The vapour barrier that stopped at the slab edge
A membrane only works if it is continuous.
In short: A barrier laid short of the slab edge is not a partial barrier. It is an opening.
What the barrier does
It separates the concrete from ground moisture. The performance depends entirely on it being one unbroken layer beneath the whole slab.
What we recorded
The polyethylene stopped before the slab edge on one side of the lot, leaving a strip of the pour sitting directly on the ground.
Why it is not a small thing
Moisture entering at any point travels through the slab, and the first symptom is usually a floor covering lifting well after handover.
The fix while it is open
Extend the sheet, lap it correctly and tape the joint. Twenty minutes of work before the truck arrives.
After the pour
There is no remedy that does not involve the slab itself, which is why this is a pre-pour item and nothing else.
Written by the Owner Inspections team from inspections carried out in Pakenham East. Licensed building practitioners, Building & Plumbing Commission registration CDB-U 53425.
