Five envelope checks before you sign off frame stage

Frame stage is one of the last moments when the working parts of a wall are visible. After the wrap, cladding and linings go on, defects are hidden behind finished surfaces and hard to prove. So the point at which an owner or developer is asked to sign off, or pay a progress claim, is a good moment to ask what has actually been checked.

This is not a substitute for a certifier's inspection or an engineer's sign-off. It is a guide to the envelope questions worth asking, and to how we approach them on our own projects.

1. Is the wall wrap installed as a system?

The pliable building membrane (wall wrap or sarking) is the second line of defence behind the cladding. It has to be lapped so water sheds downward, taped or sealed where the manufacturer requires, sealed to openings and free of tears. In NSW the wrap also has a role in moisture management: NCC 2022 sets condensation management requirements that include how vapour-permeable the membrane must be, depending on the climate zone. Ask which product is specified, and check it was installed to AS 4200.

2. Are the openings flashed in the right order?

Windows and doors are the most common entry point for water. The sill flashing or tray, jamb flashings and head flashing need to be installed in the correct order, before the unit is fitted, so that any water that gets behind the frame is directed back out. This is much harder to inspect after the cladding is on. Ask to see photos of each opening at this stage, and check that sealant is not doing the job of flashing.

3. Are penetrations and interfaces detailed?

Every pipe, vent, flue, cable and meter box that goes through the envelope needs its own flashing or seal, using a system that suits the product. Balcony, deck and terrace interfaces need particular attention: the membrane has to be in place and inspected before cladding covers it. Above-ground membranes follow AS 4654, and you can read more in our post on where buildings leak.

4. Is the cladding installed to the manufacturer's instructions?

Cladding systems come with installation manuals, and warranties usually depend on following them. Look for correct clearances above ground, decks and roofs, a drained and ventilated cavity where the system requires one, and compatible sealants and fixings. For masonry, check damp-proof courses, flashings, weepholes, wall ties and control joints.

5. Has the whole envelope been inspected and recorded?

At lock-up, before internal linings go on, someone with authority should walk the entire envelope and photograph every flashing, opening and penetration. Where the design or the risk calls for it, a hose test of windows, doors and critical junctions, or an inspection after a rain event, will show whether anything is leaking. If water is found, it should be traced, corrected and re-tested before the job moves on.

How we approach it

On our projects, roof, wall, cladding and lock-up checks sit on our stage-by-stage checklists, and the items that matter most to weatherproofing are hold points, meaning the next trade does not start until they are cleared. The lock-up inspection is by the site supervisor and a technical lead, with photographs, before internal linings. The details are on our How We Build page, and our Quality & Building Compliance policy covers the wider approach.

If you would like an independent look at an envelope before it is covered, or want to understand what your builder is checking, get in touch.

Sources

• NCC 2022 Housing Provisions, Part 10.8 Condensation management, Australian Building Codes Board
• Design and Building Practitioners Act 2020, section 6 (Building elements), NSW Legislation via AustLII

This article is general information, not advice for your project. Requirements depend on the building class, the approvals, the design and the products used, so confirm them with your certifier, engineer and the relevant standards. Full website disclaimer