Navigating waterproofing bathroom standards in Australia

by | Dec 12, 2023 | Advice & inspiration, Building basics & regulations

Quality waterproofing is easy to take for granted, yet it plays an essential role in every household. A waterproof barrier installed in all the wet areas of your house – including the bathroom, toilet and laundry – can prevent moisture penetration and water damage in the future which can lead to major issues. Let’s take a look at waterproofing bathroom standards in Australia and why they’re important.

Why is waterproofing important when building a new home?

Waterproofing any domestic wet area of your house is an essential step in the building process as it can potentially protect your home from significant damage. Moisture and water leakage can cause a wide range of issues that can wreak havoc on your new home, especially over a long period. Some of the potential issues include:

  • Mould: This is not only an eyesore, but can also be dangerous for your health.
  • Plasterboard decay
  • Rising damp
  • Rot in timber floors
  • Water damage to flooring, ceilings and walls
  • Serious structural damage to your home’s frame, support and foundation.

The structural damage that can be caused by water damage is no laughing matter, and in severe cases can compromise the safety and foundation of your home and can cost thousands, even tens of thousands, of dollars to fix. Though timber is particularly vulnerable to water damage, steel, concrete and brick can all be compromised by excessive water damage. This really is a case where prevention is the best cure.

How Does Waterproofing Work?

When building a new house or performing a renovation, bathroom waterproofing is performed before tiles are installed. A specialized waterproofer or a tiler with qualifications to waterproof will perform the job. The task will involve applying a waterproofing product either sheets or a waterproof membrane to the surface of bathrooms. The whole project should take about 2-3 days and involve the following steps:

  • The area will need to dry and clean before all joints, floor penetrations, and wall floor junctions are sealed with silicone.
  • Once the silicone sets, the first layer of waterproof membrane can be applied.
  • After leaving to dry overnight, this initial coat will be inspected. Assuming everything is good, a second layer will be applied and left for another 24 hours.

The waterproof membrane will need to dry completely before any further work can be undertaken. This can take a few days depending on the climate you’re working in. It’s also important that no following work (tiling and so on) damages the membrane.

Areas that will need to be waterproofed include:

  • shower floor
  • whole bathroom floor
  • exposed surfaces vulnerable to water

What are the Australian standards for bathroom waterproofing?

The National Building Code has a section dedicated to the expected requirements when it comes to waterproofing work that include the following guidelines:

  • Shower floors must be completely waterproofed and shower walls must be waterproofed up to a height of 1,800 mm.
  • Bathroom walls must be waterproofed up to a height of 150 mm
  • The step down from the shower to the floor must be waterproofed to a height of at least 100 mm.
  • If the bathroom is not on the ground floor, the entire bathroom floor must be waterproofed.
  • If the bathroom floor contains any wood, the entire bathroom floor must be waterproofed.

It’s important to remember that the above are just the minimum requirements according to the building code of Australia. Depending on factors such as your home design, the environment you’re building in and the types of rooms your home has, you may need to take additional waterproofing measures to ensure your house is secure.

How much does bathroom waterproofing cost?

Every homeowner wants to know how much things cost, especially with rising living costs. The cost will vary depending on a few factors including the size of your bathroom, your location, and how complex the overall project is. On average, waterproofing will cost around $500 – $750 for an average-sized bathroom.

We have found contractors who will charge as little as $40 per square metre, but this is on the low side of the scale, so expect to pay a little more than this, especially if you’re in a rural area where tradies are in shorter supply or will need to travel.

Can I DIY bathroom waterproofing?

There are plenty of jobs you can perform yourself, but waterproofing is best left to the pros. Waterproofing is more difficult than it may first appear, and because there are strict standards you meet to meet, we wouldn’t recommend performing waterproofing your bathroom yourself. In fact, in many states, including Queensland, it’s a legal requirement that a professional perform the waterproofing for a new house.

Beyond legal requirements and avoiding fines, there are plenty of practical benefits to having a professional waterproof your bathroom floor, shower walls and floors, and other areas. A poor waterproofing job can lead to water penetration which means you’ll end up with the same issues you would’ve had if you hadn’t waterproofed at all. Like many problems, water damage is best dealt with as soon as possible. If you have the false security of a job well done, you may not address the problem until it’s gotten much worse. How much it costs to hire a professional to waterproof your home, it’ll be nothing compared to how it will cost to fix structural damage to your house.

How are bathroom waterproofing standards enforced?

Australian waterproofing standards are taken very seriously, both in commercial and residential buildings. During your build, your home will need to be inspected to ensure everything is up to code and safe. While this may sound like a pain, it is a great way to ensure everything in your home is up to Australian waterproofing standards and you won’t face troubles later on.

Are there any consequences to ignoring bathroom waterproofing standards?

Chances are, if you ignore bathroom waterproofing standards, this will be picked up by a home inspector and you’ll be required to remedy the situation before you’re allowed to proceed. Delays in buildings are a fact of life, but they can also cost you money and be stressful, so it’s best to avoid them when you can.

The biggest consequence of ignoring bathroom waterproofing standards is that you’re leaving your home vulnerable to some serious damage. Fixing water damage is time-consuming, expensive and stressful. Plus the waterproofing will be redone, so any money you save by not doing it correctly will be a short-lived benefit.

How to find a certified professional?

In Queensland, it’s a legal requirement that whoever performs a waterproofing job is a licensed professional. However, even licensed people vary in quality and skills, so how can you ensure you find the right person for the job? Here are some questions to ask your potential waterproofer:

  • Are you licensed?
  • Is your business insured to work in my home?
  • Can you provide a detailed, written quote? (be sure the quote details what the price covers)
  • Do you have any references?
  • Have you completed a project similar to this before?
  • What warranty do you offer on the work?

We recommend getting quotes from at least three different waterproofers as this will provide you with an idea of what’s available and also give you some options.

Buildi are here to help you throughout your building journey! Book your free consultation today!


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