Waterproofing and tanking basics
The invisible layer that prevents the most expensive bathroom failures.
At a glance
Quick Checklist
Key points at a glance
- 1Tank all wet areas, not just shower
- 2Seal all corners and pipe penetrations
- 3Use proper tanking tape at joints
- 4Apply multiple coats of liquid membrane
- 5Get a warranty on the waterproofing
Questions to ask your installer
Take these to your next conversation with your fitter
- 1What tanking system will you use and is it guaranteed?
- 2How far will the waterproofing extend beyond the wet areas?
- 3How will pipe penetrations through the tanking be sealed?
- 4Is there a warranty on the waterproofing workmanship?
- 5Can I see photos of your previous tanking work?
- 6What happens if a leak develops - who is responsible?
💡 Tip: A good installer will welcome these questions. If they dismiss them, that's a red flag.
💡Myth vs Reality
Common Myth
"Tiles and grout are waterproof"
The Reality
Water absolutely gets through grout and behind tiles. Without tanking, moisture damages the structure beneath.
Common Myth
"Only showers need waterproofing"
The Reality
Bath areas, around toilets, and anywhere water regularly splashes should all be tanked.
What to look for
- •Tanking membrane or liquid waterproofing in wet areas is essential
- •All joints, corners, and pipe penetrations need sealing tape
- •Waterproofing should extend beyond the immediate wet zone
- •Building regs may require tanking in certain situations
Common mistakes
- •Assuming tiles and grout are waterproof (they're not)
- •Only tanking the shower area but not behind the bath
- •Skipping corners and edges where leaks most commonly occur
- •Using the wrong sealant that doesn't bond to wet area surfaces
Quality considerations
- •This is not where you save money - failed waterproofing is devastating
- •Quality tanking kits include corner pieces and tape for joints
- •Some systems offer manufacturer warranties when installed correctly
- •Liquid membranes should be applied in multiple coats for full coverage
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This guide is written to help you make informed decisions, not to sell you anything. Always discuss your specific situation with a qualified installer.