and rub down with pumice stone or waterproof
glass paper and rinse with clean water.
B. PRICING NOTES
Prices must include for rubbing down with glass paper between successive coats and
all cuttings in connection therewith. Prices shall include for all work in parti-colours
and for all picking out and cutting in connection therewith.
EXTERNAL WORKS
A. GENERALLY
The specification of works and materials in this section which repeat similar work in
preceeding bills shall be deemed to be the full specification of work and materials
contained in the preceding bills.
B. MURRAM
To be clean hard murram free from loam, top soil or clay.
C. HARD FILLING
To be crushed rock, broken brick, broken concrete or other approved hard granular
materials broken to pass not greater than a 150mm ring or to 75% of the finished
thickness of the layers being compacted whichever is less and graded so that it can be
easily and thoroughly compacted by rolling. The filling is to be laid in layers each of
a consolidated thickness of not exceeding 225mm.
D. ROAD AND PARKING AREA CONSTRUCTION
(a) Preparation of Formation
(i) Properly shape formation surface and consolidate and regulate to
an even and uniform gradient parallel to the ultimate finished
surface.
(ii) All soft spots are to be excavated and filled with hard filling
thoroughly consolidated.
(b) Compaction of Filling
Each layer of hard filling is to be compacted with a smooth faced three
wheel or tandem roller of a weight to be specified by the Architect. Rolling
will continue until the Architect is satisfied that no further compaction can
be achieved but in no case to be less that eight passess of the roller.
(c) Surface finish to filling
The surface of filling shall be blinded with graded quarry chips sufficient to
fill all interstices and rolled as above to proper falls, gradients and cambers.
E. DOUBLE SEAL PAVING
(i) All loose material shall be brushed from the surface of the base
course which shall then be lightly dampened. The surface shall
then be primed with a bitumen emulsion at the rate of 0.85 square
metres per litre.
(ii) Approved 80/100 straight run bitumen shall be heated in a mobile
oil or wood fired boiler having a minimum capacity of 650 litres.
(Note - heating in a drum over an open fire will not be permitted)
and then shall be applied at a temperature of between 1700C and
1800C at the rate of 0.65 square metres per litre.
(iii) Immediately following the bitumen spray, evenly spread 13mm
blacktrap chippings at the rate of 55 to 65 square metres per ton to
give a constant spread and complete adhesion to the bitumen and
roll with a 6/8 ton Tandam roller.
(iv) After an interval of 24 hours, apply second seal as above only at
the rate of 0.84 square metre per litre and then apply a second
layer of 13mm blacktrap chippings and roll as described.
A. PREMIX SURFACE TREATMENT
(i) Stone
The stone shall be hard, dense stone of a uniform blue/grey colour and shall
be free from dust impurities, overburden or admixture of softer stone. It
shall withstand when wet a crushing stress of 4,000 Lbs. Per sq. in. and its
aggregate value shall not exceed 20%. It shall be crushed so as to provide a
material of generally cubical shape, and shall be screened to produce to sizes
specified below.
The grading of the road stone for the surface course shall be within the
following limits:-
(a) 39mm (nominal) chippings % passing
Min. Max.
65m square mesh 85% 95%
38mm " " 40% 60%
21mm " " 0% 5%
(b) 19mm (nominal) chippings
19mm square mesh 90%
100%
9mm " " 0% 5%
(c) 13mm (nominal) chippings
13mm square mesh 90%
100%
6mm " " 0% 5%
(d) Screenings
9mm square mesh 90%
100%
6mm " " 0% 5%
(ii) Bitumen Binders and Bituminous Products Generally
The grades of bitumen binders and bituminous products referred to below are usually
described, for the sake of convenience, in terms of the nomenclature used by "The
Shell Company of East Africa." Equivalent grades by other manufacturers will be
approved by the Architect provided that in his opinion, the product is of high quality
an equivalent specification.
Prime and lack Coats Shelmac M.C.O. or M.C.I.
