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Splish Splash: How to get waterproofing right

Faulty waterproofing continues to make it into the top building defects reported across Australia. Surprising if you think that the art of waterproofing has been around for thousands of years. The ancient Egyptians used bitumen to waterproof the pyramids to avoid the tombs of the Pharaohs being flooded each year by the river Nile, and yet, all too many bathrooms with insufficient waterproofing continue to cause major headaches for homeowners, trades, and insurance companies.

So why is it so hard to get it right?

Bad waterproofing can lie dormant for years, but it can cost a lot of money and time to fix when it raises its ugly head!


Let’s start at the beginning. What is all the fuss about?

Waterproofing is normally required anywhere there is a water outlet: so, think bathrooms, showers, and baths, as well as laundries and kitchen “wet areas”. Although these spaces are wet areas, there are some places you definitely don’t want moisture to get to!

Waterproofing a bathroom involves applying a physical barrier to the floors and walls to prevent moisture from penetrating the structure of the property. The aim is to prevent any moisture from passing through the materials.

Typically, a waterproof membrane is applied once the internal walls, ceilings and plasterboard are finished, and before the tiles are laid. If you’ve ever watched a bathroom renovation show you will have seen that (usually) blue-coloured liquid membrane that is usually rolled onto the floor and wall surfaces.

Why blue? It’s the universal colour for water and the striking colour makes it easy to see where waterproofing has been applied, highlighting gaps or any faults. You can also find waterproofing products that are green or other bright colours.



The Australian Waterproofing Industry Standard

An Australian Standard for waterproofing wet areas applied across Australia. It’s known as the Australian Standard AS3470 and applies to all waterproofing of domestic wet areas.

These set out the MINIMUM requirements when it comes to SHOWERS, WALLS, and FLOORS, but we recommend you speak to a certified waterproofing expert in your area to also talk about waterproofing the areas around your bath, toilet, and vanity units.


Key points to know!

  1. The whole shower floor must be waterproofed
  2. The shower walls need to be waterproofed up to 150mm
  3. The shower walls must be water-resistant up to 1800mm
  4. If you are looking to have an open shower (no shower door), the floor must be waterproofed to a minimum distance of 1500mm from the showerhead
  5. If your bathroom is on the second floor of your home, you are required to waterproof the entire floor
  6. Although not required by law, when it comes to ground floor bathrooms, most waterproofing professionals also recommend waterproofing the entire bathroom floor to provide peace of mind.

Different levels of risk are applied to bathrooms. The higher the risk area the more waterproofing needs to be applied.

⚠ ⚠ ⚠ High-risk areas = Showers

⚠ ⚠ Medium-risk areas = Bathtubs

⚠ Low-risk areas = Handbasins and Sinks


Do I need a professional or can I do it myself?

This depends on which State or Territory your property is located in. In some States, waterproofing must be done by a licensed professional, while in others your waterproofing service must provide you with a compliance certificate that indicates the work meets the Australian Standards. If you choose to do it yourself, you won’t be issued a compliance certificate.

  • Queensland and NSW require waterproofing to be done by a licensed waterproofing professional
  • In other States and Territories, the waterproofer must provide a statement of compliance once the work is done that it complies with the Australian Standard

Remember too that when it comes to selling your property you will have to show the compliance certificate or proof that any waterproofing works comply with the local regulations. Given how important waterproofing is to the longevity and value of your home, leave it to the professionals.


How much will waterproofing cost me?

This is like asking how long is a piece of string? A number of factors will influence price:

  1. How big is the bathroom or wet area?
  2. The quality of the materials used.
  3. Is it on the ground floor or second (or third floor)?
  4. Do you want the entire bathroom waterproofed or just a certain area?
  5. What is the current condition of the bathroom? This will influence any pre-work required.
  6. Are you looking to get someone to do the waterproofing and the tiling all in one?
  7. What’s the urgency of the job? Remember that waterproofing takes time to “cure” so factor in a realistic time frame to do the job. Urgent jobs tend to cost more, and you will have less scope to negotiate.

Indicative costs

Some waterproofers charge by the hour, others by the square meter.

For a standard ground floor bathroom, you should factor anywhere between $350-$850 for basic waterproofing works. Per square meter prices seems to range anywhere between $35m2 to $60m2 depending on some of the factors listed above.


How do I find a waterproofing contractor?

Make sure you plan ahead and leave yourself sufficient time to find a qualified and experienced professional to do the job.

To find a waterproofing expert in your area:

  • Ask your local tile shop or bathroom display centre for recommendations.
  • Find suggestions via common trade sourcing platforms such as,, or
  • The great thing about these sites is that you can check out customer ratings and feedback they received on previous jobs.
  • If your bathroom renovation is part of a larger home renovation project, your builder will be able to connect you with someone locally.
  • Google local waterproofing experts in your area.



10 questions to ask a waterproofing specialist before you hire them to do the job!

Regardless of how you find your waterproofing expert, make sure to ask the following questions. Write down each of their answers so that you can compare quotes and remember who said what.

  1. Are you a licensed waterproofing professional? Ask to see their license and verify it with the issuing board if you have any doubts.
  2. Are you insured to do the job? This includes general and public liability as well as workers compensation insurance.
  3. How long have you been in business?
  4. What kind of jobs have you done before?
  5. What kind of warranty do you offer?
  6. What waterproofing solution do you recommend/What products and materials do you use?
  7. How will the process work and what will the finished solution look like?
  8. Can I speak to previous customers to hear what they have to say about your work and service?
  9. Can you provide a written quote and specify what works are included?
  10. What is not included in your quote?

Don’t be embarrassed to ask these questions. All good trades professionals know that these questions are perfectly reasonable and in fact, tend to like customers asking these as it gives them an opportunity to differentiate themselves from their competitors.

As always, we recommend taking the time to get at least 2 if not 3 quotes, to allow you to truly compare on the basis of value, expertise and quality.