Brisbane
Brisbane is a ridge-and-gully city built on old cut-and-fill subdivision, so the retaining question here is usually topography rather than soil. Much of the post-war and interwar housing sits on hand-cut benches held by timber sleeper walls that are now decades old, which makes repair-versus-replace the most common enquiry rather than a fresh wall. Brisbane City Council applies the standard state triggers with no local override: more than 1.0 metre of retained height, a surcharge load at any height, a wall within 1.5 metres of a building or another wall, or a wall forming part of a pool barrier.