Waterproofing Certificates: What They Are and Why You Need One
A waterproofing certificate is the document saying the wet area was done to standard, by a licensed contractor, using a specified system.
It’s a small piece of paper that matters far more than people expect – at handover, at sale, and in any dispute afterwards.
What it records
- The address and the specific areas waterproofed
- The contractor and their licence number
- The system and products used
- Confirmation the work was carried out to AS 3740 and the National Construction Code
- The date
In short: who did it, what they used, and to what standard.
Why builders want it
Certifiers ask for it. Without documentation covering the wet areas, occupation gets held up – and a build that can’t be occupied is a build that isn’t finished.
It also transfers accountability to where it belongs. If a bathroom leaks in three years, the certificate identifies who waterproofed it and what they used. That’s protection for the builder, not just a document for the file.
Why homeowners should keep it
Two reasons, and both arrive years later.
Selling. A buyer’s inspector asking about a renovated bathroom is much easier to satisfy with a certificate than without one. No certificate invites the question of whether it was done properly at all.
If it fails. The certificate tells you who to go back to. Without it, you’re trying to establish who worked on a bathroom several years ago, and you’ll usually end up paying for the repair yourself.
If your contractor doesn’t offer one
Ask why. In NSW, waterproofing is licensed work. A licensed contractor issuing a certificate is normal practice, not a favour.
Someone unwilling or unable to provide one is telling you something about how the job is being done, or about who’s actually doing it.
Ask for the licence number too, and check it. It takes a minute and it’s a reasonable thing to do before letting someone waterproof your bathroom.
Need someone to look at it?
We inspect before we quote, across Sydney. Call 0450 679 512 or email sam@sydneychoicewaterproofing.com.au.
NSW Contractor Licence 299661C · Fully insured · 7 year warranty