AS 4200 is the standard behind the wrap you see stapled to a house frame before the cladding goes on. It is easy to overlook, but that membrane is a big part of how your walls keep water out over the decades.
What AS 4200 actually means
AS 4200 governs pliable building membranes — the flexible sheet materials used as wall wrap, sarking and vapour barriers. It comes in two parts. Part 1 sets out the material requirements of the membranes themselves, including their vapour permeability and water resistance. Part 2 sets out how they must be installed — laps, fixing, and the way they meet flashings, windows and penetrations.
Where it applies in your new home
Wall wrap sits behind your external cladding; sarking sits under the roof. Both are second-line defences: they shed water that gets past the outer skin and manage vapour so the frame stays dry. In a warm, humid climate like South East Queensland's, getting the membrane and its installation right protects the frame from long-term moisture.
What VG Inspect checks against it
The membrane is checked at the pre-plaster (lockup) stage and, on the outside, at frame stage — while it is still visible and before linings and cladding cover it. An inspector looks at lap direction and overlap, fixing, and whether the wrap is properly sealed around windows, doors, pipe and service penetrations. Tears, missing laps and unsealed penetrations are the common findings.
What it does and doesn't cover
AS 4200 covers the pliable membranes and their installation. It is distinct from the wet-area waterproofing membranes governed by AS 3740, and from bulk thermal insulation, which is covered by AS 3999. Together these standards keep water out and comfort in.
A VG Inspect QBCC-licensed inspector (QBCC Licence 1318443) checks your building membranes before they are covered, and reports the same day. Call 07 3180 8041 or book an inspection online.