First (seal coat) and Second (wearing surface) Coats
Maxphalte 80/100 or Shelmae 500/700
First (seal coat) and Second (wearing surface) coats
Maxphalte 80/100 or Shelmac 500/700
(iii) Priming Coat
Immediately on completion of rolling, the surface of the base course shall first be
well watered and then primed with Shelmac M.C.O. or equal approved at a maximum
of 6.50 S.M. per 4 litre in the full width of the base course. The work may then be
left and surfaced at the Contractor's convinience.
(iv) Bituminous Cold Aggregate Premix surface Treatment
(a) Bituminous cold aggregate premix shall be applied in two courses, a 38mm
compacted blinder course and 13m compacted topping carpet. Mixing shall be
carried out at 200/2250F in approved power operated plant which shall incorporate a
twin-shaft, paddle mixer. If stored the premix shall not be permitted to have its
temperature reduced below 1800F. Premix shall be spread within 3 hours of removal
from the mixing plant.
(b) 38mm Binder course shall consist of
Percentage
of weight
38mm nominal chippings 93%
Filler 3mm to dust 31/2%
Shelmac 31/2%
(c) 13mm Topping Carpet shall consist of:-
13mm nominal chippings )
two thirds)
Screening one third 92.25%
Shelmac 4.75%
(d) Laying
The Premix shall be laid to the required thickness using an approved machine, and
immediately rolled one pass 4/5 ton roller. After leaving the surface from 4 to 6
hours, the final compaction shall be applied in two passes of a 10/12 ton roller.
A. PRECAST CONCRETE KERBS CHANNELS AND QUADRANTS
(i) Precast concrete kerbs channels and quadrants shall conform in all
respects with B.S. 340.
(ii) They shall be set on 100mm thick concrete base 200mm wider
than their thickness and haunched up back face 100mm high with
similar concrete.
(iii) Kerbs and channels to curves are to be accurately, set out with
radiating heading joints.
B. PRECAST CONCRETE PAVING SLABS
To be precast concrete slabs of the sizes specified in accordance with B.S. 368,
bedded, jointed and flush pointed in cement lime mortar (1:2:9).
DRAINAGE
C. DRAIN TRENCH EXCAVATIONS
Generally
(i) Trenches to be in straight lines and falls as shown on Drawings or
as directed
(ii) The Contractor shall report to the Architect and obtain his
approval when secure bottoms have been reached and are ready to
receive concrete.
Any such work put in hand before receiving his approval shall, if so
required, be removed and new work substituted, after the Architect’s
approval to the excavations has been obtained, all at the Contractor’s
expense.
(iii) The Contractor shall keep all excavations free from water by
pumping, temporary drains or other means as necessary or
directed. Any work damaged by water shall be replaced at the
Contractor’s expense.
(iv) Where rock is used for back filling it is not to exceed 150mm
gauge and all interstices shall be properly filled in with small
pieces and fine binder.
(v) The first back filling in pipe trenches is to be of approved
materials, imported if necessary, free from rock or stone and to be
watered and carefully tamped over around the pipes until they are
covered to a depth of 300mm subsequent filling is to be in 150mm
layers, watered and rammed.
(vi) Mechanical rammers may not be used until the pipes have been
covered to a depth of 1 metre.
(vii) Any disturbances of or damage to the pipes during backfilling must
be made good by the contractor at his own expense.
(viii) Surplus materials is to be laid over the trench to allow for
settlement of filling and may depressions or subsidence below the
level of the adjacent ground shall be filled up, as and when
necessary, until the end of the Defects Liability period.
A. LAYING AND JOINTING CONCRETE BASE DRAIN PIPES
(i) Laying is to be commenced at points of junction with existing
drains or at points of discharge.
(ii) Each line of drain is to be laid in a perfectly straight line to even
gradient.
(iii) Before each pipe is laid, it shall be examined to ensure that the
bore is clean and any foreign material removed. Each pipe shall
be stuck with a wooden mallet to test for soundness, and any
cracked or damaged pipes rejected. Ends of all pipes must be
clean before jointing.
