Double brick to frame: what happens to the rating?

WA has had one major brickmaker since Austral closed its Cardup brickworks in mid-2023. Midland Brick is now allocating supply, and the state is funding Cardup’s restart, with new bricks expected from 2027. Builders are moving designs from double brick to brick veneer, and to timber and steel frames.

The house can look the same, but three things change in the walls at once. A framed wall usually insulates better. Double brick keeps a heavy inner leaf on the room side, which soaks up heat and releases it hours later, while brick veneer puts its brick outside the insulation. And studs carry heat past the insulation, steel more than timber. Since NCC 2022, NatHERS ratings count that heat flow through steel framing, so steel needs the right details: a thermal break or battens, and often a reflective cavity. Done properly, a steel-framed wall performs close to a standard timber one.

In Perth’s climate, double brick’s mass often counts in a rating, so the same design can lose stars when it is re-rated as a framed home. When it does, the answer isn’t always a list of upgrades: the design can change, or a Performance Solution under H6V2 can test it against the Code’s reference house. Try the wall lab