Basement Construction Guide

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SITE GUIDE

siteB a s e m e n t

w a t e r p r o o f i n g

guide


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F o r e w o r d

This publication is one of a series related to basements for housing. It has been produced under the direction of the

Basement Development Group, which was initiated and is co-sponsored by the British Cement Association.

A c k n o w l e d g e m e n t s

The British Cement Association (BCA) is grateful to the British Structural Waterproofing Association (BSWA) for co-

sponsoring this publication. It is also grateful for the assistance and comments provide by members of the Basement

Development Group and to the considerable work of its Waterproofing Task Group in drafting and progressing this

publication. Thanks are also extended to all others who provided input to and comments on the preparatory drafts.

B a s e m e n t D e v e l o p m e n t G r o u p W a t e r p r o o f i n g T a s k G r o u p

B Aspin (Chairman), House Builders Federation

A K Tovey (Secretary), Tecnicom

F Atkins, National Housebuilding Council

D Burke, Zurich Municipal

M Clarke, British Cement Association

P Hart, Institute of Building Control

D James, Bovis Homes South West

A Jones, Stewart Milne Group Limited

B Keyworth, Architect

R S Reynolds, Institute of Clerks of Works

G R Sharpe, Association of Building EngineersP Trotman, Building Research Establishment

A K Tovey (Chairman), Tecnicom

S Brown, Sika Limited

V Connolly, Renlon Limited

M Falla, Booth Engineering Services Limited

Z Ginai, Marley Waterproofing Limited

P Hewitt, Vandex UK Limited

T Holloway, Renlon Limited

M Lenaghan, Servicised Limited

I J Moffat, Fosroc Expandilte Limited

J A M Padley-Smith, Mastic Asphalt Council and

Employers Federation Ltd

A J Parker, SCL Group Limited

M Radford, RIW Limited

S u p p o r t i n g T r a d e G r o u p sAutoclaved Aerated Concrete Products Association

British Structural Waterproofing Association

Concrete Block Association

Mortar Producers Association

Ready-mixed Concrete Bureau

Many construction activities are potentially dangerous, so care is needed at all times. Current legislation requires all

persons to consider the effects of their actions or lack of action on the health and safety of themselves and others. Advice

on safety legislation may be obtained from any of the area offices of the Health and Safety Executive.

48.059

First published 1994

ISBN 0 7210 1476 3

Price group D

British Cement Association 1994

Published by

British Cement Association

Century House, Telford Avenue

Crowthorne, Berks RG11 6YS

Telephone (0344) 762676

Fax (0344) 761214From April 1995 the code will be (01344)

All advice or informat ion f rom the Br i t i sh Cement Associa t ion i s in tended for those who wi l l evaluate the s igni f icance and l imi ta t ions of i t s contents and take responsibi l i ty for i t s use and

appl ica t ion. No l iabi l i ty ( inc luding tha t for negl igence) for any loss resul t ing f rom such advice or informat ion i s accepted. Readers should note tha t a l l BCA publ ica t ions are subjec t to revis ion

from time to time and should therefore ensure that they are in possession of the latest version.


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C o n t e n t s

Product ion: Words & Pages

I n t r o d u c t i o n

Scope

P r i n c i p l e s o f d e s i g n a n d i n s t a l l a t i o n

G e n e r a l

Contract details

Site information

C o n s t r u c t i o n c a t e g o r y

Further considerationsBasement and site drainage

A p p l i c a t i o n o f w a t e r p r o o f i n g s y s t e m s -

D O S a n d D O N T s

General to all systems

Category 1: Bonded sheet membranes

Category 2: Cavity drain membranes

Category 3: Bentonite clay active membranes

Category 4: Liquid-applied membranes

Category 5: Mastic asphalt membranes

Category 6: Cementitious crystallization active

systems

Category 7: Proprietary cementitious multi-coat

renders, toppings and coatings

Geocomposite drainage systems

G l o s s a r y

R e f e r e n c e s

2

2

3

21

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I n t r o d u c t i o n

The benefits of basements, and their viability and costs

were examined in a previous report(1 )

. This indicated that

they can be economically introduced onto most sites. In

particular, it showed they have clear advantages where

the ground is poor and might otherwise be difficult and

possibly uneconomic to build on. However, to ensure

success, particular attention must be given to the design

and construction of the basement and any necessarywaterproofing. This publication provides specific

guidance on the site application or installation of the

various waterproofing systems and comments on other

associated construction matters.

A companion publication, Base ment wa te rp ro of ing:

Des ign guide(2)

, gives design information to help the

builder or building designer decide which construction

technique and waterproofing method offer the best

solution, and to help them avoid unsuitable construction.

