Vapour barrier position on a Melton South slab
Under the steel, not over it.
In short: A barrier laid in the wrong plane cannot do the job it is there for.
What it does
It stops ground moisture rising through the slab into the house above.
What we found
The barrier lying over the steel rather than beneath it, which puts it in the wrong plane entirely.
Why it matters
Above the steel it neither protects the reinforcement nor blocks moisture the way the design assumes.
The related items
Mesh sagging, cover reduced, and beam widths moving during placement.
When to look
The day before the pour, which is the only time any of it is visible.
Written by the Owner Inspections team from inspections carried out in Melton South. Licensed building practitioners, Building & Plumbing Commission registration CDB-U 53425.
