Who certifies waterproofing, and do I need a certificate?

Waterproofing is one of the few parts of a build that is meant to come with paperwork, and it is one of the parts most often handed over without any. The certificate is not red tape. It is the proof the wet area was done to the Standard and tested before it was tiled over. Here is who issues it and when you need it.

Who can issue the certificate

In Queensland, waterproofing of wet areas is a licensed trade, and a licensed waterproofer is the one able to certify the work they install. The certificate says the membrane was built to AS 3740 inside or AS 4654 outside and flood-tested. A handyman who also does waterproofing, or a tiler who waterproofs as an afterthought, is usually not able to give you that, which is the first reason to ask who is actually doing it.

When you need one

• A bathroom or wet-area renovation. Your builder or certifier will want the certificate before the job signs off.
• A new build. The wet areas have to be certified as part of the build approval.
• An insurance claim. If a leak ever causes damage, the certificate is the proof the work was done to the Standard.
• Selling the home. A buyer or their inspector can ask, and a certified wet area is one less thing to argue about.

The certificate is cheap insurance against an expensive argument. The job that cannot be certified is usually the job that was not done to the Standard in the first place.

The test behind the certificate

A certificate is only worth the test behind it. Once the membrane is installed and cured, we plug the wastes and flood the area, then leave it to confirm it holds before any tiling starts. The flood test is the difference between it looks done and it is proven to hold water. We test, we certify, and we hand the paperwork over with the warranty.