Scope

The details and comments in this publication relate to

the categories of structural waterproofing which provide

Grade 2 or 3 internal environments, as defined in

BS 8102, which are appropriate for residential basements.

A Grade 2 environment is for use as workshops, plant

rooms and other areas where the performance level

permits no water penetration but where higher levels of

water vapour would be tolerable and surface

condensation may occur.

A Grade 3 environment is for ventilated residential and

working areas which require a drier environment.

P r i n c i p l e s o f d e s i g n a n di n s t a l l a t i o n

G e n e r a l

Applying or installing a waterproofing system are

specialist tasks that are just as important as choosing and

specifying the system. The manufacturer should have

been consulted early in the design stage to ensure that

the most appropriate system has been selected. The

manufacturer will also be able to carry out the

installation or to recommend specialist waterproofing

contractors familiar with the system to be used.

Installation or application should not be left to

inexperienced workers.

The British Structural Waterproofing Association can

provide details of manufacturers of various waterproofing

systems and of appropriate specialist waterproofing

contractors.

Contract detai ls

The specialist waterproofing contractor should examine

the contract drawings and waterproofing specifications to

ensure the design requirements are completely

understood. Since the designer should have consulted

with the manufacturer of the waterproofing system

during the design, there should be no obvious errors in

the contract details. However, the important thing is that

the final construction should perform satisfactorily. The

specialist waterproofing contractor should therefore

establish that the waterproofing concept does enable a

continuous barrier to be created - or otherwise

2

adequately protects the structure - and is practicable to

install.

Unless otherwise agreed with the designer, the materials

and installation should be in accordance with the

specified details, and all work should be carried out to

the same high standards irrespective of the Grade of

internal environment. All junctions, service penetrations,

dpc/cavity tray junctions and laps in materials should be

formed according to the designers or manufacturers

details.

The specialist waterproofing contractor should not use

alternative waterproofing systems or membranes since

they may not be appropriate for the conditions. For

example, the system may have been selected to resist not

just wat er but a specifi c ground chemi cal. Sim ilarly, any

protection boards or screeds should comply with the

specifications and be positioned as on the drawings.

In essence, no alterations should be made to the

specified materials, their relative position and installation

sequence, without clearance from the designer or the

manufacturer of the waterproofing system.

Si te informat ion

Before the form of construction and the necessary

waterproofing system can be chosen, information must

be gathered on soil type, water tables and other relevant

factors. This is the designers responsibility.

The main contractor should find out from the designer

what the site conditions are - particularly the likely

severity of ground water conditions, and pass this

information to the specialist waterproofing contractor.

Sometimes, the main contractor may need to lower the

water table temporarily or permanently to enable

construction and waterproofing to go ahead.

Any lowering of the water table will need to be

maintained until the loads acting on the basement, from

either itself or in combination with the superstructure,

are greater than the forces that would be generated by

the water pressures as the water table returns to its

original level.

Although a site survey will have determined the general

nature of the site, there may be local variations. Any

significant differences should be brought to the attention

of the designer as they may create an additional hazard

not previously taken into account. Changes from

impervious to permeable soils may produce unexpected

water channels. Similarly, interception of previous landdrains or other elements could increase the amount of

water present. Any unexpected chemicals or suspect

materials should also be brought to the designers

attention.

Construct ion category

The structural walls will usually fall into one of the

following three construction categories.

Type A (tanked protection) structures will often be of

masonry construction, although plain or reinforced

concrete may be used. The latter may be in-situ or

precast. The structure is regarded as having no integral

protection against water ingress and so relies on the

applied waterproofing system to provide the necessary

control. Masonry walls may need a cement rendering or

flush pointing to product an acceptable surface for

subsequent application of the waterproofing system.


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The waterproofing system will , depending on its type,

tolerate certain construction cracks or minor defects. Fine

hair-line cracks up to 0.3 mm wide in reinforced

construction will generally be acceptable. Any larger or

unusual cracks should be brought to the designers

attention to allow for possible remedial action before the

waterproofing system is installed or applied.

Type B (structurally integral protection) structures will

generally be of reinforced or prestressed concrete. Since

they are specifically designed to be water-resistant,further waterproofing will be required only where

additional control against free water or water vapour is

considered necessary. In some instances, the additional

protection may be used to safeguard the structure from

aggressive chemicals. Again, any noticeable cracking or

defect should be brought to the attention of the designer.

