Air Conditioner Overflow Not Diverted
The condensate overflow pipe from the air conditioning unit is discharging at or near the building perimeter rather than into a drain or away from the structure. Persistent moisture against the slab or wall base creates conducive conditions for termite ingress and can accelerate mortar deterioration over time.
Severity rationale
Across 1,337 observations the modal severity is 3, with 68.7% of findings at score 3 (918 cases) and only 13 at score 4. No observations reach score 5. The defect is almost never trivial (zero score-1 findings), but it rarely escalates to the most serious tier because the fix is straightforward once identified. Scores push toward 4 when the overflow is directed against a timber frame or slab edge in a high-termite-risk area, where moisture becomes a secondary conducive condition.
Causes
- Overflow pipe not connected to a stormwater drain or extended sufficiently away from the building
- Inadequate pipe length leaving the outlet too close to the wall base
- Improper installation by the original A/C contractor with no drainage plan
- Wall-mounted unit positioned where gravity-fed drainage runs back toward the structure
- Overflow outlet terminating against paving, garden beds, or soil adjacent to the slab edge
Symptoms to look for
- Wet or stained area on external wall or slab edge directly below the A/C unit
- Overflow pipe visibly terminating within 300mm of the building perimeter
- Persistent damp soil or moss growth alongside the wall where the unit is mounted
- Overflow pipe with no downpipe extension, dripping onto cladding or footings
- Pooling water or efflorescence on brickwork near the overflow outlet
Remedies
- Extend the overflow pipe well clear of the building perimeter - minimum 1m away from the wall base
- Engage a plumber to connect the overflow to a stormwater drain or soak well
- Re-route the pipe so it discharges onto an impervious surface with positive drainage away from the building
- Where an outdoor unit is close to garden beds, install a concrete splash pad under the outlet
Where we see this most
These suburbs show the highest concentration of air conditioner overflow not diverted in our inspection data (minimum five observations). Click a suburb to see its full defect profile.
Worth asking our inspector about this specifically.
This is a maintenance item that warrants attention before the next Perth summer cooling season. Where the unit is mounted near garden beds or a timber-frame wall, address it sooner - persistent moisture against a slab edge is a termite conducive condition.