Finding the vapour barrier gap far too late

In short: A barrier missing in sections is only fixable before the concrete. After that it is a permanent unknown.

What the barrier does

It separates the slab from ground moisture and only works as one continuous layer beneath the whole pour.

Vapour barrier missing in sections along a Craigieburn slab edge, visible at frame stage because the edge was still exposed.

By frame stage the concrete had been down for weeks. Nothing about what sits beneath it could be changed.

An hour on site the day before the pour, and a few metres of plastic to correct.

Every slab finding is a pre-pour finding. There is no second chance at any of them.

Written by our local inspection team from work carried out in Craigieburn. Licensed building practitioners.

More new construction stage inspections guides for Craigieburn

2 March 2026 · 7 min read

A structural element, removed by somebody who needed the space.

1 April 2026 · 5 min read

Two minutes of work, deferred until it becomes a plumber's callout.

8 July 2026 · 6 min read

A room that will not warm up, and a cause nobody can see.

Questions Craigieburn owners ask about this

Can the barrier be repaired afterwards?

Not beneath a poured slab. What can be managed afterwards is drainage and moisture around the perimeter, which is mitigation rather than a fix.

What are the consequences?

Moisture movement into the slab, which typically shows up much later as flooring lifting or persistent damp at the edges.

How do I avoid this?

Book the slab pre-pour stage and tell us as soon as a pour date exists, because that date moves and the window does not reopen.

Is this common?

Common enough that the vapour barrier is the first thing checked at every pre-pour inspection we attend.