At a Glance
You are renovating a 1990s bathroom and the tiler has told you the waterproofing needs to be redone before new tiles go on. That is a standard situation in Brisbane, and it costs $550–$3,150 per bathroom. The range is driven by bathroom size, floor type, and whether any existing water damage needs to be repaired first. Brisbane's concrete slab construction keeps most jobs toward the lower half of the range.
What's Included in the Price
- Surface preparation: grinding, cleaning, and priming the concrete or prepared substrate
- Membrane application across all wet areas as defined by AS 3740 Waterproofing of Domestic Wet Areas
- Treatment of all penetrations: floor waste, shower drain, tap entries, and shower niches
- Bond breakers and puddle flanges at junctions and drain points
- QBCC compliance certificate on completion
- Pre-tiling inspection coordination
In Brisbane, most homes sit on concrete slabs, which means less preparation than timber-framed floors. This keeps the preparation component of the cost lower than in southern capitals where timber subfloors are common.
What Affects the Cost
- Bathroom size. A 3 to 4 square metre ensuite costs significantly less than a 10 square metre family bathroom or full wet room.
- Renovation vs new build. Renovation adds demolition, old membrane removal, and substrate repair.
- Floor type. Concrete slabs are standard in Brisbane and straightforward to waterproof. Older high-set Queenslanders with timber floors require overlay before membrane application.
- Shower type. Hobless walk-in showers are popular in Brisbane renovations but need more precise falls and broader membrane coverage.
- Humidity damage. Brisbane's subtropical humidity means waterproofing failures show up fast as mould and staining. If the old membrane has failed, there may be moisture-related damage to address before new waterproofing.
- Number of penetrations. More drains, taps, and niches mean more individual waterproofing treatment.
A standard bathroom on a concrete slab in a post-2000 home in Springfield or North Lakes, with a shower hob and minimal penetrations, sits toward $550. A large bathroom renovation in an older Queenslander in Paddington or Red Hill with timber floors, subfloor preparation, a hobless shower, and multiple niches pushes toward $3,150.
Brisbane-Specific Considerations
Brisbane's housing stock divides into two main categories for waterproofing purposes: concrete slab homes (the majority of post-1970s construction) and high-set Queenslanders with timber floors.
Slab-on-ground homes across suburbs like Sunnybank, Eight Mile Plains, and the newer estates of Springfield and North Lakes offer the most straightforward waterproofing. The concrete substrate is stable and well-suited to liquid-applied membranes without additional preparation.
Queenslanders and older high-set homes in Paddington, Red Hill, Ashgrove, and Woolloongabba present a different situation. Timber-framed bathroom floors flex under load, and the membrane system must accommodate that movement. A compressed fibre cement sheet overlay is laid over the timber before waterproofing begins. These homes also tend to have smaller, less accessible bathrooms that take more time to waterproof properly.
Brisbane's humidity accelerates the visible effects of waterproofing failures. Mould growth, damp patches, and staining appear faster than in drier climates. On a concrete slab, water from a failed membrane tends to travel sideways to adjacent rooms rather than down through the slab, so the damage can appear some distance from the source.
The QBCC (Queensland Building and Construction Commission) requires waterproofing compliance certificates, and the work must be inspected before tiling commences.
Hiring a Licensed Waterproofer in QLD
In Queensland, waterproofers must hold a QBCC licence with the waterproofing trade class. This requires a Certificate III in Construction Waterproofing (CPC31420). You can verify a licence on the QBCC licensee register.
Ask for:
- Current QBCC waterproofing licence number
- Compliance certificate on completion
- Confirmation of pre-tiling inspection
- Public liability insurance
Red flags: No QBCC licence, suggesting that tiling can start the same day as waterproofing (the membrane needs curing time), or claiming that the inspection before tiling is optional. In Queensland, it is not optional. If the membrane is covered without inspection and a problem surfaces later, you have no evidence the work was done correctly.
How We Calculate
Estimates are based on surveyed rates from QBCC-licensed waterproofers in the Brisbane metropolitan area, adjusted for typical construction types in QLD. All prices include GST. Figures cover standard residential bathroom waterproofing and do not include tiling, plumbing, or structural repairs.