The benefits of using waterproofing membranes when constructing swimming pools

The usual material used in swimming pool construction is reinforced concrete with the added benefit of internal or negative side waterproofing.  Consideration to both ingress and egress of water needs to be factored equally when designing an appropriate waterproofing system.

A Waterproofing Designer should consider many factors, such as the grades and dimensions of the concrete structure, is it earth retained on all elevations, what are the intended finished surfaces to be applied over the waterproofing and is it to be exposed to direct UV radiation during its service life.

Another major concern, especially with thinner concrete elevations or sections; is flexing of the pool shell when both filled and emptied.  Frequent filling and emptying maybe required for maintenance, cleaning, replacement of failed tiles, etc.  These flexing/tensile bending events can lead to failure of post applied liquid or render types of waterproofers, with best advice always being to empty and re-fill pools over several days rather than at once to reduce the chances of “shocking” concrete structures and therefore promoting cracking of the substrate itself.

One way of dramatically reducing this particular risk is by specifying a fully bonded, elastomeric type of waterproofing to be directly applied to its substrates, which has an ability to resist cracking, whilst still having the required resistance to both, given head of water and any flexing/crack widths that a structural engineer has designed their concrete structure to.

Using a more rigid render type system will naturally increase risk in this instance, as they are more likely to break away from a structure on flexing and therefore lead to waterproofing failures.

Another high risk area is where penetrations are part of the structure, so careful product selection of waterproofing products and detailing is imperative.  Penetrations can vary, from sleeved services to non sleeved, things like suitible puddle flanges and or hydrophilic strips and waterproof mortars, waterproof mastics, or combinations of such need consideration.

When the inside of pools require tiling, it is often prudent to apply render coats to both protect and enhance the waterproofing, as well as to provide a level and uniform surface to apply tiles to. It is also prudent to use appropriate bonding agents for renders or tiles when applied over a hydrophobic waterproof coating, as they are naturally designed and intended to repel water and moisture.

On many projects and due to the risks associated with failures, cavity drain membranes are considered and typically installed on the inner faces of the concrete box and across the slab with drainage points located beneath the membrane taken to a sump pump often located in a service void adjacent the pool with maintainable access. In this instance an inner box is formed consisting of a loading slab upon the floor membrane often with insulation beneath and an inner block work wall constructed whereupon the inner waterproofing is applied thus forming a drained box.

Delta Membrane Systems have a wide range of products and systems suitable for successful waterproofing of swimming pools.  Our Technical Team will be more than happy to assist with your designs.