How Much Does Bathroom Waterproofing Cost? [2024]

When you're renovating your bathroom, there are some DIY jobs you can tackle, but waterproofing isn't one of them. Waterproofing wet areas must be carried out by professional waterproofer. If a leak develops it could cause a range of issues including plasterboard decay, mould, rising damp, peeling paint, and more serious structural damage. Remedying these are all likely to cost you more than waterproofing, so it makes sense to get it done right the first time.

This article will help you understand:

• Why your bathroom must be waterproofed
• Questions to ask before you hire a waterproofer
• How much they may charge

© Sydesign

Australian Standards for waterproofing a bathroom

Bathroom waterproofing is so important, it is mandated by law and must comply with Building Code Australia (BCA) and Australian Standard AS3740. The basic requirements are that:

• Shower enclosure floors must be thoroughly waterproofed
• Shower enclosure walls should be waterproofed to 1800mm
• Bathroom walls should be waterproofed to a height of 150mm
• If the bathroom floor contains or is made of timber or is on the 2nd floor or higher, it must be thoroughly waterproofed
• The area over the shower enclosure step and down to the floor must be waterproofed to a height of 100mm

How does bathroom waterproofing work?

Bathroom waterproofing is done before tiles are laid. In many cases, your bathroom renovator or tiler will include waterproofing in their quote. Otherwise a dedicated waterproofer will need to come in. Waterproofing products are typically sheets or a water based, flexible, high performance polyurethane membrane which is painted onto a surface.

The waterproofing process normally takes 2 - 3 days and involves:

• The area being cleaned and primed. All joints, floor penetrations and wall floor junctions are then sealed with silicone. The first coat of the waterproofing membrane can then be applied.
• This is allowed to dry overnight and then inspected to ensure it is complete. The second coat is then applied. This is left to dry overnight.
• The area can then be tested and then left to dry for a further 24hrs.

You’ll need to wait for your waterproofing to dry out completely before continuing with other work, which could be a couple of days, depending on the ambient temperature. It is very important that all subsequent work does not damage the waterproofing membrane, or you could risk the structural integrity of your home if you do have a leak.

© Sureseal Waterproofing

Does my bathroom waterproofer need to be licensed?

In New South Wales and Queensland, the person who undertakes the waterproofing must hold a current waterproofer's license.

The Building Commission NSW defines waterproofing as, “...work (that) involves any protective treatment of a dwelling designed to prevent the penetration of water or moisture into the dwelling or the protective treatment of wet areas in a dwelling designed to prevent the unwanted escape of water from those areas by using solid membranes or membranes applied by brush, roller or any other method.” Training involves completion of a Certificate III in Construction Waterproofing.

Some related trades, such as tilers, are sometimes also licensed to carry out waterproofing.

In other states and territories, a qualified waterproofer must issue a compliance certificate upon completion of the job. Make sure your waterproofer supplies you with a waterproofing certificate and warranty on completion of your job.

Hiring a bathroom waterproofer

When it comes time to hiring a waterproofer make sure they are right for your job. Some questions to ask them include:

• Are you licensed?
• Are you insured to work in my home?
• How long will my job take?
• Can you provide a written quote?
• Do you have references I can follow up?
• What warranty does your waterproofing product carry?

Tip: Get at least three quotes before you commit to hiring anyone, so you can compare price and level of service

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How much does bathroom waterproofing cost?

Bathroom waterproofing can cost as little as $40 per square metre, but that is the low end of the scale.

In general, expect to pay between $500 and $750 to completely waterproof an average sized bathroom. If the waterproofing is done in more than one bathroom or as part of a complete bathroom renovation, the cost may be lower. In some cases, such as large bathrooms, wet rooms or second storey bathrooms, the cost of waterproofing may be higher.

To get the best price and the best service, get quotes from several services and ask each of them to provide you with all the details about the scope of their service in their quotes. Because you want to know your bathroom will be fully waterproofed, choose the company with the best reputation rather than the one that offers the lowest price.

The best way of finding out the cost of your project is to get quotes from local bathroom waterproofers. This will give you a sense of what market rates currently are.

* All the costs and prices quoted were sourced at the time this article was written. They are indicative, may vary locally, are subject to market forces and should only be used as a guide.