What are the Waterproofing Rules in Australia? - Owner Builder Club

What are the Waterproofing Rules in Australia?

Can you waterproof your own home

Hmm, what are the waterproofing rules in Australia? Specifically, what is the Australian Standard for waterproofing in residential construction? Well, it isn't just about keeping your feet dry, it's about ensuring the durability and safety of your home. 

And with recent updates to these standards, staying informed has never been more crucial for builders and owner builders alike.

Let’s talk all about waterproofing standards below.

Waterproofing Rules in Australia, the basics

So, what exactly is the Australian standard for waterproofing? Think of it as the rulebook for keeping homes safe and dry. In the world of construction, it's the guideline that ensures water doesn’t go where it shouldn’t, protecting your home from damage and decay.

The importance of these standards cannot be overstated. Water damage can lead to a host of issues, from structural problems to health concerns like mould. 

That's why adhering to these standards isn't just a recommendation, it's a necessity for the longevity and safety of your dwelling.

But here’s the kicker – these standards are not static. They evolve, with recent updates reflecting the latest in waterproofing technology and practices. 

Why does this matter for you, the owner builder? Remember that you're the builder so knowing and understanding the standards is critical and adhering to the standards even more so.

Why It Matters

Let's talk about what's at stake with less-than-ideal waterproofing. First off, there's the structure itself to consider. Just as water seeps through the fabric of your clothes, it can seep into the very bones of your home if not properly shielded.

This can weaken the structure, cause unsightly cracks, or in worst-case scenarios, lead to parts of the home becoming unsafe. Think of it as the architectural equivalent of catching a cold that turns into pneumonia.

But it's not just the building that suffers. Ever walked into a damp room and felt that musty, unwelcoming air? That's often the first sign of moisture where it shouldn't be, potentially leading to mould and mildew. 

These uninvited guests don't just smell bad; they can pose serious health risks, especially for those with allergies or respiratory issues.

This is where the magic of effective waterproofing comes in — it acts like a sturdy, reliable umbrella for your home. Ensuring areas prone to water exposure, like bathrooms and kitchens, are well-protected is non-negotiable. 

It's about using the right materials and techniques to create an invisible barrier that keeps water out, ensuring the safety, integrity, and comfort of your living space.

Dive Into the Details: The Australian Standard

When it comes to keeping the wet areas of your home snug and dry, the National Construction Code 2022 has got your back with a set of guidelines that are like the ultimate playbook. Let's break down these rules in a way that won't have you reaching for a dictionary or scratching your head in confusion.

The Shower: Your Home's Splash Zone

Think of your shower area as a mini-water park where the main attraction is keeping all that water contained. Here’s how:

  • For Showers With a Bit of a Step: Whether it's a hob, step-down, or just level with the rest of the floor, the bottom line is the same – the floor needs to be completely watertight. That includes any raised bits.
  • Walls: They need to join the no-leak club up to 1800 mm above the floor. It's like drawing an invisible shield around your shower to keep the rest of your bathroom dry.
  • Corners and Cracks: Anywhere walls meet or where the wall says hello to the floor, there's gotta be a waterproof handshake, ensuring not even a drop of water can sneak through.
  • Holes for Plumbing: Every little opening for your showerhead or taps must be sealed up tight, so water only goes where it's supposed to.

And if you're using a preformed shower base? The same rules apply, except you don't have to worry about making the base itself waterproof – it's already got that covered.

Outside the Splash Zone

Moving away from the shower doesn't mean we can forget about water. Here's what you need to know:

  • Flooring Fundamentals: If your floor is made of something solid like concrete or fiber cement, it needs to resist water. What about timber floors? Those need to be fully waterproof to prevent any sneaky leaks from causing damage.
  • Where Walls Meet Floors: This junction is a prime spot for water to try its luck, so it's gotta be waterproof. Using a flashing? Make sure it extends a good 40 mm outwards.

Next to Baths and Spas

Baths and spas also have their own set of rules to keep them from turning your bathroom into a swamp:

  • Floors Near Baths/Spas: Just like with showers, solid floors need to resist water, while timber ones need to be totally waterproof.
  • Walls: For baths and spas snug against a wall, the wall needs to be water-resistant up to 150 mm above the bath or spa, covering any surfaces below the lip.
  • Corners and Edges: These spots need to be waterproof, especially right where the wall kisses the floor along the edge of your bath or spa.

