Moisture Damage to Sub-Floor Foundation Wall

A non-destructive moisture meter has detected elevated readings in wall or ceiling linings at the time of inspection. Elevated readings alone do not confirm the source - they indicate that water is present in a material and that further investigation is warranted to rule out active leaks, drainage failure, or concealed termite activity.

Failed or missing sealant at the benchtop-to-splashback junction allows water to track behind the cladding and into the wall cavity, leading to substrate damage and potential mould growth. This junction is one of the most commonly missed maintenance items in kitchens across Perth's mid-century and newer housing stock.

Elevated moisture readings on wall linings next to bathrooms and showers indicate water is escaping the wet area - either through a failed waterproofing membrane or a leaking pipe inside the wall cavity. Left unaddressed, trapped moisture breaks down plasterboard, promotes mould, and can rot the framing behind the lining.

Grout failure in shower recesses is one of the most common moisture-pathway defects our inspectors record, present in 9.4% of all reports. Deteriorated or missing grout - including at screen junctions and wall-floor junctions - allows water to migrate behind tiles, saturating the substrate and ultimately causing waterproofing membrane failure, tile de-bonding, and concealed wall framing damage. AS 3740 requires shower wet areas to be fully waterproofed; grout condition is a primary indicator of whether that waterproofing system remains effective.

I inspected the bath hob, step-down, and vertical wall returns and could not confirm a continuous waterproof membrane behind the tiling. Reference: AS 3740. In my experience overspray and splash then tracks into the sub-tile substrate over time. I see this most on renovations completed before the post-2004 tightening, and still on recent unlicensed work.

I ran water in the shower recess and it ponded on the floor rather than draining cleanly to the waste - I measured a fall flatter than the 1:80 reference I work from (AS 3740). In my experience standing water then loads the grout lines, saturates the membrane at the low point, and tracks under the hob into the adjacent room. I often see this where the screed has been laid flat to suit a large-format tile layout.