In short: A waterproofing membrane is only as good as its bond to the surface beneath. On a Rouse Hill build in July 2026 it had been applied over dirt.
What we saw
At a waterproofing inspection in Rouse Hill in July 2026, the membrane in a wet area had gone down over a concrete surface that had not been cleaned, with dirt visible beneath it. Nails also stood through the shower recess membrane, and no water stop angle was fitted under a doorway.
Why the surface matters
Membranes rely on adhesion. Dust and debris stop the membrane bonding, and a membrane that is not bonded lifts, blisters and tears as the building moves. On another Rouse Hill job at the end of August, membrane peeled away in one pull for exactly that reason.
What the builder had to do
Remove the affected membrane, clean and prime the substrate and reapply, then deal with the nails and fit the water stop. All of that is straightforward before tiling and almost impossible after.
Written by our local inspection team from work carried out in Rouse Hill. Licensed building practitioners, NSW Fair Trading licence 366177C.
