A PAPER WRITTEN TO ASSIST THOSE WHO MAY BE CONCERNED IN THE FINISHING OF CONCRETE SWIMMING POOL’S

8/3/2019 A PAPER WRITTEN TO ASSIST THOSE WHO MAY BE CONCERNED IN THE FINISHING OF CONCRETE SWIMMING POOLS

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SWIMMINGPOOL

RENDERING&TILING

INTHEUK,(POOLFINISHING).

ByDAVIDCOULSON APAPERTOHELPANYONECONCERNEDWITHTHERENDERING&TILINGOFSWIMMINGPOOLS

DIY,POOLTRADE,BUILDER,ORSTUDENTOF

CONSTRUCTION.

WWW.DIAMONDPOOLFINISHERS.CO.UK

[ C o m p a n y A d d r e s s ]


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SWIMMINGPOOLRENDERINGANDTILINGINTHEUK,(POOL

FINISHING)BYDAVIDCOULSON

HelenCoulson?SX


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THEFOLLOWINGARETHEMOSTPOPULARSWIMMINGPOOLTANKBUILDMETHODSEMPLOYEDTODAY

FOLLOWINGMATERIALMETHODS

1) SHOTCRETE,thiscan be defined as a mortar or concrete, pneumatically

projected at high velocity through a pressure resistant conveying line

onto a surface, where it is compacted on impact.

2) BLOCKWORK, reinforced concrete blocks, or reinforced patent block

systems,

Cavity reinforced concrete blocks containing reinforced concrete.

3) SITE CAST OR POURED-IN-PLACE reinforced concrete using

formwork /shuttering

THE SWIMMING POOL SHELL / BASIN / TANK

Swimming pools are deemed water-retaining structures whichever method of

construction is utilized and shall be designed and installed to be capable of

meeting the water tightness criteria in accordance with the specifiers

instructions

A WATER TIGHTNESS TEST should be carried out BY THE

MAIN CONTRACTOR prior to the commencements of any of

the SWIMMING POOL FINISHERS CONTRACTOR WORKSare commissioned, (obviously the TANK should pass the water

tightness test before the commencement of the finishers

works), THE BASIC STRUCTURE SHOULD BE

WATERTIGHT. And confirmation must be obtained in writing

before commencement of the finishing works.

LINING / POOL FINISHING WORK

The lining /finish of a swimming pool tank with sand and cement /mosaic / tile

or pool plaster materials, will requires the exceptional skills sets and specific

experience of a highly skilled swimming pool finishing contractor such as

www.diamondpoolfinishers.co.uk therefore, when placing your order for the

finish, one should not so much look for the lowest bidder, but consider the

expected quality, efficiency and reliability of such specialist contractors

THE SWIMMING POOL TANK /SHELL /OR BASIN MUST BE

Left to fully cure, before any pre finish inspections take place


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THINGS THE LINING CONTRACTOR WILL NEEDS TO CHECK THE

POOL TANK (SUBSTRATE) FORAnd objections should be made to the main contractor especially if any of the

following are found, IN WRITING!

1) Considerable unevenness

2) The substrate surface offering insufficient mechanical key (a constant

problem with site cast or poured tanks)

3) Efflorescence

4) Cracks from tensile stress or setting

5) Oily surfaces (again site cast or poured tanks from shuttering oil)

6) Visible reinforcement or salient metal parts (proud of the substrate)

7) Particles of shuttering timber

8) Algae (if the pool tank has been left to stand for a long time)

9) Dust and debris (must be removed)

10) Leaks or fissures in the tank

When the above preparations of the tank to be lined have been addressed


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and you are satisfied, then you can commence with the next stage, after a

good sweeping and cleaning out, this will be

SAND AND CEMENT RENDERING /SCREEDING

It must be said at this point that if it is possible to construct the tank to

a high degree of dimensional accuracy so that the tile/mosaics can befixed in (the DIRECT METHOD), then there is no need to apply a

render and screed to the tank, (this is very unusual), and most

swimming pool tanks are rendered/screeded

Ideally it is important in swimming pools that the render, screed, and tiling is

carried out by the same specialist contractor such as

www.diamondpoolfinishers.co.uk

The walls to be rendered should be clean and free of any loose or dusty

material, and given a good damping down with CLEAN water,

An SBR (a white styrene butadiene emulsion used to improve the

properties of cement renders, screeds and mortars. It is also used in

conjunction with Construction Chemicals Tanking Slurry as a priming

coat or tight render basecoat. Used with Sulphate resistant cement it

will resist the movement of salts within the wall). This is mixed with

OPC (ordinary Portland cement) until it is a slurry, then painted onto

the wall, just prior to the first application of the render scratch coat. This

is about 9mm in thickness and is evenly applied all over the wall, then

scratched with a combed scratching tool. This is designed to leave an

indented wavy pattern all over the wall (mechanical key), to enable the

next coat over the top of the scratch coat to tie into and mechanically

bind to this coat. The next coat or floating coat should provide a flat

level and true surface ready to receive the finishes. This is achieved

when the floating coat is spread about 9mm thick all over and on top of

the scratch coat, it is ruled-off with a straight edge. The low spots are

filled in and ruled flat all over. It is left to tighten-up, then rubbed-up

with a plastic float, then a trowel over to close it up and leave a smooth

surface finish, ready to receive tiles.