Type C (drained protection) structures incorporate a

drained cavity in the basement. Although defects in the

outer leaf will not usually create problems, they may

allow more water to enter the cavity. If too much enters,

this might overload the cavity drain and lead to water

penetrating the basement. The drainage channels must

be properly formed and positioned, be free from

obstructions, and be approved under test. Any defect or

suspect area in the outer leaf should be raised with the

designer before the inner cavity drain system is installed.

The surface of concrete floors or oversite should be

prepared to suit the particular waterproofing system to

be used.

Further considerations

Control of condensation

Because window areas are often reduced, there tends to

be less natural ventilation in basements than in other

parts of the structure. The designer will pay particular

attention to this and detail specific heating and

ventilation measures. It is important that any ventilation

system is properly installed and not obstructed by

waterproofing systems inside the structure.

The waterproofing system must be installed where

indicated by the designer as otherwise there could be

excessive interstitial or surface condensation.

System restraint

Some waterproofing systems need to be restrained so

that they can resist the hydrostatic pressure. The mass

and thickness of such restraint must comply with thedesigners or manufacturers details.

Chemical barriers

An externally applied membrane may have been

specified to resist the effects of aggressive chemicals in

the soil. It must not be replaced by any other membrane

or system without the designers approval.

Mo ve me nt jo in ts

The designer is advised to eliminate movement joints in

the basement substructure wherever possible. Where

they are incorporated, details should have been includedin the contract drawings and must be followed exactly. If

the specialist waterproofing contractor finds movement

joint s with no speci fic waterpro ofing detail s, the designer

must be asked to provide appropriate details. On no

account should a waterproofing system be continued

directly across movement joints.

Construction joints

Where reinforcement crosses construction joints in

reinforced concrete structures, the joints are not

movement joints and most waterproofing membranes

may be directly placed across them. With Type B

construction, these joints will often be provided with a

waterstop, either within the concrete or on its surface.

Service penetrations

Any service penetration through the basement wall or

lower floor slab will need special details.

It is important to ensure that service penetrations are

correctly formed and sealed in accordance with the

specification or manufacturers instructions. On no

account should penetrations be made or their

waterproofing attempted without proper details being

followed and agreed with the designer and manufacturer

of the waterproofing system.

Ba se me nt a n d s i t e dr a ina g e

Sometimes, installing a waterproofing system may mean

that the area around the basement has to be drained. In

any case, it is generally good practice to provide

perimeter drains to enable any excess percolating water

to run away - for example to the downside of a sloping

site or to a lower soakaway.

Since such drainage may be an essential part of the

waterproofing measures, it is generally advisable to make

sure this has been installed before the waterproofing

system is applied or installed.

Application of waterproofing systems - DOs and DONTs

Each waterproofing system has its own characteristics and application methods. In addition, each has procedures

which should be adhered to (dos) and aspects which may later lead to defects or problems ( donts) . These are

listed by category on the following pages, followed by some dos and donts for geocomposite drainage systems.

General to all systems

1 Bonded sheet membranes

2 Cavi ty dra in membranes

3 Bentonite clay active membranes

4 L iquid-appl i ed membranes

5 Mastic asphalt membranes

6 Cementitious crystallization active systems

7 Proprietary cementitious multi-coat renders,toppings and coatings

Geocomposite drainage systems

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G e n e r a l

A: He al th & Safe ty

D O s

OBTAIN Health & Safety product and equipment data, and have available on site

HAVE protective clothing, cleansing creams, etc. on site

DISPOSE of release paper, cores, primer tins, etc. properly

STORE gas bottles in a compound with high, secure fencing

ENSURE adequate ventilation to interior during working (particularly when asphalting)

PROVIDE respiratory protection where necessary

OBSERVE good housekeeping and general hygiene guidelines

KEEP materials out of reach of children

D O N T s

DO NOT ignore Health & Safety advice

DO NOT leave waste on site

DO NOT burn scrap

DO NOT transfer materials into unlabelled containers

POSSIBLE CONSEQUENCES

Accidents - personal injury, prosecution

Third-party injury, prosecution

Irritation from smoke and dust

Improper handling and disposal of unidentifiable

materials and risk of injury

DO NOT expose materials to heat or flame

DO NOT dispose of waste or surplus materials

incorrectly

Fire, explosion (primers) and severe personal injury

Environmental/legal considerations

B: I n f o rm a t io n

D O s

ENSURE that detail drawings, manufacturers literature and site instructions are available to operatives on site

CHECK that all information and details are in accordance with the waterproofing manufacturers instructions

