Most home owners never read a waterproofing standard, and nobody expects you to. But when a shower leaks into the room next door, or a balcony stains the ceiling below, the standards are what decide whether the work was done properly. Knowing which ones apply, and roughly what they require, turns a vague complaint into a specific one.
Why the standards matter to you
In Queensland, building work has to comply with the National Construction Code (NCC). The NCC does not spell out how to waterproof a bathroom itself; it points to Australian Standards as the accepted way of meeting its requirements. So when a waterproofing job is assessed, the question is usually "does this comply with the standard the code references?" That is the yardstick a builder, a certifier, the QBCC and an expert witness all use.
AS 3740: wet areas inside the home
The details most often missed are at the edges: the membrane stopping short at a shower hob or door, an untreated junction where wall meets floor, or a floor with no fall so water pools against a wall. None of these are visible once the tiles are on, which is why a leak can appear months or years after handover.
AS 4654: balconies, roofs and anything outside
External membranes work harder than internal ones. They sit in sun and heat, take foot traffic and furniture, and have to cope with water arriving faster than a shower ever delivers. The standard is correspondingly stricter about falls and drainage, which is exactly where balcony leaks tend to begin.
The National Construction Code
QBCC: the time limits that catch people out
The Queensland Building and Construction Commission (QBCC) is where a home owner complains about defective work by a licensed contractor. It separates defects into structural and non-structural categories, and the window to complain is very different for each. Structural defects can generally be raised for years after completion; non-structural defects, which is where a lot of waterproofing sits, have a window measured in months.
What this means when something leaks
- Find your building approval date. It fixes which edition of each standard applies.
- Note when you first noticed the problem, with photos. Dates drive every time limit.
- Ask the builder or waterproofer which standard their work was done to, and for the waterproofing certificate if one was issued.
- If the answer is unclear or disputed, an independent investigation gives you findings measured against the right standard rather than an opinion.
HydroIQ investigates and reports; we do not carry out repairs. When findings are needed to convince a builder, an insurer or a tribunal, that independence is the point. For the rectification itself, our sister company S&S Remedial handles the works.
Common questions
General information for South East Queensland home owners, not advice about your building or a legal matter. Standards and time limits change; check the current edition or rule before relying on a figure here.