How to repair an uneven bathroom floor?

Question

II have a small uneven area that was under a hot water tank that i need to level and waterproof.

I dont need to tile or have it look pretty as I will be putting cabinets over the area.

Could you please recommend which products to use? Can I just clean the area and use a levelling liquid or would I need to prep some other way first?

Thanks!

EricL · Answer

Hello @ivanptr

Thank you for sharing your experience with our members. Let me tag @Donna13 to make them aware of your recommendations.

Eric

ivanptr · Answer

Just an idea 😅—after you do the exploratory work like our GOAT (Greatest Of All Time) @MitchellMc suggested, and find something to level it, I would lay down a nice, solid, bathroom-grade floor tile and use a reliable grade of epoxy grout to fill the gaps. I’ve found that many shower repair companies nowadays use this method, and it proves to be quite effective even if the waterproofing underneath the old tiles has already deteriorated. As long as the grout is solid and the tiles themselves are waterproof, it still provides relatively good protection.

​However, this method only waterproofs that specific corner... you might want to do it for the whole bathroom, or at least the entire wet area.…

MitchellMc · Answer

Welcome to the Bunnings Workshop community @Donna13. It's marvellous to have you join us and many thanks for your question on repairing a bathroom floor.

The main objective here is to create a flat, stable surface, but it's a little difficult to tell exactly what is happening with the floor construction from the image alone.

It appears that the tiled area is installed over cement sheeting, while the section where the hot water system sat has several different flooring layers, including what looks like timber flooring with another material over the top. Before levelling the area, I'd recommend some exploratory work to determine the full floor build-up.

Rather than simply pouring a self-levelling compound over the existing surface, I would suggest removing the loose and damaged flooring materials back to a sound substrate, ideally down to the timber joists if required. Once you have established a solid base, you can install compressed fibre cement sheeting to bring the area back to the appropriate height and provide a stable surface.

If additional levelling is needed after the cement sheeting is installed, a floor levelling compound can then be used over the top.

Regarding waterproofing, it's important to note that waterproofing only this section is unlikely to be effective. Waterproof membranes need to be installed as one continuous system across the entire wet area before tiling. Any attempt to waterproof just this patch would leave a break between the existing floor and the new membrane, compromising its effectiveness.

My recommendation would be to continue removing the old flooring layers until you have enough depth to install either:

* Compressed fibre cement sheeting alone if the area will be completely covered by cabinetry and won't be exposed to water; or
* Compressed fibre cement sheeting followed by tiles if you want to restore the floor properly and maintain a suitable wet-area surface.

Let me tag @diyaaron, @ivanptr, @sportsport, and @AnnaH1, to see if they have any thoughts.

Please let me know if you have any questions.

Mitchell