Waterproofing is the most common serious defect
Waterproofing failures account for a large share of building claims in Australia, and they are almost entirely preventable. The membrane is covered by screed and tile within days, so once it is hidden you have no visibility for years — until the damage appears somewhere else in the house.
What to check before tiling starts
- Coverage and turn-ups. The membrane should run up the walls to the required height, higher in the shower area, and be continuous. Look for thin patches and pinholes.
- Junctions and penetrations. Corners, wall-floor junctions, waste outlets and tap penetrations are where failures start. These should be reinforced with bond breakers and fillets.
- The substrate. The membrane should go onto a properly prepared, primed and dry surface. Applied over dust or a damp screed, it will not bond.
- Falls to waste. Water must run to the drain. Check with a spirit level and a bucket of water before tiling.
- Number of coats. Manufacturers specify coats and cure times. Ask which product was used and check the datasheet.
Photograph everything
Take dated photographs of the completed membrane before the screed goes down. If a problem emerges in three years, that photograph is your evidence and it is worth more than any conversation you remember having.
Get the certificate
Waterproofing must be carried out by a licensed applicator in most states, and a certificate or compliance declaration should be issued. Ask for it and keep it.