In NSW a landlord must fix mould caused by the building, such as a leak, a defective window or inadequate ventilation, while a tenant may be responsible for mould they caused by not ventilating. The practical protection for both sides is a dated record, so check for mould at three points: before a tenant moves in, at routine inspections, and between tenancies. Catching a moisture problem at any of those points is cheaper and less contentious than waiting for a complaint.
This is general information, not legal advice. NSW Fair Trading’s guidance and the Residential Tenancies Act 2010 are the authority on any specific case.
What the law says about mould
The NSW Government’s mould in a rental property guidance sets out the split:
- The landlord is responsible where mould developed from moisture because the landlord failed to repair a defect (its example is a defective window) in a reasonable time, or because the property lacked adequate ventilation. The landlord must keep the property in a reasonable state of repair even if mould was noted on the ingoing condition report.
- The tenant may be responsible where mould developed during the tenancy because they allowed moisture to build up, for example by never opening windows or not using bathroom fans.
- Tenants must report signs of mould or damp to the landlord or agent as soon as possible.
- Mould that creates a health risk may be an urgent repair.
Rentals must also meet seven minimum standards throughout the tenancy. Three bear directly on mould: the property must be structurally sound, have adequate ventilation, and have adequate plumbing and drainage. A bathroom fan that vents into the roof space, or a window that lets rain in, puts a landlord on the wrong side of these.
Before a new tenant moves in
The ingoing inspection is the cheapest point in the tenancy to find a moisture problem: the property is empty and there is no dispute about who caused what. Check:
- Bathroom and laundry ceilings and cornices, especially above the shower.
- Exhaust fans for real airflow and where they discharge. A fan ducted into the roof space rather than outside is a common, invisible cause of recurring ceiling mould; see exhaust fan venting.
- Window reveals and sills, especially south-facing rooms and older aluminium frames.
- The base of external walls and skirting for bubbling paint, staining or a musty smell.
- Subfloor vents, clear of garden beds, soil and stored items. Older Illawarra double-brick and weatherboard homes often have marginal subfloor ventilation to begin with.
- The roof void, where it can be safely reached, for staining at penetrations and valleys.
- A musty smell with nothing visible, which usually points to the subfloor or roof void.
Fill in the mould section of the condition report (the NSW form has a dedicated one) and take dated photos of every wet area. That record is what settles a dispute later.
During the tenancy
At each routine inspection, repeat the checks above and look for:
- new staining or spotting since the last inspection, however faint
- condensation pooling on sills, or a bathroom fan that has been disconnected or covered
- signs of an unreported leak: swollen skirting, a seasonal damp patch, stains that were not there before
When a tenant reports mould, treat it as information. Ask for photos and when it appears (after rain, after showers, all the time), because that often points to the cause before anyone visits.
Between tenancies
A vacant property is the best chance to investigate properly, and the one most often wasted on a clean and a repaint.
| Check | Look for | If you find it |
|---|---|---|
| Bathroom, ensuite, laundry ceilings | Spotting or peeling paint near the fan | Treat it and check the fan and ducting at the same time; see bathroom and ceiling mould removal |
| Behind wardrobes, external walls | Spotting on the wall or the backs of fittings | Find the cause before repainting; paint over live mould just hands it to the next tenant |
| Window reveals and under blinds | Fine black speckling | Clean and treat; note if it repeats a previous report |
| Subfloor and roof void | Musty smell, growth on the underside of floors or sarking | Commission a moisture investigation before deciding scope |
| Carpet and built-in cupboards | Odour or staining after a vacant winter | Assess whether carpet or underlay needs replacing |
If nothing turns up, photograph that too. A clean, dated between-tenancy record is what answers a later claim that the mould “was always there”.
When a professional inspection is worth it
A walk-through handles a small, obvious, one-off spot. Call in a mould inspection and moisture investigation when:
- mould has come back after cleaning, which means the moisture source was never found (see why mould comes back)
- there is a musty smell with nothing visible
- growth covers more than one room or has reached plasterboard, carpet or timber
- you need independent documentation ahead of a likely dispute, bond claim or insurance claim
Enquiries through this site go to an independent local contractor who inspects, reports and quotes in their own name.
Can a landlord charge a tenant for mould removal?
Only where the tenant caused it, and that turns on evidence of cause. Mould from the building (leaks, rising damp, a failed or missing fan, inadequate ventilation) is the landlord’s to fix. Mould generated by how the property was used, with working ventilation available and not used, may support a claim against the tenant, but a contested claim is decided by the NSW Civil and Administrative Tribunal (NCAT), not by either party. The NCAT and tenant mould claims guide covers repair orders, rent reductions and bond disputes from both sides. The landlord’s best evidence is the condition report, inspection photos and a record of when the tenant reported the problem and how quickly it was acted on.
An indicative composite example
This is an indicative composite example, not a real job. A weatherboard rental in the northern suburbs has two tenant reports of bathroom mould over two tenancies, each handled with a clean and a repaint. At the next vacancy the manager books a moisture investigation instead. It finds the exhaust fan was never ducted outside and has been pushing moist air into the roof space. Re-ducting the fan and treating the ceiling properly ends the reports; the repeated repaints had treated the symptom only.
Frequently asked questions
Who is responsible for mould in a NSW rental?
The landlord, where the mould comes from a building defect not repaired in reasonable time or from inadequate ventilation. The tenant may be responsible where they caused moisture to build up, for example by not using fans or opening windows. Cause is the test, according to NSW Government guidance.
Can a landlord charge a tenant for mould removal in NSW?
Only if the evidence shows the tenant caused it. Disputes go to NCAT, which will look at the condition report, inspection records and how the reported problem was handled.
Is mould an urgent repair?
It can be. NSW Government guidance says mould that is causing health risks may be an urgent repair, which carries faster obligations than a routine repair.
Does painting over mould before a new tenant moves in fix it?
No. Paint hides active growth without removing the moisture feeding it, so it comes back and the next tenant reports the same problem.
What should a between-tenancy mould inspection cover?
Wet-area ceilings, window reveals, the base of external walls, behind fitted wardrobes, subfloor vents and the roof void where safely reachable. Any musty smell without visible growth deserves a proper moisture investigation.
If a property you manage has a mould history or an open tenant report, describe it on the quote form with a few photos and the suburb and an independent local contractor can quote an inspection before the next tenancy.