Waterproofing defects in Western Australian residential builds

What it is

Waterproofing defects in Western Australian residential building cover any failure of the membrane to keep water out of the dwelling. WA runs a different framework from the eastern states. The Home Building Contracts Act 1991 regulates the contract. The Building Services (Complaint Resolution and Administration) Act 2011 sets up the complaint pathway through the Building Commissioner. The Home Building Contracts Act 1991 also requires Home Indemnity Insurance on most contracts above the prescribed threshold.

Standard of workmanship period

A complaint about the standard of workmanship on home building work can be lodged with the Building Commissioner within 6 years after completion of the works. This is the operative limitation for waterproofing claims in Western Australia. The Building Commissioner can make a building remedy order requiring the builder to fix the work.

The Home Building Contracts Act 1991 also gives a 4 month notification period after practical completion in which the owner can give written notice of defects. The 6-year complaint window with the Building Commissioner runs in parallel and is independent of that contract notification.

Home Indemnity Insurance

Home Indemnity Insurance applies to contracts above the prescribed threshold. It responds where the builder has died disappeared become insolvent or had a licence cancelled. Cover extends up to 6 years from practical completion. Limits are the deposit (up to $40,000) or completion and rectification (up to $200,000).

A waterproofing rectification claim is one of the most frequent claim categories. Insurers price the WA premium against the registered builder's claim history.

Where WA defects most often appear

Building Commissioner complaint patterns and case decisions show the recurring failure modes:

• Wet area floor falls below the 1:80 minimum to the drain.
• Membrane upstands too short or stopped below the finished tile level.
• Penetrations not sealed with a compatible flange or collar.
• No bond breaker at internal corners so the membrane has split.
• Tile bedding laid over a green or contaminated membrane.
• Tiled balconies without a fall to drain or with the membrane not turned up at the threshold.

AS 3740-2021 is the deemed to satisfy reference standard through NCC Volume Two Part H4D2 in Western Australia. The Building Act 2011 makes NCC compliance enforceable through the building permit and inspection regime administered by the local government building surveyor.

Where liability sits

The registered builder holds the contract liability under the Home Building Contracts Act 1991. Subcontracting waterproofing does not pass that exposure on. The Building Services Board has disciplinary jurisdiction over registered building service providers under the Building Services (Registration) Act 2011. Failure to follow a building remedy order can be grounds for disciplinary action.

A waterproofer must hold the relevant building service contractor registration where the work value triggers it. Engaging an unregistered subcontractor is a separate breach.

What an auditor looks for

A TradeLens audit on a Western Australian project checks for:

• Builder registration current for the class of work.
• Waterproofer registration where the work value requires it.
• Home Indemnity Insurance certificate on file before commencement above threshold.
• Membrane product data sheet matched to substrate and exposure.
• Hold point sign-off after membrane and before tile bedding.
• Photo records of upstands hobs and penetrations.
• Flood test record where the wet area requires one.

Each missing item is exposure that can surface in a complaint to the Building Commissioner inside the 6-year window.