Renovating your bathroom can be exciting, but when it comes to waterproofing, it’s one area where DIY won’t cut it. Bathroom waterproofing is essential, and only a licensed professional should handle it.
Poor waterproofing can lead to costly issues, from unsightly mould to serious structural damage. So, why risk it? Getting waterproofing right from the start can save you a bundle in the long run.
Waterproofing to the letter of the law
Bathroom waterproofing in Australia is governed by strict standards to protect your home. The Building Code of Australia (BCA) and Australian Standard AS3740 outline the necessary requirements for waterproofing in wet areas like bathrooms. Here’s what’s generally required:
- Floors within shower enclosures must be fully waterproofed.
- Shower walls should be waterproofed to a height of 1800mm.
- Bathroom walls need a waterproof layer up to 150mm.
- Timber floors or bathrooms on upper levels must be fully waterproofed.
- The step-down from the shower should have waterproofing applied up to 100mm.
What is the process?
Before you get to tiling, the waterproofing is completed by either your renovator or a dedicated waterproofer, who applies a waterproof layer beneath the surface. Typically, waterproofing takes around two to three days and follows these steps:
- Preparation: First, the area is cleaned and primed. Joints, floor penetrations, and wall-to-floor junctions are sealed with silicone.
- Application: A coat of waterproof membrane is painted on and left to dry overnight.
- Second Layer and Inspection: The following day, a second layer is applied, which is also left to dry.
- Testing: After another 24 hours, the area can be tested and inspected to ensure the seal is effective.
The waterproofing must dry completely before additional work continues, so plan to pause your renovation for a couple of days if necessary.
What happens if waterproofing fails?
Remember, even a tiny tear in the membrane could leave your home looking like this even years down the track:
In this case, Perth building inspector Russel was called in to assess some shoddy waterproofing on a first-floor shower which led to the waterproofing membrane breaking down over seven years later – causing severe damage to the structure below and requiring an entire bathroom reno.
And to make matters worse, the extended time frame and classic ‘cowboy’ tradie business practices meant the homeowner was stuck footing the repair bill as both the builder and insurer tried to dodge responsibility.
What to know before hiring a waterproofer
In New South Wales and Queensland, anyone who waterproofs must hold a waterproofer’s license. This licensing ensures that your waterproofer has the right training (typically, a Certificate III in Construction Waterproofing) and knows how to properly seal a bathroom.
Even in areas where licensing isn’t required, always request a compliance certificate and warranty on the job, so you know it’s done to industry standards. Tilers may sometimes be licensed to perform waterproofing too, so check their qualifications if they’re handling both jobs.
Questions to ask your tradie
When you’re ready to hire a waterproofer, here’s what you should ask to make sure they’re the right fit:
- Are you licensed and insured?
- How long will the job take?
- Can you give me a written quote?
- Do you have customer references I can check?
- What type of warranty comes with your waterproofing?
And here’s a tip: always get at least three quotes before making a decision, so you can compare prices and service offerings.
How much does it cost?
Waterproofing costs vary, but expect to pay around $500 to $750 for a standard-sized bathroom. At the lower end, you might find quotes as low as $40 per square meter, but large or complex bathrooms may cost more.
If you’re waterproofing multiple bathrooms or doing it as part of a full renovation, you might snag a discount.
Comparing quotes from local providers is the best way to gauge your budget and find the right fit. While price matters, reputation counts too—don’t compromise on quality when it comes to waterproofing, as a leaky bathroom can end up being much more costly in the long run.
