Tiled Swimming Pools and Why Most people prefer them
They look the Best!
From an aesthetic point of view nothing compares with a beautifully built, traditional, freeboard (see Deck Level pools below) large tile pool.
Mosaic tiled pools never ever seem to quite cut the mustard in this respect but have the advantge that the tiles are supplied in sheets and are much easier to install than large tiles. In fact it is very difficult to find any tradesmen that are both willing and capable of producing a first class large tiled pool.
Deck Level Pools
In a freeboard pool the water level lies about 150mm below the pool copings and this 150mm is exposed to view and the tiling can be clearly seen.
In a deck level pool that water laps over the coping and spills through a grill into a gutter and in this case the pool wall and any tiling is covered by water and cannot be seen and any aesthetic advantage of tiling is negligible.
Why do Tiled Pools so often leak?
The question posed above can be answered with the simple statement "Most tiled pools leak because of faulty design and installation procedures"
Let's take look at what is required in ensuring that a tiled pool does not leak and then compare this with vinyl liner installation.
The Design and Construction of tiled pools
Tiles can only be placed on walls and floors that are structurally rigid and that do not flex under water pressure, differential settlement or temperature change. If flexing occurs the tiles will come off. The tiles themselves are not water-proof and so the structure itself has to provide the water-proofing.
In the US and Austalia such structures are commonly formed with Gunite that involves projecting concrete pneumatically at high speed onto a natural ground surface or onto a formed surface using shuttering. Reinforcement consisting of steel wires or rods is put in place before so that the gunite surrounds them and becomes "reinforced concrete". The method of construction allows both curved and flat shapes to be formed. It does require good ground conditions because it is impractical to build thick sections using this technology.
Gunite is a process that uses quite dry concrete and is now being replaced by Shotcrete where wet concrete is pumped onto similar formwork under high presssure.
When the Ground Conditions are too poor for Gunite
The ground conditions at a pool site can be so poor (Running sand and waterlogged ground) that conventional reinforced concrete construction is required. This involves the construction of a heavily reinforced slab base (200 to 300 mm thick) and walls (180 to 200 mm thick).
The structure must be designed by an experienced fully qualified civil / structural engineer who will take all the ground conditions, pool size, pool depth etc into account.
The most important construction issue relates to the joint between the heavy ground slab and the walls. The slab obviously has to be cast first. The shutters for the walls are then erected and the walls concrete poured a day or so later. This results in a joint that is virtually impossible to water-proof in a 200 mm thick wall.
Hence the water-proofing is
provided by a water-proof membrane that is applied to the surface of
the very expensive pool structure. The quality of the membrane and the
leakiness of the pool relies entirely on the materials used, the mix
proportions, the mixing and the skill and integrity of the plasterer.
Other ceramic tiled pool construction issues
There are various other construction issues that need to be taken into account in the design and installation of a ceramic tiled pool and these include:
1.) The concrete base slab and
the walls will need to be cleaned by water blasting, shot blasting, grit
blasting etc to ensure that the render / screed sticks on - these are
all very dirty processes that take a lot of time to undertake
2.) The concrete base slab and the walls will need to be levelled with
render / screed to get the necessary flatness for tile installation (< 3mm
in 3m) - this may also need cleaning before the membrane is applied
3. ) After leveling the waterproof membrane will need to be applied -
this will be a proprietary latex based product mixed with Portland cement
that will stop moisture penetration, moisture expansion, chemical attack
by chlorides and efflorescence. The membrane will need to cure for 7 days
at 20 + degrees C.
4.) After curing the pool will need to be flood tested for leaks - this
will involve filling at a slow rate of 600 mm in 24 hours. Fugitive dyes
and a scuba diver will be required to locate any leaks
5. ) Mosaic tiles will need to be paper faced ceramics as back mounted
mosaics can come off the wall following saturation and pool water chemical
attack
6. ) Tiles must be impervious or vitreous to reduce the effects of moisture
expansion and to eliminate freeze / thaw problems
7. )The tile mortar bed must be latex based to reduce chemical attack and
improve flexibility to withstand moisture expansion and shrinkage or epoxy
based (expensive and can be difficult to use)
8. ) The grout can be latex based or epoxy based - epoxies can discolour
under sunlight.
9. ) Movement joints must be provided in the tiling in strict accordance
with the grout manufacturer's installation instructions
10. ) The latex based beds and grouts will need to cure for 14 days at
20 degees C (10 days for epoxies)
11. ) Pool to be filled at 600 mm per 24 hours to prevent excessive water
pressure, thermal and moisture differentials. Filling should not proceed
in direct hot sunlight or with very cold water
12.) The various chemicals and the tiles themselves are provided by several different manufacturers and used by different tradesmen. As a result an overall guarantee of the complete system is never available and many pool buyers have found themselves paying for retiling when it is required.
Through the wall pool equipment and main drain items in PVC are not compatible with the surrounding concrete
There is another major potential problem with tiled pools that relates to the "through the wall equipment" and the main drain. These items are made in high quality PVC that is not suceptible to corrosion from the chlorinated water in the pool. But whilst the plastic is excellent from a corrosion point of view the concrete that is cast around the plastic inserts like the skimmers and main drain etc tends to shrink away from it and it is virtually impossible to stop leaks occuring, particularly around the floor outlets where the water head is highest.
In a liner pool mechanical joints
with high quality gaskets are installed - these virtually never leak
and if they do because of faulty installation - the joint is easy to
repair.
So It is no wonder that tiled pools take so long to build and are so susceptible
to leakage!!
Ceramic tiled pool operational issues
The control of pool water chemistry is very important in ceramic tiled pools:
1. Chlorine uses and depletes
calcium and so calcium balance is essential to prevent deterioration
of cement based grouts and mortars
2. If the pH is too high mineral deposits will form on the tiles and grout
- they can form under the surface of the ceramic tiles causing the surface
to come off the tiles
3. If the pH is too low acidic etching of the grouts and mortars can occur
4. If the calcium hardness is too low the pool water will etch calcium
from the grout and if it is too high calcium deposits can form on any of
the pool surfaces
5. At normal pH values iron and copper metals will come out of solution
and can then be deposited as stain on tiles, grout and pool fittings
Another common problem is that the skimmers become loose in the concrete wall in which they are built. This results in leakage that can only be cured with putty that is unsightly and likely to be picked out by small fingers!
PVC liner pool technology is more cost effective
When everything is taken into consideration it is difficult to understand why anyone would want to take the risk of building a ceramic tiled pool.
PVC liner pools:
- Will not leak even under quite large structural movements in the pool walls and floor
- Vinyl liners can be renewed comparatively cheaply and easily on a DIY basis
- Allow leaks to be easily located and repaired
- Are virtually impervious to chemical attack (calcium deposition can occur but PVC is much easier to clean than tiling and grout)
- And last but not least they look good - but not as good as a ceramic tiled pools!
Tiled ot vinyl liner?
PVC liner pools will cost a lot less than what a ceramic tiled pool will cost and are superior in just about every way. They are based on the latest material technology and are environmentally friendly because of the reduced requirement for energy intensive cement and steel products.
BUT
Bluepools has recently undertaken several projects where tiles have been used on a Polyblok wall. This exciting new technology is now available in the UK.