Do You Need Waterproofing Under Bathroom Tiles in Victoria?
Do You Really Need Waterproofing Under Bathroom Tiles?
The short answer is yes—you absolutely need waterproofing under bathroom tiles. Tiles and grout are not fully waterproof. Without a proper waterproofing system, water can seep into the structure of your home, causing mould, rot, and expensive repairs.
In Australia, bathroom waterproofing isn’t just recommended—it’s a legal requirement under the National Construction Code (NCC) and Australian Standard AS 3740-2021.
Why Bathroom Tiles Alone Are Not Waterproof
Many homeowners believe bathroom tiles are enough to stop water. The truth is, tiles and grout are only water-resistant, not waterproof. Over time, small cracks, grout gaps, or porous surfaces allow water to penetrate the substrate beneath.
Without proper waterproofing, you risk:
- Water damage to timber, concrete, or plaster.
- Mould and mildew growth, which can affect health.
- Loose or cracked tiles from moisture expanding and contracting underneath.
Waterproofing Requirements in Australian Bathrooms
To comply with Australian waterproofing standards, the following areas must be protected:
- Shower floors and walls – waterproofed up to at least 1.8 metres.
- Bathroom floors – especially when built on timber, plywood, or particleboard.
- Splash zones – around baths, vanities, and sinks.
- Corners and joints – where walls meet floors, and around drains or pipes.
These requirements ensure long-term durability and prevent hidden leaks.
How Bathroom Waterproofing Works
Professional waterproofing under tiles involves several key steps:
- Preparing the surface – cleaning, drying, and repairing the substrate.
- Priming the area – to help the waterproofing membrane bond properly.
- Applying the membrane – usually a liquid waterproofing system applied in multiple coats.
- Sealing corners and joints – with waterproof tape or bond breakers.
- Inspection and certification – ensuring the work meets Australian Standards before tiling begins.
FAQs About Bathroom Waterproofing in Australia
❓ Are bathroom tiles waterproof?
No, tiles and grout are not fully waterproof. They are water-resistant but still allow moisture to pass through over time. This is why a waterproofing membrane under the tiles is essential.
❓ Is waterproofing required by law in Australia?
Yes. Under the NCC and AS 3740-2021, all wet areas such as bathrooms, showers, and laundries must be waterproofed by a licensed professional.
❓ How much does bathroom waterproofing cost in Australia?
The cost of waterproofing a bathroom in Australia typically ranges from $500 to $1,000+, depending on the size of the bathroom, the condition of the substrate, and the complexity of the job.
❓ Can I waterproof my own bathroom?
DIY kits exist, but in most states and territories, waterproofing must be done by a licensed waterproofer to comply with building regulations.
❓ How long does bathroom waterproofing last?
When done professionally with high-quality materials, bathroom waterproofing can last 10–15 years or more. Regular maintenance of tiles and grout will help extend its lifespan.
DIY vs Professional Waterproofing Under Tiles
While some DIY kits are available, Australian law requires waterproofing in bathrooms to be done by a licensed waterproofer. A certified professional ensures the membrane is applied correctly and provides documentation for compliance.
Skipping professional waterproofing may seem cheaper at first but can lead to thousands of dollars in repairs if leaks or mould appear later.
Key Takeaway: Always Waterproof Under Bathroom Tiles
So, do you need waterproofing under bathroom tiles? Yes—every bathroom in Australia must be waterproofed to meet building codes and protect your home.
By hiring licensed waterproofing experts and using high-quality materials, you’ll protect your bathroom from leaks, mould, and structural damage—keeping your home safe and your renovation investment secure.