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# Bathroom waterproofing, done to the Standard.

The membrane beneath your bathroom tiles is the only thing standing between water and the structure of your home. We install compliant wet-area waterproofing to AS 3740 — certified, warranted and done once, correctly.

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Residential

## Your tiles are not waterproof. The membrane beneath them is.

It is one of the most common and expensive misunderstandings in home renovation: the belief that a tiled, grouted, sealed bathroom is waterproof. It is not. Grout is porous, silicone perishes, and water passes through tiled surfaces continuously. The only thing keeping that water out of your walls, floors and the rooms below is the waterproofing membrane hidden beneath the tiles.

When that membrane is missing, under-specified or poorly detailed, water enters the substrate. The damage is slow and invisible at first — then it appears as a stained ceiling below, hollow tiles, a musty smell or a rotting wall frame. By then the repair means stripping the bathroom back to structure.

In Queensland, bathroom waterproofing is a regulated activity. It must be installed to AS 3740 by a QBCC-licensed waterproofer and certified with a written inspection certificate before tiling. We do exactly that — and document it so you have the evidence.

What we waterproof

## Every wet area, detailed correctly

### Shower recesses

Fully-tanked shower areas with correct falls to waste, reinforced hobs and puddle flanges — the highest-risk zone in any bathroom.

### Bathroom floors

Full-floor membranes where required by the Standard, with reinforced floor-to-wall junctions and correctly detailed wastes.

### Walls & wet walls

Membrane to wall areas within and adjacent to showers and baths, to the heights required under AS 3740.

### Ensuites & powder rooms

Compliant waterproofing for ensuites, powder rooms and WCs as part of new builds and renovations.

### Renovation re-waterproofing

Stripping failed original membranes and re-waterproofing during bathroom renovations, back to bare substrate.

### Inspection certificates

Written AS 3740 inspection certificates issued before tiling — documentation for certifiers, insurers and resale.

The AS 3740 process

## How a compliant bathroom is waterproofed

#### Substrate check & preparation

We confirm the substrate is sound, dry and correctly fell to waste, then prime. Falls and waste positions are critical — getting them wrong at this stage guarantees future problems.

#### Detailing & reinforcement

Bond breakers at movement junctions, reinforcing fabric to all internal corners and floor-to-wall junctions, and puddle flanges bedded at wastes.

#### Membrane application

The specified membrane applied in the correct number of coats to achieve the required dry-film thickness, to walls at the heights AS 3740 prescribes.

#### Inspection & certification

The cured membrane is inspected and a written AS 3740 inspection certificate issued — before your tiler begins.

AS 3740 essentials

## What the Standard actually requires

AS 3740 is detailed and technical. These are the essentials every homeowner and renovator should understand about compliant wet-area waterproofing.

- Shower areas fully waterproofed — floors and walls to prescribed heights, with the whole enclosure treated as a wet area.
- Correct falls to waste — the floor must drain to the waste with no ponding; falls are set before waterproofing.
- Reinforced junctions — all internal corners and floor-to-wall junctions reinforced with bond breaker and fabric.
- Compatible, compliant materials — membranes suitable for wet-area use and compatible with the substrate and adhesives.
- Licensed installation — carried out by a QBCC-licensed waterproofer in Queensland.
- Inspection before tiling — the membrane inspected and certified before tiles are laid over it.

Common questions

## Bathroom Waterproofing FAQs

Only if the existing membrane is sound, compliant and can be inspected and certified — which is rarely the case with older bathrooms. Tiling over an unknown or failed membrane without inspection is non-compliant and risks the same failure recurring. In most renovations we recommend removing the old membrane and re-waterproofing to current standard.

It depends on the bathroom design and the requirements of AS 3740 for that layout. Shower areas are always fully waterproofed. Whether the entire floor requires membrane depends on factors such as the floor construction and whether the room is enclosed. We assess this against the Standard for your specific bathroom.

Once the final coat has cured — typically 24 to 48 hours under Queensland conditions, longer in cool or humid weather. Tiling before the membrane has fully cured can cause adhesion failure, so we confirm cure before handing over to the tiler.

Yes. We provide a written AS 3740 inspection certificate confirming the waterproofing was installed and inspected to standard. Keep this with your renovation documents — it is valuable at resale and for insurance.

Related services

## Explore related work

Residential Waterproofing
Balcony & Terrace Waterproofing
Remedial Waterproofing
Waterproofing Inspections
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## Waterproof your bathroom once, correctly

Renovating or building? Book a free assessment for a compliant, certified and warranted bathroom waterproofing installation.

Request an assessment
Call 0488 773 232