Waterproofing Swimming Pools
Waterproofing swimming pool is a critical component of the construction works required when building a pool. Certainly within the swimming pool industry, no specific specialised trades were ever employed to waterproof the structure of the pool. Instead, in-ground pool builders relied on:
- the density and thickness of the concrete pool shell
- the relative impermeability of the surface coatings applied to the concrete pool form
- the epoxy seals and expandable foams to seal around penetrations (pipes, etc).
Most people imagine a pool leak in a swimming pool to be related to the failure of plumbing lines. Although this is sometimes the case, it is uncommon and easily fixed due to:
- the widespread use of pipe pressure testing equipment to check for failed lines
- the use of mini excavators to excavate the pluming lines to fail safe depths.
Pools also leak through “penetration leaks”. Simply, this is when water leaks out of the pool concrete form around the pipe or fitting penetration. Pool builders try to mitigate these type of leaks through applying epoxy collars and swell-able water stops. This works really well when correctly implemented.
The other type of water leak in a swimming pool and by far the hardest to fix is a “structural leak”. In this type of leak, water leaks through the concrete form of the pool shell at a slow and often undetectable rate. Most people aren’t even aware of having a “penetration or structural leak” in their swimming pool. Unless they can visually see a buildup of water on an exposed part of the pool, it is difficult to notice a leak.
Leaks in Older Swimming Pools
Past building practices meant that nearly every swimming pool shell was built in-ground and was fully concealed within the excavation. A penetration or structural leak in an in-ground pool, built as such, would be undetectable. It is integral with modern building styles of elevating pools and building pools within apartments that the pool is waterproof. In these builds, even a small leak will show up in plaster works or the walls of the levels immediately below the pool. Hence, the present need for a specialist trade and methods in waterproofing pools.
We mitigate water loss via swimming pool leaks through the following best practices:
We pressure test pipes and use our own excavator to dig trenches so they are at a safe depth. We also locate our pool plumbing lines near the pool shell and try to limit all services being enclosed in single service trench. Finally, we often back-fill over our plumbing lines with ¼ minus screenings or friable sand.
We fit epoxy collars around all our pipes and penetrations using a thixotropic plural component epoxy. We also use swell-able water stops when needed.
We fit a 2 component polyurethane sprayed membrane. This is a practically indestructible and completely impermeable membrane lining. It is best suited to critical waterproofing applications in apartment buildings, etc. where even a small water loss forms a critical problem.
We don’t fit membranes when a pool is to be built in a traditional fashion, fully encased within an earth excavation. This is because the small water loss of a few litres a day (if at all) is minuscule and not worth the expense of fitting an expensive membrane lining to the pool form.
We often fit very dense 3:1 render mixes with polymer modified render linings to our pool forms. This is part of the tiling process. This creates a near impenetrable barrier to water loss, although small leaks through such cementitious linings are a low possibility.