How to repair torn waterproof membrane from tiles lifting?

parkyacon

Hello, my name is Linda.

I had some tiles in my shower wall that were lifted up, and the grouts around them were breaking away. While I was trying to remove the tiles, a small portion of what seems to be waterproof membrane has been torn.

I am wondering how I could repair this.

EricL

Hello @parkyacon

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your bathroom tiling.

What you’ve uncovered there does look like the waterproofing membrane, and unfortunately once that layer is damaged, it’s no longer doing its job properly. In a shower, that membrane is what stops water from getting into the wall structure, so even a small tear can allow moisture to track behind the tiles over time.

In practical terms, a proper repair isn’t just about patching the visible tear. For a waterproofing system to remain compliant and reliable, any repair needs to tie back into the existing membrane with the correct overlap, thickness, and curing process. That’s quite hard to achieve in a small, localised patch, especially in a wet area like a shower where failures tend to show up later as hidden damage.

While there are liquid waterproofing products available (for example, brush-on membranes you can get from the store), they’re really intended for full-system applications or larger, properly prepared areas. Using them as a spot repair over a torn section behind existing tiles can be a bit of a gamble, as you can’t guarantee continuity with the original membrane.

Given you’re in a shower, the safest and most durable approach is to treat this as more than a cosmetic repair. Typically, that means removing tiles back to the waterproofing line and reapplying the membrane correctly and then retiling. In many parts of Australia, waterproofing in wet areas is also a regulated trade, so a licensed water proofer is often required for work like this especially if you want peace of mind and compliance.

If you need further assistance, please let us know.

Eric