SEEK advice and guidance from manufacturer on installation procedures

ENSURE specification conforms with the manufacturers recommendations

CONSULT the manufacturer, if in doubt

D O N T s

DO NOT confine information to the site hut

DO NOT start waterproofing until all the available

information has been read and understood


Waterproofing failure

Leakage

DO NOT assume that a manufacturer has been

consulted in the design, even where specified. The

concept or design may be basically flawed (see

Ba se ment wa terp ro of in g: Desi gn gu id e)

Litigation

DO NOT apply membrane without consulting the Incorrect application leading to potential failure and

manufacturers literature. financial loss

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C: Associated works

D O s

ENSURE that associated works are co-ordinated and do not impede or damage waterproofing

CHECK that other products and methods are compatible

TAKE CARE not to damage system, but repair simple defects according to manufacturers instructions

ALWAYS refer to manual

PROVIDE for attendance of other trades where specified

ARRANGE for hoisting facilities and any necessary scaffolding or other plant

PROVIDE suitable surface for application

ENSURE that measures taken will not interfere with the watertightness of the system

DONTs

DO NOT proceed if unsure of next stage or of its effect

on work in hand

DO NOT drag steelwork across unprotected work

DO NOT expect installers to provide services normally

provided by other trades


Damage, leakage, or longer-term adverse reactions

between materials

Damage or leakage

Poor workmanship

DO NOT pierce or breach waterproofing system

DO NOT introduce non-specified chemicals, etc.

DO NOT introduce any necessary vibration, heat, cold

or pressure until the system will accept this

Leakage

Harm to waterproofing system

Damage to membrane by imposed loads

DO NOT change drainage details without considering

the waterproofing system

DO NOT mix waterproofing systems, even if specified -

refer to client, designer or manufacturer

DO NOT continue if the continuity of the membrane has

been broken

Development of water pressures incompatible with

forms of construction

Failure through incompatibility of hybrid systems

Damp/water penetration

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1 B o n d e d s h e e t m e m b r a n e s

1A: Storage and handl ing

D O s

STORE as required by the manufacturer

RECORD batch numbers to check shelf life

STORE upright

KEEP in controlled temperature

FOLLOW manufacturers instructions and check that all ancillary items, tools and protective clothing are present on site

DONTs

DO NOT leave out on site or allow rolls to become cold

or wet

DO NOT use after shelf life expired

DO NOT store rolls horizontally

DO NOT allow material to get too cold

DO NOT allow material to get too hot

DO NOT mix products and ancillary items from different

manufacturers

1B: Preparation of substrates


Difficulty in stripping release paper and probably poor

adhes ion

As above

Edges of sheet become damaged and rolls become

difficult to strip and lay

Material could lose its adhesion

May become too sticky and prove difficult to lay

Incompatibility or unsuitability, with no redress in case

of failure

INSPECT surface to be waterproofed. Does it meet manufacturers requirements for finish, imperfections and othercriteria?

CHECK whether in accordance with drawings, especially provision of chamfers at corners/edges and chases for

terminations

ENSURE that surface is free from all contaminants (mud, wet, release agents, curing compounds, etc.) and in

accordance with manufacturers requirements

AVOID awkward details

ALLOW enough time for curing

ALLOW for temporary weather protection in order to provide dry surfaces

PLAN works to prevent membrane being left exposed for long period of time

D O N T s

DO NOT accept just any degree of finish

DO NOT waterproof over blow holes, poorly

compacted concrete or where brickwork or blockwork

has not been flush pointed

DO NOT accept surfaces not in accordance with

manufacturers details (absence of chamfers/chases, etc.)


Membrane puncture under load

Membrane not sandwiched correctly

Leakage

DO NOT dress membrane around an impossible detail

DO NOT lay on uncured background

DO NOT take on the contract unless you are happy the

membrane will be protected and that a suitable lap will

be left to connect to

Leakage

Membrane not bonded to background surface

Your company will get the blame for foreseen leaks

6

D O s


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1C: Applicat ion

MAKE SURE the correct primer is applied, following the instructions for number of coats and coverage rate

ALLOW primer to dry for the required length of time before applying membrane

ENSURE that reinforcing strips, angle fillets, etc. are used at changes in direction and are as required by manufacturer

ENSURE that all specified laps are provided and are rolled down

ENSURE that all laps are weathered

FOLLOW manufacturers instructions for laying membrane

ALWAYS check what is required as a minimum loading coat, since the membrane is designed to be sandwiched

