How to waterproof laundry while keeping floor tiles?

Davosz

I'm currently working through the stages of my DIY laundry renovation. Previously we had a small laundry with a simple metal trough with the floors and walls tiled.

I have removed the tiles off the wall and the backing cement sheet, and patched all of the holes and replaced missing plaster that was covered by the cement sheet.

My question is the best way to waterproof what is required, keeping the floor tiles, with plaster wall, and keeping in mind the kaboodle cabinetry to be installed against the wall.

There is also a small gap where the floor tiles meet the plaster wall, due to the cement sheet for the walls previously sitting in between.

MitchellMc

Welcome to the Bunnings Workshop community @Davosz. It's wonderful to have you join us and many thanks for your question on waterproofing.

Waterproofing in wet areas is designed to be applied over the substrate and under the tiles, forming a continuous barrier. That means in a typical system, it starts at the floor and runs up the walls, all tied together before any finishes go on. Because of that, trying to retrofit waterproofing while keeping existing floor tiles in place is quite difficult as you can’t properly lap the wall membrane into the floor membrane, which is what makes the system effective.

That said, a laundry isn’t always classified the same as a bathroom in terms of waterproofing requirements. In many cases, full floor waterproofing isn’t mandatory, and the focus is more on splash-prone areas. For example, behind and around the trough or sink. So, depending on your setup, you may not actually need to waterproof the entire space.

For your situation, with plaster walls and existing floor tiles, a common approach would be:

• Ensure that gap at the base of the wall is filled/sealed (flexible sealant or appropriate filler)
• Apply a waterproofing membrane to the wall areas that are likely to get wet (e.g. behind the laundry tub), prior to installing any splashback or lining
• Make sure cabinetry (like your Kaboodle units) is installed in a way that doesn’t trap moisture against untreated surfaces

The tricky part is that without removing the floor tiles, you won’t achieve a fully compliant “tanked” system if one is required in your area.

Because regulations can vary and waterproofing is tied to compliance and insurance, it’s a good idea to check with a licensed waterproofer. They can confirm whether your laundry actually requires full waterproofing and, if so, whether it needs to be done by a licensed professional to meet local codes.

Please let me know if you have any questions.

Mitchell