In short: Membrane is only as good as what it is stuck to. In an upstairs wet area in Manor Lakes, it was stuck to particleboard.
What we found
On a July 2026 waterproofing inspection, the first floor wet area had membrane applied directly over particleboard flooring. The same visit recorded damaged membrane and walls with thick lumps of membrane that would have pushed tiles out of plane.
Why the substrate matters
The Housing Provisions list materials suitable as water resistant substrates in wet areas. Particleboard swells if it ever gets wet, and a floor that moves will crack grout and eventually the membrane above it.
Why upstairs raises the stakes
A failed ground floor shower wets a slab. A failed upstairs shower wets a ceiling, a living room and sometimes electrical fittings below. Many Manor Lakes homes now have their main ensuite upstairs.
What to ask for
Before tiling, ask the builder to confirm the substrate is a compliant wet area material or provide the approved alternative. Once tiles are down, the only check left is running the shower at handover and watching the ceiling below.
Written by our local inspection team from work carried out in Manor Lakes. Licensed building practitioners, Building & Plumbing Commission registration CDB-U 53425.
