Many Aussie houses (especially in the more northern parts) prior to the 60s were old fashioned post and beam timber (usually weather-board or chamfer-board clad) construction. But then concrete slab based construction (with prebuilt roof trusses) became more popular (read cheaper), and nowadays steel framing is not uncommon as well. Also differing construction styles are used, nowadays huge slabs of plywood are often used to provide torsional rigidity to the walls.

Masonry construction used to be the hallmark of the southern side of the continent, being based on 'traditional European/English' - also double brick or brick clad wooden framed houses were more the preserve of the more well to do, especially in the more northerly end.

My uncle the plumber said in the 60s that 'the (corrugated iron) roof held the (weather)board walls up.

Funnily enough, provided the roof trusses and beams are strapped down, and if roofing screws are used instead of the old fashioned 'lead head' nails, then Aussie houses can easily be rated quite high for cyclonic winds, as indeed revised building regs after Cyclone Tracy hit Darwin, the main problem being that legacy housing is usually not retrofitted to the higher 'tie down' standards.

Of course Cat 3 used to be the main high rating - Cat 5 rating is MUCH more expensive to construct, also involving architectural concepts such as taking care of large overhanging eaves, etc.