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Any external sharp angles in the pool tank, should be avoided if possible for

obvious reasons, if these have to be incorporated then do not use any form of

metal angle-beads to form them, (not even stainless steel) as they will all over

time corrode and oxidize under the tile layer. This will lead to tiles (de-

laminating from the render/screed surface over time.

Pool finishers would use the reverse RULE system to form any external

angles, as practiced by www.diamondpoolfinishers.co.uk

Most professional pool finishers will prefer to quarter-round any external

angles by (reverse mould template) so as to give the correct radius for the

mosaic size they are using on a particular job.

The constituent materials for the cement-based wall render and its

preparation and its application for both coats scratch /floating coats shouldcomply with the recommendations given in BS8481: 2006, BS13914 AND

BS5385-2: 2006 AND BS5385-4: 2009 where appropriate

(FLOOR SCREEDING) the laying of any cement-aggregate mix in the

horizontal, to a surface that will probably be walked upon.


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SCREEDING THE FLOOR OF THE TANK, USING THE (BONDED

METHOD)

First, PREPARATION is to scrape the floor over and sweep up any loosedebris. Wet the floor over with water, then scrub the same SBR/OPC mix as

for the bonding of the walls into the floor, just prior to laying the fresh screed

mix in to the wet bonding mix. This is painted/scrubbed into the substrate

concrete; this process is called (GROUTING-IN). Lay long bands of the

(PRE-MIXED) OR (HAND MIXED) fresh screed around the outer wall/floor

intersection edges at least 600mm wide. Rule-off flat, level and true. One

band/strip is laid down through the centre of the tank, these are used to work

from, to keep your bays level, flat and true. Work your way out of the pool in

alternating bays, as on a chessboard, so as to keep a wet working edge.Rule off and float over with your plastic float. Close up with your steel trowel


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as you go, until the floor is laid. The screed should be laid in accordance with

(BS8204-1) TOLERANCES should be no more than 3mm under a 2 meter

straightedge.

CURING /DRYING. Once laid all screeds should be correctly cured by

covering over with an impermeable membrane for at least 7 days or

longer if possible. Once cured the screed should be allowed DRY for a

further 3 weeks before installing the tiling. (At this point it is worth

mentioning that CURING AND DRYING ARE TWO SEPARATE

PROCESS). Adequate periods of time should be allowed as drying

shrinkage is the most often encountered cause of any subsequent

rendering/tiling failure

MOVEMENT JOINTS

Any movement joints, should be continued thought the screed/render and into

the tiling. This would also apply to movement joints in the walls sub-base, in

accordance with BS5385-1 or BS5385-3

Movement joints, as are recommended in BS5385-4, should be sited at the

intersection between the wall /floor/any corners of the pool tank and at any

change in the plane of the floor of the pool tank. No movement joint should

come to a dead end.

This is a good example http://www.youtube.com/watch?v=8NHgu7ij5NA of

one reason movement joints are essential in a swimming pool tank.

Movement joints should be placed at a distance of no greater than 6.5 meters.

At this point I would like to say that SPECIAL CONSIDERATION would need

to be given to the following:

1 DECK LEVEL types of pools

2 INFINITY EDGE types of pool

3 SALT WATER / SEA WATER types of pool

4 HYDROTHERAPY types of pool

5 COMPETITION types of pool

Concrete swimming pools that are intended for holding types of water that will

attack concrete, such as thermal, mineral or sea water, as well as medicinal

brines, must resist a considerably higher corrosive stress than ordinary

swimming pools. In these cases it is important that all the cement-based

materials are shielded from these media, by the application of a suitable

bonded lining


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SWIMMING POOL TILE FINISHES (FIT TO BE USED IN A

SWIMMING POOL AS A LINING). The choice of tiles or

mosaics for utilization in the swimming pool tank is an area,

which demands careful consideration prior to specification.

The surface finish to a swimming pool has to serve several functions TECHNICAL REQUIREMENTS

Ceramics as with other materials for use within the swimming pool tank need

to be technically fit for purpose. Bla or B1bBSEN14411.

They should have low water absorption of 3% or less if possible

Either extruded type AlaAlbBSEN14411 or dry pressed type

Product suitability should be sought in writing from the supplier and

manufacturer

Other areas to consider during your selection of tile should be safety. Tiles

must have adequate SLIP RESISTANCE for location of use. The tile

supplier / manufacturer must confirm their fitness for purpose.

