Uneven swimming pool due to settlement of the pool shell.
When a swimming pool is built, the work starts from the top so that the horizontal alignment of the mosaic tiles is not affected; for that reason, a square and level line is marked out from the upper centre of the wall to serve as a reference for drawing the horizontal axis.
Tiling then begins at the top of a vertical wall. From there, and perfectly level, the mosaic tile sheets are fixed side by side with tile adhesive. Tiling never starts at the ends of the wall, but from the point where the axes cross at the centre of the wall, at the top.
Once the walls have been tiled, the floor is left until last, where the coving or curved mosaic pieces can be fitted to size; there, any breaks in continuity go unnoticed, as pieces or wedges are cut or trimmed to join the vertical walls to the floor.
When the pool is filled, the water level or waterline shows what is horizontal, and it will line up with the straight horizontal lines of the tiles, because the horizontal alignment started from the top of the pool. Any irregularities or differences in level in the floor are corrected, as explained, with coving, curved pieces or mosaic wedges cut to size.
This construction method is basic and universal. Neither common sense nor anyone else would explain that the horizontal alignment starts or comes from the bottom of the pool, because pool floors, whether for repairs, for draining the water when it is dirty or for renewing it, are always sloped and never horizontal, precisely so that water does not stagnate, with the outlet drain at the deepest point. This applies to communal and private pools alike. It is all pure common sense.
Why do we insist so much on how the mosaic tiles are laid? Because when the pool shell tilts as a result of differential settlement (something quite serious that can end with cracks in the pool), the site manager or architect in charge may be tempted, to distance themselves, to say that the unevenness is merely aesthetic. Or that whichever tiler happened to be on site laid “the tiles already on a slant” (?…).
That is not true. It is not an initial mistake or an aesthetic defect: rather, the pool is no longer level, because of a genuine tilting of the shell, which was originally level but has undergone differential settlement.
Clearly there is damage to the pool (the loss of level) caused by the careless and negligent conduct of the technician or architect who managed the works, who did not bother to examine the ground; later the shell tilted, shifted and lost its level through differential settlement. There may even be hairline cracks or cracks, and the shell may break, because of that tilting, or because of a cavity or severe void in the supporting subsoil, or because a large inflow of groundwater has further altered the bearing capacity of the ground.
So, since we have unfortunately heard the excuse that “the tiles were not laid level to begin with” on many occasions, even from experts or architects giving evidence at trial, if you have been given that clumsy explanation, ignore it: the liability lies with the technician or architect who managed the execution of the works, for failing to examine the pool’s subsoil thoroughly (which was probably not sufficiently compacted), or for the subsoil being unsuited to the characteristics of the pool’s foundations. It is not a mere aesthetic defect.
See the following link to read another article we have published on water loss from swimming pools
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