Waterproofing a Bathroom: How To Know If It’s Been Done To Australian Standards

Waterproofing a bathroom to Australian Standards is crucial during building, but it doesn’t always happen.  So, if you’re the person on the other end, the homeowner or buyer, how do you know the bathroom waterproofing is to code?  We will explain this in this article.

The addition of a waterproof barrier installed around the bathroom walls and floors is what stands between water getting into the substructure of your house or not. When waterproofing isn’t installed or is incorrectly installed, the water penetration can cause significant structural damage let alone introduce the perfect damp environment for destructive termites and mould.    

What is a waterproofing barrier?

A waterproofing barrier is the basic building block of a bathroom waterproofing system and a necessary process to protect the integrity of your home. Bathroom waterproofing involves applying a physical barrier to the floors and walls to prevent moisture penetration into the structure of your home. The waterproof membrane is applied before tiles are laid. While this might not seem like the most exciting thing to read about, it’s a critical building feature, one that some people might have overlooked!

What are the waterproofing bathroom Australian Standards?

Australian Standard 3740-2010 outlines the rules for waterproofing a bathroom. Like with any standard, there are different and varying degrees of compliance. In most cases, a qualified builder or renovator will ensure compliance, but sometimes this isn’t always the case, particularly in the case of home DIY. Therefore, it’s important to ensure that the waterproofing work is done to a high standard. It’s also important to pay close attention to how your waterproofing will be applied in a new build or renovation. If you can’t, you run the risk of having a sub-standard waterproofing job installed.

The Importance of Waterproofing

Some frustrating things can happen without proper bathroom waterproofing. For example, cracks that can appear in the foundation or joints exposed to water can lead to severe structural problems like leaks, spalling, and deterioration.

For timber-built properties like post-war homes or Queenslanders, and properties with a timber floor bathroom and wooden cabinetry, moisture from the water penetration will lead to rotting, delamination of wood, and moulds. 

Mould growth is a significant health hazard. Exposure to moulds can lead to allergies, asthma, irritation, and fungal infections. 

How to check if waterproofing has been done to Australian Standards

The Building Code of Australia and Australian Standards (AS 3740-2010) set out the minimum requirements of waterproofing a bathroom. All bathrooms in Australia must comply with these standards, as follows:

  • The entire shower floor must be waterproofed
  • The shower floor and walls must be waterproofed up to at least 1800mm
  • The walls of your bathroom must be waterproofed up to at least 150mm
  • Over the hob or step down must be waterproofed to at least 150mm
  • If the bathroom floor is above ground level or made of timber, plywood, or particleboards, the entire bathroom floor must be waterproofed
  • Bathrooms with frameless showers should have the whole bathroom floor waterproofed, including the walls of up to a 1500mm radius.  
  • To add, some councils require waterproofing to be done by a licensed waterproof expert. Even if your council allows DIY waterproofing of bathrooms, it’s highly recommended that you engage a qualified service provider who can provide certification.

What to look for when buying a home

Checking for bathroom waterproofing isn’t as easy as just having a look. But there are some key identifiers that something is amiss and that water is getting through. These include: 

  • The bathroom floor feels spongy underfoot
  • The air smells musty
  • There is mould and mildew
  • The shower doesn’t fit into the wall space properly
  • There is an apparent water leak around the floor and walls
  • The walls are warped

If you identify any of these issues, they could be key indicators that there’s no waterproofing or that the current waterproofing isn’t up to code.

Alternatively, to be sure the bathroom has been waterproofed, consider these options:

  1. Obtain an Installation Certificate (written in English or using standard English phonetics, is required for bathroom waterproofing works in Australia)
  2. Ask the installer if they can show you a Certificate of Approval signed by Building Code Approvals (BCA) where the work was completed on time and according to specifications.
  3. Ask whether the bathroom waterproofing work has been conducted according to Australian Standard AS3740-2010
  4. Have an expert building inspector check the property for you. 

The absence of proper waterproofing in a bathroom causes far more problems than it should, thanks to unqualified installers and people trying to cut corners. So when you’re looking to buy a property, keep your corners perfectly squared by having a building and pest inspection. A qualified building inspector like Safeguard Inspections will be able to tell you whether or not the bathroom waterproofing is up to scratch.

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