What it is
Wall or floor tiles stuck on with spots of adhesive instead of a full, solid bed.
Why it matters
Hollow gaps behind the tiles mean less support. Tiles can crack when knocked, sound hollow, and leave voids where water can sit in wet areas.
How we check it
We tap tiles to listen for hollow spots and use a thermal camera, which shows the glue pattern behind the tiles.
The fix
Remove the affected tiles and re-lay them on a solid bed of adhesive.
How common it is
Tiles stuck on with dabs of adhesive show up clearly through our thermal camera.
The standard
AS 3958; QBCC Standards and Tolerances Guide 2023, 12.1 and 12.2