D O N T s

DO NOT omit primer on horizontal surfaces unless

agreed by manufacturer

DO NOT stretch the primer application

DO NOT prime more than can be waterproofed in the

same day

DO NOT omit reinforcing strips, etc. at corners to save

cost


Subsequent defects in unbonded sheets provide a path

for water ingress

Inadequa te bond

Contamination with site dust/condensation/rain resulting

in lack of adhesion

Leakage

DO NOT omit or skimp on edge or end laps

DO NOT just unroll and drop down a vertical surface

Leakage paths

Air pockets behind the membrane

1D: Protect ion and backfi l l ing

USE appropriate or specified protection and apply carefully to prevent damage

PROP or backfill in sequence when using board protection

USE specified backfill material

COMPACT in layers as specified

ALWAYS USE a suitable protection board, of the correct thickness to avoid damage, spot-bonded to the membrane

DISCUSS the backfilling procedure with the site manager or design team. If this work is to be done by others,

arrange to be present to check for site damage

ENSURE that the backfilling does not impede a lap joint that you may have to work from later

D O N T s POSSIBLE CONSEQUENCES

DO NOT store materials on unprotected membrane

DO NOT tip waste material as backfill

Leakage from punctured or damaged membrane

Settlement and downward displacement of protection

board and membrane

As aboveDO NOT backfill without compacting layers as specified

DO NOT apply protection to damaged membrane

without first making repairs

DO NOT leave a sheet membrane unprotected

DO NOT drill or puncture surface without checking with

the installer

Leakage failure

Subsequent problems, since damage - whether

intentional or not - often goes unrecorded

Loss of waterproofing integrity of the membrane and

potential for leakage

7

D O s

D O s


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2 C a v i t y d r a i n m e m b r a n e s


D O



DO NOT leave drainage sheets around on site Damage

DO NOT allow ancillary sealing tapes to become cold Difficulty stripping release paper and probably poor

or wet adhes ion

2B: Preparat ion of substrates

D O s

CHECK and remedy unacceptable leaks in concrete or masonry substrate before the system is installed

CLEAN horizontal substrate and remove all debris

CHECK there are no depressions in floor slab which may cause ponding

ENSURE slab drains to drainage exits and pump sump

D O N T s

DO NOT lay membrane over unswept substrate

DO NOT lay cavity former over uneven floor surface

2C: Applicat ion and f ini shing


Blockages

Damage and ponding, leading to leakage

D O s

CHECK total integrity of cavity drainage system and inspect membrane for damage before placing screeds or

blockwork finishes

ENSURE that mesh reinforcement (if required) for floor screeds is supported

ERECT walkways to support access and barrows for placing screeds

CHECK and clean out all drainage points/channels

ENSURE sump pump (where provided) is operational


DO NOT shorten recommended overlaps

DO NOT omit recommended sealing strips and tapes

DO NOT omit sealing washers for mechanical fixings

DO NOT store materials on completed installations or

traffic unnecessarily

Water and moisture penetration

As above

As above

Puncture of membrane

DO NOT allow fixing through finished floor screeds, or

unauthorised channels in the finished loading screed

DO NOT allow additional masonry wall ties without

sealing washers

DO NOT allow membrane and finishes over membrane

to be carried out by two different parties

Cavity membrane will not be loaded correctly

Leakage

A meaningful guarantee could not be issued by the

membrane installer

8


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D O s

CHECK integrity of cavity drainage system before proceeding

AT WALLS, construct non-loadbearing blockwork wall in front of cavity drainage system

AT FLOORS, keep to specified screed thickness, reinforced if required

ENSURE that reinforcement mesh is supported and has not damaged cavity drainage system while being positioned


DO NOT proceed until everything has been inspected

and any damage repaired

Water penetration at damaged areas

DO NOT use ties unless properly sealed

DO NOT drag reinforcing mesh across cavity drainage

sys tem

Water penetration at ties

Damage and perhaps water penetration

9


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3 B e n t o n i t e c l a y a c t i v e m e m b r a n e s


D O s

STORE materials off the ground

KEEP dry before use

USE gloves when handling loose bentonite

D O N T POSSIBLE CONSEQUENCES

DO NOT place materials in standing water Prehydration and need for replacement


D O

MAKE reasonably flat and free from voids

D O N T

DO NOT leave stones or voids larger than 50 mm


Waterproofing efficiency impaired

3C: Appl icat ion and f inishing

D O s

REFER to manufacturers fixing guide

BRUSH standing water from substrate or blinding

ALWAYS lap panels

PROTECT from heavy steelwork

LAY only what can be covered in one day

WET the cut surfaces


DO NOT lay panels in standing water

DO NOT place panels on unrendered masonry surfaces

DO NOT walk on wet panels

DO NOT drag heavy objects across panels

DO NOT leave exposed for more than 48 hours

DO NOT lay large areas and leave uncovered

Prehydration and replacement needed

Loss of bentonite into voids. Loss of efficiency

Need for replacement

Damage - loss of bentonite

Prehydration and need for replacement

Prehydration and need for replacement

10


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D O s

USE hardboard in specific circumstances (but not normally required)

