Mould in a rental property is one of the most common disputes in NSW tenancy. The good news is that the law is clear on responsibilities, and a professional inspection with a written report can resolve the issue quickly for everyone involved.
This guide covers what NSW law says about mould responsibilities, how property owners and managers can resolve mould efficiently, and why surface cleaning never fixes the actual problem.
Quick answer: Under the Residential Tenancies Act 2010 (NSW), the property owner is responsible for mould caused by building faults (leaks, rising damp, poor ventilation). Tenants are responsible if they caused the issue through misuse. In practice, a professional mould inspection report is the fastest way to identify the cause and determine the right course of action.
How NSW Law Divides Mould Responsibility
The Residential Tenancies Act 2010 (NSW) requires property owners to keep the premises in a reasonable state of repair and fit for habitation. Mould caused by structural or maintenance issues falls within that duty. Tenants have a responsibility to ventilate, report issues promptly, and avoid actions that create excess moisture.
| Cause of mould | Usually responsible | Why |
|---|---|---|
| Rising damp or rainwater ingress | Property owner | Structural repair duty under RTA s.63 |
| Leaking plumbing or roof | Property owner | Repair obligation throughout the tenancy |
| Inadequate ventilation design (no exhaust fan, poor airflow) | Property owner | Premises must be fit for habitation |
| Tenant not reporting a known leak | Tenant (partial) | Failure to notify of an issue that worsened |
| Tenant blocking vents or creating excess indoor moisture | Tenant | Misuse contributing to moisture buildup |
| Tenant-caused water damage (overflow, appliance failure) | Tenant | Damage caused by tenant actions |
In most cases, the cause is a building issue rather than tenant behaviour. A professional inspection can identify the moisture source within minutes, which avoids weeks of back-and-forth between the tenant and property manager about who is at fault.
What Property Owners and Managers Should Do
When a tenant reports mould, the most effective response is a professional inspection and treatment rather than sending someone with bleach and a bucket. Surface cleaning does not meet the repair obligation when the underlying moisture source is still active, and the mould will return within weeks.
- Arrange a professional mould inspection to identify the moisture source and document the extent of the problem
- Get a written report that records the cause, the areas affected, and the recommended treatment
- Address the moisture source (repair the leak, improve ventilation, fix drainage)
- Engage professional treatment that addresses the root structure, not just the surface
- Keep the inspection report and treatment records on file for compliance and future reference
A professional inspection report protects the property owner by documenting exactly what caused the mould and what was done to fix it. If the cause turns out to be tenant behaviour, the report provides clear evidence of that too.
For property managers: A mould inspection report from a qualified professional gives you a clear document to share with the owner, the tenant, and your files. It takes the guesswork out of who is responsible and what needs to happen next.
What Tenants Should Know
If mould appears in a rental property, the most productive step is to report it to the property manager in writing straight away. Include photos and note when you first saw it. This starts the process and gives the property manager the information they need to arrange an inspection.
- Report mould and any visible moisture sources (leaks, condensation, damp patches) in writing as soon as you notice them
- Keep the property reasonably ventilated — use exhaust fans, open windows where practical, and avoid excessive indoor drying
- Allow access for inspection and treatment when arranged
- Do not attempt to clean extensive mould yourself — it disturbs spores, spreads the problem, and makes professional treatment harder
Reporting promptly and cooperating with the inspection process is the fastest way to get the issue resolved. Most property managers want to fix mould quickly because leaving it unresolved creates bigger problems down the track.
Why Surface Cleaning Never Fixes Rental Mould
Retail mould sprays, bleach, and vinegar remove the visible discolouration within minutes. The mould root (hyphae) embedded in plaster, timber, or grout is completely unaffected. Regrowth typically occurs within two to six weeks, and the cycle starts again.
- Surface only: Bleach lifts the colour but cannot penetrate porous building materials where the root structure lives
- Spore spread: Spraying mould without containment releases spores into the air, which settle elsewhere and start new colonies
- Moisture source untouched: No retail product can find or fix the leak, damp, or ventilation failure feeding the mould
- Creates repeat callouts: For property managers, a surface clean that fails in three weeks means another tenant complaint, another tradesperson visit, and another cost — professional treatment done once saves time and money
NSW Fair Trading treats mould as a building repair issue, not a cleaning issue. A surface clean that fails within weeks does not satisfy the repair obligation under the Residential Tenancies Act.
What Professional Mould Treatment Involves
Professional mould treatment starts with identifying the moisture source, uses industrial-grade products that penetrate below the surface, applies containment so spores do not spread, and backs the work with a guarantee.
Mould and Hygiene Solutions uses an Australian-made, non-hazardous, non-corrosive and environmentally friendly antimicrobial solution that kills 99.99% of bacteria and treats the root structure in the substrate, not just the visible surface.
- Professional inspection to identify the moisture source and document the extent of the problem
- Written report suitable for property managers, owners, and compliance records
- Full treatment of the substrate (plaster, timber, grout) using the antimicrobial solution
- Containment during treatment so spores do not spread to other rooms
- Advice on ventilation or repairs needed to prevent recurrence
- 12-month unconditional mould-free guarantee on the treated area
For rental properties, the written inspection report is particularly valuable. It gives the property manager a clear record of what caused the mould, what was done, and what ongoing maintenance is needed. That documentation protects the owner and satisfies the duty of care under NSW tenancy law.
Book a Professional Mould Inspection
Whether you are a property owner, property manager, or tenant dealing with mould in a rental, the fastest path to resolution is a professional inspection. It identifies the cause, documents the problem, and provides a clear plan for treatment.
Mould and Hygiene Solutions provides professional mould inspections and treatment across Newcastle, the Central Coast, Lake Macquarie, Hunter Valley and Port Stephens. Every treatment is backed by an unconditional 12-month mould-free guarantee. Visit mould inspections or mould removal to book.
