Timely reminder for renovating prefab pools

It is extremely important when renovating or restoring prefabricated pools that the vinyl liner waterproofing be replaced with another vinyl liner or PVC membrane, and not an alternative rigid surface finish.

Many prefabricated pools constructed in the 1970s through to mid-2000s are now due for refurbishment, so this is a timely reminder of what to consider to ensure the pool remains waterproof.

The most common style of prefab pool was constructed with steel fibre-reinforced concrete wall panels. These pools were constructed with pre-cast concrete coping sections around the perimeter secured using a tensioned, galvanised cable.

If during renovation of the pool, it is found that the tension cable has corroded, this can cause the integrity of the structure to fail. It may be possible, with some difficulty, to replace the cable. If the pool builder is unable to replace the cable, they should consult with an engineer for advice on an alternative solution.

There are other styles of this pool system which use a poured, steel-reinforced concrete coping to lock the panels at the top of the pool.

Waterproofing of all pre-fab pools is intended to be by a vinyl liner only, regardless of the style of pool. The reason being is that these pool systems were engineered to move and absorb ground movement in areas with volatile soil, and rely on the flexible vinyl internal membrane to keep the structure waterproof.

The walls should not be painted, rendered or plastered with fibreglass, pebblecrete or other cementitous plaster, as these finishes lack the flexibility required by the wall joins. In time, vertical cracks may appear where the original wall panels meet, and such cracks usually leak. These cracks can sometimes occur in  a matter of weeks.

Some pools may be able to take a fibreglass surface, but this the exception rather than the rule, and problems will occur if there is any moisture in the pool wall. Moisture affects the long-term adhesion of the fibreglass and, within a few years, the fibreglass surface may fall off.

Another variation on a prefab pool features fibreglass walls and a concrete floor. While a pool with fibreglass walls can be resurfaced with fibreglass or render, it is frequently with short-lived results. This is because there is no chemical bond between the concrete and fibreglass, so there is a risk of leakage at the joins.

A vinyl liner will generally give a far more successful result than other alternatives.