USE sand if possible, but nothing larger than 50 mm (MOT Type II is acceptable)

ALWAYS compact well

D O N T s

DO NOT use plastic sheeting or prevent water

reaching the system


System takes longer to react

DO NOT leave large voids, or forget to compact Waterproofing efficiency impaired

1 1


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4 L i q u i d - a p p l i e d m e m b r a n e s


D O s

PROVIDE dry, safe storage away from sources of ignition

RECORD ba tch numbers

KEEP in controlled temperature

ROTATE stock

D O N T s

DO NOT STORE longer than 12 months

DO NOT USE beyond shelf life without consulting the

manufacturer

P O S S I B L E C O N S E Q U E N C E S

Some loss of solvents, causing increase in viscosity

As above

4B : Preparation of substrates

D O s

DRY surface to depth of 1-2 mm

REMOVE dust, grease, oils and other contaminants

ELIMINATE all hollows and voids

FLUSH-POINT masonry walls

REMOVE sharp edges or high points

REMOVE existing floor or masonry paints

PROVIDE 20 mm sand/cement fillet in all internal angles

FOLLOW manufacturers recommendations for surface flatness, keeping it generally within 3-4 mm

ALLOW for temporary weather protection in order to provide dry surfaces

PLAN works to prevent membrane being left exposed for long periods

D O N T s

DO NOT apply to wet surfaces

DO NOT apply to a dusty or flaking surface

DO NOT apply to open-textured surface

DO NOT tamp surface heavily


Membrane will not bond to substrate

Membrane will not bond to substrate or may not leave

the brush

Continuity of membrane will be broken

Will cause pooling in low points

12


15/24

4C: Appl icat ion and f inishing

D O s

PREPARE surface correctly

REFER to manufacturers recommendations in cold conditions

APPLY at published coverage rates

APPLY in two coats

ALLOW each coat to dry throughout its thickness

REINFORCE angles where necessary

ALWAYS employ a preferred applicator, who is conversant with the product

D O N T s

DO NOT apply when temperature is below 5C

DO NOT pour onto substrate or apply thickly

DO NOT sand membrane

DO NOT screed until cured

DO NOT leave exposed to UV light for more than

28 days

DO NOT apply the material too thinly


Surface may frosty, i.e. wet

Trapped solvent and failure to cure

Breaks continuity of membrane

Membrane will be absorbed into screed

Membrane will weather, become thin and brittle

Membrane will not function as designed but instead

will leak

DO NOT apply a second coat before the first is fully

cured


Will damage continuity of first coat and cause solvent

ent rapment

D O s

Externa l pro tect ion

USE bitumen-impregnated fibre board horizontally

USE geotextile drainage board vertically

Interna l ly

REINFORCE slab or screed horizontally

ADD masonry skin with 20 mm cavity filled with sand/cement mortar as work proceeds

In all cases

ALWAYS allow for suitable protection which should be provided by the company laying the membrane

ENSURE protection is firmly fixed according to manufacturers recommendations

MONITOR the backfilling process to reduce risk of damage


DO NOT lay protection boards loosely

DO NOT leave exposed to backfilling or unprotected

against following trades

Movement, exposing membrane

Damage to the membrane

DO NOT leave membrane unsupported internally Membrane will blow, leading to failure

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16/24

5 M a s t i c a s p h a l t m e m b r a n e s


D O s

PROVIDE dry, safe storage for primers, gauges, tools, etc.

POSITION plant close to point of application

PLACE mastic asphalt blocks tidily near to asphalt mixer

D O N T

DO NOT increase the distance that molten material is

carried


Material could cool down and become difficult to lay


D O S

PROVIDE base to specified levels, tolerances and finish

APPLY float finish to horizontal surfaces

ENSURE adequate chases

PROVIDE correctly prepared vertical surfaces

ENSURE all oils, greases and contaminates are removed from all surfaces

D O N T

DO NOT penetrate horizontal or vertical surfaces with

services


Leakage failure around pipes

5C: Ap p l i c a t io n

D O s

ENSURE all horizontal and vertical work is applied in three coats

PIERCE and make good any blows while mastic asphalt is still warm

ENSURE all succeeding coats follow the preceding coats without delay

D O N T s

DO NOT allow temperature of remelt to exceed 230C

for sustained periods

DO NOT lay membrane on wet background

DO NOT lay successive coats on cold or contaminated

preceding coats

DO NOT lay on dusty surfaces


Adverse effect on viscosity of bitumen

Unacceptable increase in blowing

Lack of bond and contamination between coats

Unacceptable increase in blowing

14


17/24


D O s

PROVIDE protective screed to horizontal asphalt work as soon as practicable after laying