(iv) Immediately after jointing as before described, a tight fitting wad
or scraper shall be drawn several times through the bore of the
pipe joints are to be protected from injury by rain, soil, water, etc.,
until they have set hard.
(v) Plug open pipes and junctions, whenever work is suspended, to
prevent the entrance of rubbish during construction.
B. CONCRETE BEDS AND SURROUND, ETC, TO PIPES
(i) When pipes are bedded on concrete the bed shall be first laid to
correct falls and levels with recess formed in same for the pipe
socket so that the whole of the soffite of the pipe barrel bears
evenly on the bed.
(ii) When the concrete has set, a thin layer of mortar (1:2) shall be
spread on the bed to receive the pipe’s barrel, sufficient to ensure
that surplus is squeezed out when the pipe is laid and finally
adjusted to level. After jointing the recesses around sockets shall
be filled with concrete of the same mix as the bed and the
haunching or surrounding completed.
C. TESTING DRAINS
The contractor will be required to inspect and test each length of drain before any
refilling of the trench takes place.
D. FENCING GENERALLY
The level of the top of fencing is to be as directed by the Architect but is generally to
follow the mean level of the ground on the line of the fencing. Any minor
excavations on the line of the fencing to enable this to be achieved to be allowed for
in the rates.
A CHAIN LINK FENCING WITH CONCRETE POSTS
Fence posts to be concrete Class “D” finishes fair on all exposed surfaces.
Intermediate fence posts shall be paced at 3.00 metres intervals, to be of 125mm x
125mm section tapering to 75mm x 75mm at top and 2800mm long overall.
The post to be reinforced with four 8mm diameter mild steel bars with No. 12
S.W.G. wire binders at 600mm centres and six times holed for wires or fixing bolts.
Raking struts to be of 200mm diameter section and 3000mm long overall with one
end splayed to suit notch in main post. The strut to be reinforced with four 20mm
diameter mild steel bars with No. 12 S.W.G. wire binders at 500mm centres and four
times holed for wires or fixing bolts. At the junction with the main or gate post the
strut is to be bolted on with one 20mm diameter wrot bolt with head, nut and two
washers.
Main posts, spaced at 9.00 metres centres, and corner posts to be of 150mm x 150mm
section and 2800mm long overall. The post to be reinforced with four 10mm
diameter mild steel bars with No. 12 S.W.G. wire binders at 600mm centres, ten
times holed for wires or fixing bolts and twice notched as required to receive end of
raking struts. Two side faces of post to have set of angle cleats and vertical clamp
bars as last described bolted on.
Concrete filling around post bases to be in plain concrete Class “E”.
Intermediate and main post bases to be excavated to allow posts to be let into the
ground for a vertical depth of 750mm and filled with 600mm diameter x 400mm
deep concrete well packed around post, the excavated material to be part returned,
filled and rammed and the surplus removed.
Raking strut bases to be as last but let into the ground for a vertical depth of 600mm
and filled with 450 x 450 x 300mm deep concrete.
Barbed wires to be No. 8 S.W.G. galvanized mild steel fixed complete with all
galvanized staples strainers winding brackets and other necessary fittings. Fasten to
intermediate concrete posts with No. 16 S.W.G. galvanized annealed mild steel wire.
Tying wire for securing chain-link fencing to line wire to be No. 16 S.W.G.
galvanized annealed mild steel wire.
Chain-link fencing to be manufactured from No. 16 S.W.G. galvanized annealed
mild steel wire woven into 50mm mesh with barbed top and 2000mm high or as
specified. The fencing is to be supported by three single and one double (at top) lines
of line wire and fastened to each line at 900mm horizontal intervals with tying wire.
LANDSCAPING AND SITE DEVELOPMENT
B. BUSH CLEARING
All trees, stumps, shrubs, undergrowth and other vegetation shall be completely cut
down and all roots entirely grubbed up and burned at a central point. All arising will
be left on the site for use in the garden development. Where roots are grubbed up in
areas which are to remain at existing ground level the resulting holes shall be filled
up with approved material rammed in 150mm layers up to the existing ground level.
