Do I need a waterproof membrane under tile or a toilet flange?
Waterproof membranes prevent trapped moisture and water accumulation beneath cement board, tile, and toilet flanges. Without proper waterproofing, underlying layers can become wet, loose, or crack and shift over time.
Overview
People affected2 accounts across 1 forum
Workarounds found2 items attempted
Community agreement2 total upvotes
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
2 items+ Contribute
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Relying on conflicting advice from different sources or installing cement board and tile without extra liquid waterproofing.Did this help you?
- 2pulling out the tiles and considering patching or thinsetting over the loose membraneDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
r/HomeMaintenance2 people · September 2026
“Should I add a waterproof membrane liquid (like Aqua defense) over plywood?”source ↗
Ioiwin · r/HomeMaintenance · 1 upvotes
Where this came up
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