Special Considerations for Inserted Baths and Spas

  • Shelves and Ledges: Got a shelf or ledge next to your bath? It needs to be waterproof, complete with a water stop under the lip of the bath or spa.
  • Walls Around Baths/Spas: They should be waterproof up to 150 mm above the bath or spa, providing an invisible barrier against water.

Other Areas Needing Waterproof Attention

Sinks, Basins, and Laundry Tubs

For walls connecting vessels like sinks, basins, or laundry tubs, the walls must be water-resistant to a height of not less than 150 mm above the vessel for its entire length, especially when the vessel is within 75 mm of a wall.

This ensures that splashes and spills don't lead to water damage. Additionally, any wall junctions where a vessel is fixed, and tap and spout penetrations must be waterproof to prevent leaks.


In laundries, the floor must be water-resistant, safeguarding against potential water damage from spills or leaks. The junctions where walls meet floors also need to be water-resistant, and if flashing is used, it must extend at least 40 mm horizontally. This creates a seamless barrier against water ingress.

Waterproofing Systems

Updates to the waterproofing standards distinguish between systems that are deemed waterproof and those that are water-resistant, based on the materials used and their application.

Materials Deemed Waterproof

The following materials are recognised as waterproof:

  • Stainless steel is known for its durability and resistance to corrosion.
  • Flexible waterproof sheet flooring material with waterproof joints, providing a seamless barrier against water.
  • Membranes complying with AS/NZS 4858, ensuring a high standard of waterproofing efficacy.
  • Waterproof sealant is essential for sealing joints and penetrations to prevent water ingress.

Water-resistant Substrates and Surface Materials

For a waterproofing system to be considered water-resistant, it must utilise certain materials in conjunction with others specified in the standards:

  • Walls: Options include concrete treated to resist moisture movement, cement render, compressed fibre-cement sheeting, water-resistant plasterboard, and masonry—all adhering to respective Australian Standards.
  • Floors: Concrete slabs and compressed fibre-cement sheeting supported on a structural floor are deemed suitable.
  • Surface Materials: For walls, thermosetting laminate and pre-decorated compressed fibre-cement sheeting are among the choices. Floors can benefit from tiles and water-resistant flexible sheet flooring materials, provided they're used in conjunction with an appropriate substrate.

These rules and materials are designed to make sure buildings can deal with water problems, keeping the structure strong and the air inside clean. By following these guidelines, homeowners and builders can protect their homes from water damage.

Navigating Compliance

Ensuring your building project ticks all the boxes for moisture defense can feel like navigating through a maze. But with the right know-how and resources, it's more like following a well-marked trail. Here’s how to keep on the straight and narrow:

  • Know the Rules
  • Partner with Pros
  • Keep Up with Updates
  • Documentation is Key


Think of these waterproofing standards not as hoops to jump through, but as your blueprint for a home that’s safe, sound, and secure. It's an investment that pays dividends in comfort, durability, and peace of mind. 

After all, a home that’s built to last, and protected from the ground up, is more than just a building; it’s a legacy.

So, let's shift our perspective. Let’s see these guidelines for what they truly are: a smart, forward-thinking approach to creating homes that not only stand the test of time but also provide a haven for those we hold dear. 

Here’s to building right, investing wisely in our homes' futures, and enjoying the peace of mind that comes with knowing we’ve done our best to keep our sanctuaries dry and cosy, come rain or shine 🏡

Frequently Asked Questions (FAQs)

Can you waterproof your own home?  

It's really important to note that rules can differ state by state. For example, in Queensland and NSW, only a certified licensed professional can do the work.

Where do these standards apply in a building?  

These standards apply to various areas susceptible to water exposure, including bathrooms, kitchens and laundries. Essentially, any area that might come into contact with water should be waterproofed according to these guidelines.

How often should waterproofing be inspected or replaced? 

Waterproofing doesn't last forever. It's advisable to inspect waterproofed areas every few years for signs of wear and tear, such as cracks or peeling. Typically, waterproofing in high-use areas like showers might need attention sooner than less exposed areas. A professional can give you a more accurate assessment based on your specific situation.

Are there different types of waterproofing materials approved under these standards?

Yes, the Australian Standards approve various waterproofing materials, including membranes, sealants, and coatings. The choice of material depends on the specific requirements of the area being waterproofed, such as its exposure to water, the type of substrate, and whether the area is indoors or outdoors.

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