AESTHETIC REQUIREMENTS are usually a matter of

personal choice, but some competition pools require special

thought for ASA or FINA accreditation. So check this out.

MOSAICS

When fixing mosaic that has been assembled with a backing material it is

essential that reference should be made to BS5385-2:2006 CLAUSE 5.3

which states that:

For a mosaic that has been assembled with a backing material, it is essential

that: A) the backing material and its adhesive does not occupy more than

25% of the area of each tessera; the critical factor is the spread of the

adhesive over the back of the tesserae;

B) the backing material and its ADHESIVE does not deteriorate in service and

that they are compatible with the mortar or adhesive bed in accordance with

the manufacturers instruction.

http://www.infotile.com/pdfFile/advicetopic/48201031834.pdf This is a very

good source of reading that we would recommend for anyone

ADHESIVE SPECIFICATION

For most areas of wall and floor tiling throughout a swimming pool installation,

POLYMER modified cementatious adhesives are recommended.

Where it is known that aggressive water conditions are present, especially

where mosaics are used, then fixing and grouting with a REACTION RESIN

product is advised. Ref to BS EN 12004; 2007 should be consulted. At this

point, it is worth advising that the water local to the swimming pool build, is

checked and tested for suitability.


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PREPARATION OF ADHESIVES

When working with hydraulically setting thin-bed mortars, (THE

MANUFACTURERS INSTRUCTIONS MUST BE STRICTLY OBSERVED)During the preparation of the thin-bed mortar, clean tools and clean / fresh

water must be used. The prepared mortar should be lump-free and of a

uniform, plastic consistency.

The preparation of the mortar should be carried out by means of electrically

operated agitators. The maturing time indicated by the manufacturer should

be adhered to. The prepared mortar must be used within the POT-LIFE. Any

mortar that has begun to cure MUST not be made workable by the addition of

water, but MUST be discarded.

ADHESIVE APPLICATION. The thin-bed mortar is applied

using the flat edge of the correct sized combed trowel onto

the substrate as in this example

http://www.youtube.com/watch?v=pyt2US_SSBM&NR=1good

We would recommend that you first DAMP down the substrate with a sponge

and water. Comb out the adhesive with the serrated edge of the trowel, then

back butter the tiles one at a time. Lay immediately into the mortar bed on the

substrate. When using the back buttering method the thin-bed mortar should

be applied uniformly to the back of the ceramic lining material. The tile must

be placed in position with a twisting and pressing motion to ensure 100%

contact with adhesive. Sheets of mosaic should be batted into the adhesive

bed. All joints should be cleaned of squeeze out and sponged clean on

completion of tiling

GROUTING

The minimum period between completion of the tile fixing and commencement

of grouting is three days, where cementacious adhesives are being used.

It is also NOT good practice to grout finished work in small patches.

The use of epoxies or rapid hardening cementacious adhesives MAY allow a

reduction of this period.

POOL TANK FILLING OF H/2O (WATER)The completed installation should stand empty for a minimum period of three

weeks before filling commences providing that all criteria for curing sealants

have been met.

Pool filling should be undertaken slowly in order to minimize

stresses arising from loading and THERMAL CHANGES

arising from the impact of mains water

http://www.youtube.com/watch?v=sr0yMWdWie0 as

explained here,

THE RATE OF FILLING should be carefully controlled toensure the water level rises at no more than 75 cm in every


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24 hours

TEMPERATURE RISE

Similarly stresses arising from initial heating should be restricted to 0.25

degrees centigrade per hour.

All the above information has been recommended bywww.diamopndpoolfinishers.co.uk We will be writing further papers on

swimming pool practice to help educate people interested in building their own

pools or maintaining them and to help professionals understand this industry

in a better context

FOOTNOTE

This short paper is aimed at filling the considerable gap which exists in the

literature on the techniques of modern swimming pool rendering & tiling or as

the trade call it (POOL FINISHING).

DAVID COULSON has been Senior lecturer in Plastering & tiling, andis currently CEO ofwww.diamondpoolfinishers.co.uk

MR COULSON is also available for technical inspections, witness reports,

diagnosis & solutions for swimming pools and can be contacted through the

above web-site Details

DIAMOND POOL FINISHERS also provide the best pool finishing service to

individuals, the swimming pool trade, builders, & local authorities throughout

the UK and can be contacted anytime through

www.diamondpoolfinishers.co.uk


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www.diamondpoolfinishers.co.uk web-sitehttp://www.youtube.com/user/MrGooner59

?blend=6&ob=5 you tube channel .


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Documents

A PAPER WRITTEN TO ASSIST THOSE WHO MAY BE CONCERNED IN THE FINISHING OF CONCRETE SWIMMING POOL’S