A. GRASSED AREAS
(i) Areas to be grassed shall be cleared of all debris and roots and dug
up to a depth of 300mm.
(ii) Where outcrops of rock or murram occur, these will be covered
with suitable soil to a depth of 150mm.
B. MAINTENANCE
The trees, grass and flowers shall be watered and maintained until well established.
The contractor is advised to include all this in his rates.
C. GRASS PLANTING IN THE WORKS
Grass planting over rock or compacted fill material
Where grass is to be established in areas where decomposed or solid rock or other fill
material exists closer to the finished surface than 200mm, the following grass
planting procedure shall apply.
The rock shall be removed to a depth of 200mm below the finishes surface. The rock
shall then be ripped or otherwise broken up to a further depth of 150mm and lightly
compacted; 200mm of selected red soil shall then be spread over the surface. The
whole shall then be lightly rotavated to obtain a homogenous mixture to a depth of
150mm. Prior to planting, the soil shall be raked and 50 gm each per square metre of
bonemeal and hoof horn meal shall be spread on the surface.
The grass shall be cuttings of approximately 200mm long and shall be planted at
150mm intervals, 150mm bured in the soil. Planting shall be carried out with the aid
of a wooden peg and the soil well rammed around the cuttings.
The grass shall be systematically watered, cut and weeded to maintain it in a healthy
state throughout the maintenance period.
The rate for grass planting over rock shall include for the ripping of the rock,
provision of grass and all subsequent materials, tools, etc.
D. TREES AND PALMS PLANTING
Pits shall be 0.9 metre diameter x 0.9 metre deep. The sides shall be undercut and the
soil mixture shall be as follows:-
4 parts approved red soil
1 part sewage sludge.
These shall be thoroughly mixed together on the mixing ground and specifically set a
side for the purpose. The mixture shall be filled into the pits in 300mm layers,
firming with hard earth rammers at each layer. The surface is to be shaped into a
bowl-depression 200mm deep to assist in watering.
The tree plants are to be at least 0.9 metre high when brought to the works for
planting.
In the two days before planting takes place, each pit is to be thoroughly soaked with
100 litres of water. The trees or palms shall be planted and sticked in an approved
manner, well watered and maintained throughout the maintenance period.
The rates for tree planting shall include for provision of plants and materials
described in this clause.
A. PLANTING SHRUBS
Pits for shrubs shall be 750mm diameter x 750mm deep. They shall be excavated,
refilled, planted, maintained and paid for identical manner to trees and palms. All
shrubs are grouped together and the tenderer is to give a uniform rate that covers the
cost of any of the shrubs.
B. HERBACEOUS BORDERS, PLANT BOXES AND SIMILAR AREAS
Plant boxes, herbaceous borders and similar areas shall be excavated, refilled,
planted, maintained and paid for in an identical manner to trees and palms, excepting
that four parts of forest soil shall be used in place of red soil and 50 gm each per
square metre of bonemeal and hood and horn meal shall be spread on the surface of
the soil mixture before planting.
C. BOUGANVILLEA HEDGES AND TABLES
Bouganvillea hedges and tables formed on fencing and fencing tables shall be planted
between 100mm diameter cedar fence posts in a pit 0.75 metre deep and 0.75 metre
diameter filled as described above.
For tables, one plant is to be planted every 10 square metres as directed by the
Architect.
Bouganvillea hedge plants are to be planted at 2.0 metres intervals. The cedar posts
are 600mm high and placed at 2.0 metres centres with barbed wire stacked at the top.
Bouganivillea plants are to be attached to the fence wires and strained into a hedge or
table in the course of the maintenance period to the approval of the Architect. The
plant pits are to be excavated, refilled, planted, maintained and paid for in accordance
with the requirements laid down for shrubs.
The rates for bouganivillea plants and hedges and tables shall also include for all the
materials and operations described in this clause. Fence for bouganvillea hedges are
measured lineally and fence tables are measured superficially over the area formed
by the outermost wires of the table.