Tiled Swimming Pools and Why everyone loves them
They look the Best!
The only reason nowadays why anyone would choose to install
a tiled pool is that they look the Best and are
the Dogs Bollocks of the pools business
There is simply no doubt that from an aesthetic point of
view nothing compares with a beautifully built ceramic tiled pool.
Mosaic
tiled pools never ever seem to quite cut the mustard in this respect
But 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 the technology
with Vinyl Liner Pool Technology.
In the UK things are different because there are firms that
specialise in sprayed concrete that can be used to successfully build water
tight tiled swimming pools using a modern process called Shotcrete.
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, ground pressure 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.
Across the globe such structures
are often 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 and is in common usage in Australia and the US. 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.
In SW France the Ground Conditions are too poor for Gunite
In SW France the ground conditions
are often too poor at pool sites to use Gunite and so conventional reinforced
concrete construction would be required. This involves the construction
of a heavily reinforced slab base (250 to 300 mm thick) and walls (180
to 200 mm thick).
In either case 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
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 main drain 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 - except as we established
above - they look the Dogs Bollocks!
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 (2000 to 4000 euros) and easily on a DIY basis
- Allow leaks to be easily located
and repaired (this will be the subject of a future article)
- 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 cost
half of what ceramic tiled pools 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.
Ceramic tiled pools are based on 40 year old technology and rely on modern
chemical additives to work- but they still look better
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