PROVIDE vertical brickwork protection and concrete loading coat designed to withstand the expected water pressure

on internally applied tanking,

MAINTAIN sump with pump facility until all loading is complete - if water pressure present

D O N T s

DO NOT backfill externally without protection to the

vertical asphalt

DO NOT store materials, reinforcement, etc. on

unprotected membrane or allow it to be trafficked


Damage to asphalt by other trades, before and during

backfilling

Puncture damage or cracking

1 5


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1 6

6 C e m e n t i t i o u s c r y s t a l l i z a t i o n a c t i v e s y s t e m s


D O s

KEEP products in dry, well ventilated area

WEAR suitable protective clothing to prevent contact with skin, eyes, nose, throat, etc.

WASH off immediately if bodily contact occurs


DO NOT use materials once they have become wet or

ha rdened

Materials will not hydrate fully

DO NOT leave wet materials on the skin Burns to skin

DO NOT breathe in dust Burns to throat

6B: Preparation of substrates

D O s

ENSURE all surface contaminants are removed

ENSURE substrate is sound

ENSURE there is an adequate key

CONTROL suction


DO NOT ignore defects in the substrate

DO NOT leave surfaces soft or dusty

Cracking and debonding of the system

As above

6C: Applicat ion

D O s

ENSURE surface is correctly prepared

MIX strictly in accordance with manufacturers instructions

MAKE sure substrate is saturated, surface dry

STOP all leaks before applying

D O N T s

DO NOT apply to dry substrates

DO NOT apply to surfaces running with water

DO NOT apply while a dehumidifier is running


Cracking and debonding of the system

As above

Insufficient hydration


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D O s

ENSURE system is properly cured

USE appropriate protection when backfilling


DO NOT force-dry the system

DO NOT allow point loading in the backfilling

Cracking and debonding

Damage to coating

1 7


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D O s

18

7 P r o p r i e t a r y c e m e n t i t i o u s m u l t i - c o a t r e n d e r s , t o p p i n g s , a n d

c o a t i n g s


D O s

FOLLOW manufacturers shelf life and general storage conditions

STORE in sealed original containers, in frost-free conditions

WEAR protective clothing, and keep a copy of the manufacturers safety sheet handy

KEEP out of reach of children, and dispose of waste and surplus correctly

RECORD batch numbers of the additive to check shelf life

STORE all ancillary materials, cement and sand correctly

D O N T s

DO NOT allow prolonged skin or eye contact

DO NOT allow materials to freeze or be subject toextreme heat, or store in an unsuitable environment

DO NOT use materials past their shelf life

DO NOT allow materials to become contaminated


Health hazard

Material may become unusable and system ineffective

As above

Contaminated material, possible failure

7B : Preparation of substrates

STOP infiltrations of water or lower the water table before proceeding

ENSURE substrate is of sufficient structural quality and soundness

WET the substrate before applying any coating

REMOVE all surface applications such as plaster and paint

ROUGHEN or hack all the surface to produce mechanical key or use surface retarders when placing concrete

REMOVE all contamination, dust, etc.

IDENTIFY likely problems or defective areas and agree what will be done as regards repair

KEEP within prescribed temperature limits during cure

ALWAYS use the sand and cement recommended by the manufacturer

D O N T s

DO NOT apply materials to a frosted surface, or when

temperature is below 5C


Slow rate of cure and poor surface bond

DO NOT apply to unsuitable contaminated surfaces

DO NOT apply to uncured substrates

DO NOT use beyond shelf life

DO NOT use old cement or ungraded sand

DO NOT proceed until water infiltration is stopped

DO NOT apply to substrate of inferior structural qualityand soundness

DO NOT apply to incorrectly prepared surface

DO NOT apply to thoroughly dry surface

As above

Ineffective system, substrate movement or cracking

which may reflect through render

Mix will be incorrect and the system will not function

As above

Unable to apply system correctly to surface

Cracking and failure of system

Poor bond of system to substrate

Rapid drying out of material, causing poor surface bond


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22/24

D O

D O

D O s

D O

2 0

G e o c o m p o s i t e d r a i n a g e s y s t e m s

A: Storage and handl ing


D O N T s

DO NOT leave unused material around on site

DO NOT leave exposed to ultraviolet light for long

periods


Damage

Decomposition of geotextile fabric

B: Preparation of substrate

ENSURE, for horizontal application, substrate is laid to falls

D O N T POSSIBLE CONSEQUENCES

DO NOT allow trafficking before backfill or concrete

oversite is placed to horizontal areas

Damage to drainage composite

C: Applicat ion and f ini shing

USE correct geocomposite type and fixings to suit substrate

INSTALL geocomposite with filter fabric to soil face

ENSURE that geocomposite filter membrane extends to wrap drainage pipe or links to a fin or other drain

