Air conditioner condensate and wet ground beside a Truganina slab
A small pipe can keep the clay at your footings wet all summer. What we found on a Truganina investigation and how it is fixed.
In short: Condensate from a split system is clean water, but where it lands matters. Discharged against the house, it wets the clay the slab sits on.
The investigation
A Truganina defect investigation in August 2026 recorded the air conditioner condensate drain as a defect in its own right.
What was wrong
The drain was made from an unsuitable type of pipe and stopped beside the house instead of discharging a suitable distance away. Through a hot summer that is a steady supply of water to one spot at the footings.
Why it matters on reactive clay
Truganina sits on basalt clay that swells when wet and shrinks when dry. A slab is designed for fairly even moisture around its edge. Constant wetting at one point is the kind of uneven condition that can lead to movement and cracking.
How it is fixed
Replace the drain with a suitable pipe and run it to stormwater or a suitable discharge point away from the dwelling. It is a small job compared with what it prevents.
Found at handover too
The same issue shows up at handover inspections, where condensate drains discharge straight onto the ground. It is worth raising before you move in.
Written by our local inspection team from work carried out in Truganina. Licensed building practitioners, Building & Plumbing Commission registration CDB-U 53425.
