Precast swimming pool shell in Kuźnik

A pool cast in situ is one of the most labour-intensive structures in single-family building. Formwork of varying geometry has to be assembled, reinforcement fixed, the walls and the floor concreted without interruption — because every break in concreting is a potential leak — and then the concrete has to cure and the surface be levelled before the tanking goes on.

In a precast unit all those stages happen in the plant, on a casting bed where the geometry is controlled by the mould and the curing conditions are the same whatever the weather. What arrives on the plot is a finished unit. The work on site comes down to preparing the ground, setting the shell and making the connections.

The floor matters most of all. The falls — towards the outlet, and at the transition between the shallow and the deep end — are worked by hand in traditional construction, floating the concrete to the angle, and their accuracy is what the pool plant has to live with afterwards. Here the angles are set by the mould, so the floor arrives in its final shape.

The same goes for the surface. A wall cast in a mould comes out smooth and true over its whole face, with no wet floating down in the excavation. It is a surface that takes the finishing layers straight away.

Precasting a pool shell also shows that the technology is not confined to the walls and floors of a building. A unit of unusual geometry is made in the same way as a standard one — the difference is in the mould, not in the process — and the more labour-intensive the structure would be on site, the more there is to gain by moving it into the plant.

The landscaping, the pool services and the finishes stayed with the client.

Scope of work: precast concrete pool shell with the falls of the floor formed in and a surface finished off the mould, transport and erection on site.