ENSURE drainage outlet is to lower side of structure and drains away from building


DO NOT allow use of dimpled drainage core directly

against soft waterproofing membranes

DO NOT allow mechanical fixing against waterproofing

membranes

Damage to waterproofing

Damage and leakage

DO NOT allow bonding tapes to become cold or wet

DO NOT use sharp-footed reinforcement spacers

directly on membrane

Difficulty in stripping release paper or poor adhesion

Damage and leakage

D: Protect ion and backfi l l ing

USE approved backfill material and compact in layers as specified

D O N T

DO NOT use clay or chalk soil as backfill


Clogging


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G l o s s a r y

Air dry

C o m b i n e d s y s t e m

Construction joint

D a m p

D a m p - p r o o f

Damp res i s tance

Damp-res i s tant

Dra ined cav i ty

Expansion jo int

External


External (reverse)


Free-dra in ing

High water table

Hydros ta t ic head

Hydros ta t ic

pressure

Integra l

pro tect ion

Kicker

Kicker les s

cons truct ion

When the surface humidity of a

material is equal to that of the

ambient surrounding air

Two or more waterproofing

systems used together

Joint formed in-situ, for example in

concrete, when continuity is not

possible

The condition of a material when

wetter than air dry

Impervious to moisture, not

permitting moisture to enter

The ability of a material to exclude

moisture

Having a high resistance to

moisture penetration

A continuous cavity which

intercepts and drains away

incoming water

Joint that permits relative

movement caused by expansion

and contraction due to changes of

temperature or moisture

Where the waterproofing system is

positioned and placed against theoutside face of the main structure

Where the waterproofing is

positioned outside the main

structure but placed against the

enabling works

Ground through which free water

rapidly drains away

Where the water table is above the

underside of the lowest floor level

Water pressure, expressed as an

equivalent depth of water

The water pressure exerted as a

result of a hydrostatic head

Where the structure itself provides

the necessary protection to the

passage of water

Small concrete upstand, cast above

floor level to position wall or

column formwork for the next lift

A mechanical means of retaining

formwork in position, eliminating a

kicker

Loading coat

Low-permeabi l i ty

Low water table

M e m b r a n e

Moisture

Perched water

table

Protection layer

S a n d w i c h e d

waterproof ing

Vapour check

Vapour resistance

Vapour-resistant

Variable water

table

Water

Waters top

Waterproof

Waterproof ing

s y s t e m

Water-resistant

Water vapour

A material applied to the

waterproofing membrane to enable

it to resist hydrostatic pressure

Resistant to water penetration

Where the water table is

permanently below the underside

of the lowest floor level

A material which forms acontinuous effective barrier to the

passage of water

Water in the form of vapour as well

as liquid

Where, because of insufficient

permeability of a soil, percolating

water is held above the underside

of the lowest floor level, resulting

in hydrostatic pressure

An element used to provide protection

to a waterproofing system

Where the waterproofing system is

between the two non-tied leaves of

the main structure

A continuous vapour-resistant layer

The ability of a material to resist

vapour penetration

Excludes water and has a high

resistance to vapour penetration

Where the water is occasionally

above the underside of the lowest

floor level

Water in its liquid form

A product or system, placed in-situ,

to prevent the passage of water

through a discontinuity or joint in

site-placed concrete

Impervious to water, not permitting

water to penetrate

The total method or combination of

materials used to create a

waterproof protection

Having a high resistance to water

penetration

Water in its gaseous form

R e f e r e n c e s

1. BRITISH CEMENT ASSOCIATION. Options for quality in

houses: Basements 1 - benefits, viability and costs.

Slough (now Crowthorne), British Cement

Association, 1992. 37 pp. (Ref. C/10)

2. BRITISH CEMENT ASSOCIATION. Basemen t waterproofing:

Desi gn gu id e. Crowthorne, 1994. 20 pp. (Ref. 48.058).

2 1


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BASEMENT WATERPROOFING: SITE GUIDE

BRITISH CEMENT ASSOCIATION PUBLICATION 48.059

British Cement Association

British

StructuralWaterproofingAssociation

Documents

Basement Construction Guide