Mulch and Garden Beds Against House
Organic mulch and irrigated garden beds placed directly against the external walls create a moisture-rich, cellulose-rich environment that is attractive to subterranean termites and conceals the slab edge from visual inspection. AS 3660.1 and AS 3660.2 identify direct contact between landscaping materials and the structure as a conducive condition requiring correction.
Severity rationale
Across 2,326 observations the modal score is 3, with 70% of findings at exactly that level. Score 4 accounts for only 2.4% of observations, typically where mulch is piled against fibro or weatherboard cladding or where an active irrigation system has kept the contact zone wet for multiple seasons. Scores of 1 are rare (0.1%) - isolated to beds just grazing the wall with no irrigation present. The defect is widespread (present in 30% of inspected properties) but the majority resolve with straightforward landscaping adjustments.
Causes
- Landscaping installed with garden beds running up to and against the external wall cladding
- Bark or wood-chip mulch placed within the inspection zone, often supplemented by drip irrigation that keeps it moist year-round
- Raised garden-bed timber edging or sleepers set hard against the brickwork, trapping moisture at the slab face
- Turf or ground-cover plants grown to the wall line, obscuring the slab edge and weep holes
- Post-handover landscaping additions that were not reviewed against termite-management requirements
Symptoms to look for
- Mulch, bark, or organic material visible in direct contact with external wall cladding or brickwork
- Garden bed soil level at or above the slab edge, preventing the required 75mm of exposed concrete
- Weep holes in the base course of brickwork blocked or hidden by garden material
- Irrigation outlets or soaker hose running within 300mm of the wall, keeping the perimeter soil wet
- No clear inspection zone visible between garden bed and wall at any external elevation
Remedies
- Pull garden beds back to leave a clear 75–150mm gap between the bed edge and the external wall, ensuring the slab edge and weep holes are visible
- Replace organic mulch within 500mm of the structure with inorganic alternatives such as pea gravel or crushed rock
- Re-direct irrigation to avoid wetting the building perimeter; move soaker hose at least 500mm from the wall line
- Book an annual termite inspection (AS 4349.3 / AS 3660.2) to confirm no concealed entry has occurred during the period of contact
Where we see this most
These suburbs show the highest concentration of mulch and garden beds against house in our inspection data (minimum five observations). Click a suburb to see its full defect profile.
Worth asking our inspector about this specifically.
Clearing the contact zone is low-cost work that removes a recognised conducive condition. Where irrigation is active and the bed has been against the wall for more than one season, we recommend a termite inspection before disturbing the mulch in case activity is present.