Bathroom Waterproofing in Unley

Pre-1980 bathrooms often have a "thick bed" installation — tiles set in a deep mortar screed rather than modern tile adhesive. These installations can be structurally sound for many decades, but when they do fail, the mortar bed usually needs to come out entirely to expose the substrate and apply a proper membrane system. This is more work than stripping a modern adhesive installation, and we'll factor this into our assessment and quote.

Yes, unfortunately. If water has been tracking through the floor of a bathroom lean-to into original timber framing, it can cause structural damage that compromises heritage fabric that should be retained. This is why we always assess the extent of any moisture damage when the tiles come off, and advise on any structural repair needed before we apply new waterproofing. In some cases, we involve a structural engineer in the assessment for complex situations.

Common signs include: water stains appearing on the wall or ceiling of the room below your bathroom; damp patches on walls adjacent to the shower; mould growth that keeps coming back despite cleaning; tiles that have come loose or grout that is cracking and falling out; a musty smell in or around the bathroom. If you notice any of these, don't delay — waterproofing failures get progressively more damaging and expensive the longer they are ignored.

Rarely. If the waterproofing membrane has failed, the tiles must come off to expose and repair the membrane. Some very early-stage grout failures can be addressed with penetrating sealers, but these are temporary measures, not permanent repairs. If water has penetrated to the substrate, no topical treatment will fix the problem — the tiles need to come off and the work needs to be done properly.

AS 3740 is the Australian Standard for waterproofing of domestic wet areas. It specifies exactly where membranes must be applied, to what heights, in how many coats, and what testing is required. All builders and waterproofers in Australia are required to comply with this standard. When we waterproof your bathroom, we comply fully with AS 3740 and can provide documentation confirming this — important if you ever sell your home or make an insurance claim.

A properly applied membrane system should last the life of the tiles — typically 20–30 years or more. The grout joints should be inspected and resealed every 5–7 years as part of normal maintenance. Failures are almost always caused by inadequate application (skipping coats, insufficient height on walls, or poor preparation) rather than the membrane materials themselves. This is why we never cut corners on waterproofing application.

Waterproofing scope varies significantly depending on the size of the wet area, the extent of substrate repair required, and whether this is a standalone waterproofing repair or part of a full renovation. We don't publish pricing online because every situation is different. Contact us for a written quote after we've assessed the specific situation — it's the only way to give you an honest number.

Technically, homeowners can apply waterproofing products themselves in South Australia. However, if the waterproofing is done incorrectly and subsequently fails — causing damage to the structure — home insurance claims may be affected if the work wasn't done to AS 3740 by a competent person. Licensed builders who apply waterproofing must do so to the standard and can certify their work. Given waterproofing is the most consequential layer in a bathroom, this is one area where we'd strongly recommend using a qualified tradesperson.