Window and door defects in Australian residential construction

What it is

Windows and external doors are covered by AS 2047 (Windows and external glazed doors in buildings) for the system and AS 1288 (Glass in buildings) for the glazing. NCC Volume Two adopts both for residential work. Internal doors are not within AS 2047 but still need to meet the operability and tolerance requirements in state tolerance guides.

Common defect categories

Wind rating mismatch is a primary failure point. AS 2047 specifies window ratings N1 through N6 for non-cyclonic regions and C1 through C4 for cyclonic regions. A window rated N2 installed in an N4 wind area will not survive design wind events and is non-compliant from day one. Tribunals in coastal QLD and NT see this on most claims involving water entry during storms.

Safety glazing failures are a life safety issue. AS 1288 requires Grade A safety glass in doors, side panels next to doors, low-level windows, bathrooms, pool fencing and any pane below 500 mm from the floor. Using float glass in a place where AS 1288 demands toughened or laminated glass is a major defect. NCAT awards full glass replacement plus consequential costs.

Head flashing failure is the most common water entry path. Every window in a cavity wall needs a head flashing extending up behind the wall wrap and over the window head. When the flashing is short, tucked under instead of over the wrap, or missing entirely, water tracks down the cavity and into the room. Builders who install windows after sarking goes up commonly create this defect.

Inadequate sealing covers the perimeter between the frame and the structural opening. AS 2047 requires backing rod and approved sealant or expanding foam plus a continuous bond. Crews who shove offcuts of insulation into the gap fail this. Air infiltration and water entry follow.

Out-of-square frames cause door catching and locking failure. Tolerance guides from QBCC and NSW Fair Trading both allow no more than 5 mm out of square across a typical door opening.

Who is liable

Window and door defects sit inside both warranty windows. Failure causing water entry to structural elements triggers the six-year major defect warranty. Operational issues such as sticking doors fall inside the two-year non-structural window. Builder is liable for installation. Window supplier is liable for product compliance to AS 2047. Glazier is liable for the glass selection.

NCAT, VCAT and QCAT decisions on window defects routinely require manufacturer test certificates to prove the rating supplied matched what was installed. When certificates cannot be produced, tribunals order full replacement at the builder's cost.

TradeLens risk flags

Files should be flagged when any of these are missing. Site wind classification on the build file. Window schedule with N or C rating against each opening. AS 1288 schedule of safety glazing locations. Head flashing detail in the wall section drawing. Photo records of perimeter sealant install. These five drive most successful window and door claims.

Typical rectification cost

Replacing a single non-compliant window is 1200 to 4500 dollars depending on size. Full re-flashing across a house elevation is 4000 to 10000 dollars. Replacing all windows on a coastal home where the wind rating was wrong runs 30000 to 90000 dollars. These claims sit in the upper bracket of AU tribunal awards.