Mould in Rental Properties: Tenant vs Landlord Responsibilities

Mould in a rental property creates tension. Tenants want it fixed. Landlords want to know who caused it. The law sits somewhere in between — and understanding your rights can save a lot of frustration.

Who is responsible?

Under Australian tenancy law, the answer depends on what caused the mould.

Landlord responsibilities

The landlord (or property manager) is responsible when mould results from:

• Structural issues — leaking roof, cracked walls, faulty plumbing, rising damp
• Building defects — inadequate ventilation design, missing exhaust fans, poor waterproofing
• Failure to maintain — blocked gutters, broken windows, deferred maintenance that allows water ingress
• Pre-existing conditions — mould that was present before the tenant moved in

In NSW, the Residential Tenancies Act 2010 requires landlords to provide premises that are "reasonably clean" and "fit for habitation." Mould caused by building defects clearly falls under this obligation.

Tenant responsibilities

Tenants may be responsible when mould results from:

• Failing to ventilate — never opening windows, not using exhaust fans
• Excessive moisture generation — drying large amounts of laundry indoors without ventilation
• Not reporting leaks — if a tenant notices a leak and doesn't report it promptly, the resulting mould damage may become their responsibility
• Blocking ventilation — covering vents or exhaust fans

However, tenants are not responsible for mould caused by poor building design, even if their lifestyle contributes to moisture levels. If a bathroom has no exhaust fan and no window, the landlord can't blame the tenant for shower moisture.

The grey area

Most mould disputes fall into a grey area. The building may have marginal ventilation, and the tenant may have habits that increase moisture. In these cases:

• The landlord must fix the root cause (ventilation, leaks, building defects)
• The tenant must cooperate with reasonable ventilation practices
• Both parties benefit from professional assessment to determine the actual cause

A professional mould test provides objective evidence that can resolve disputes before they escalate to tribunal.

What to do as a tenant

Step 1: Document everything. Take dated photos and videos of all mould growth. Note the location, extent, and any associated issues (peeling paint, water stains, condensation).

Step 2: Report it in writing. Email your property manager or landlord with photos attached. Keep a copy. In NSW, you can use the standard repair request form.

Step 3: Request urgent repairs. Under the Residential Tenancies Act, mould that affects health is considered an urgent repair. The landlord has 14 days for non-urgent repairs, but health-related issues should be addressed sooner.

Step 4: Follow up. If the landlord doesn't respond within a reasonable timeframe, you can:

• Apply to NSW Fair Trading for a repair order
• Contact the NSW Civil and Administrative Tribunal (NCAT) for a hearing
• Arrange repairs yourself (up to $1,000 for urgent repairs) and deduct from rent — but only as a last resort and only after following the proper process

Step 5: Get professional testing. If there's a dispute about the cause, professional mould testing provides objective evidence of the species, concentration, and likely source.

What to do as a landlord

Step 1: Respond promptly. Ignoring mould complaints creates liability. Acknowledge the report and arrange inspection within days, not weeks.

Step 2: Identify the cause. Don't assume the tenant caused it. Arrange a professional assessment to determine whether the mould stems from building issues or lifestyle factors.

Step 3: Fix the root cause. Painting over mould is not a fix — it returns within weeks. Address the moisture source: repair leaks, install or upgrade exhaust fans, improve ventilation.

Step 4: Remediate properly. For anything beyond a small surface patch, use professional remediation. This protects you legally (you can demonstrate you took appropriate action) and ensures the problem is actually resolved. Our surface mould removal service includes documentation suitable for compliance records.

Step 5: Document the work. Keep records of all inspections, quotes, and remediation work. This protects you in any future dispute.

If you manage multiple properties, our property manager mould guide covers best practices for portfolio-wide mould management.

Common misconceptions

"Just bleach it" — Bleach kills surface mould but doesn't address the root cause. The mould returns, and repeated bleach use damages surfaces. This is not adequate remediation. See our comparison of SAN-AIR vs chemical treatments.

"Open a window and it'll go away" — Ventilation helps prevent mould, but it won't eliminate an established colony. Once mould is growing in porous materials (plasterboard, grout, timber), it needs proper treatment.

"It's just cosmetic" — Mould is a health hazard, not a cosmetic issue. It produces allergens and, in some species, mycotoxins. Courts consistently treat mould as a habitability issue. Learn more about signs of toxic mould.

"The tenant should pay for it" — Only if the tenant demonstrably caused the moisture problem. If the building has inadequate ventilation or structural water ingress, the cost falls on the landlord regardless of tenant behaviour.

Strata properties — an extra layer

If the rental is in a strata building, responsibility may also involve the body corporate. Common area issues — shared ventilation systems, building envelope defects, stormwater drainage — fall under the owners corporation, not the individual landlord. Our guide on strata mould problems explains how body corporate obligations work.

Can you claim mould remediation on insurance?

Sometimes. Landlord insurance typically covers mould caused by sudden events (burst pipes, storm damage) but excludes gradual deterioration or maintenance failures. Tenants' contents insurance may cover damaged belongings but not the remediation itself. For the full picture, see our guide on mould insurance claims in Australia.

Frequently asked questions

Can a tenant withhold rent because of mould? Not in NSW. Tenants cannot stop paying rent, even if repairs are overdue. The correct process is to apply to NCAT for a rent reduction order. Withholding rent can result in termination proceedings against the tenant.

How long does a landlord have to fix mould? For urgent repairs (mould affecting health), the landlord should act immediately. For non-urgent repairs, NSW law allows 14 days. If neither deadline is met, the tenant can escalate to Fair Trading or NCAT.

What if mould appears within weeks of moving in? This strongly suggests a pre-existing condition or building defect. Document the mould immediately and notify the landlord in writing. Condition reports from the start of the tenancy are key evidence.

Does the landlord have to pay for mould testing? There's no legal requirement for who pays, but if the landlord disputes the tenant's claim, independent testing resolves the issue. In practice, the party requesting the test usually pays — but NCAT can order reimbursement if the other party is found responsible.

Can a tenant break their lease because of mould? If the property is deemed uninhabitable and the landlord refuses to remediate, NCAT can terminate the lease. This is a last resort and requires evidence that the mould makes the property unfit for living.

When to get help

Whether you're a tenant or landlord, professional assessment cuts through the blame game. Testing identifies the mould species, the moisture source, and the appropriate remediation method.

At Pureairo, we provide independent assessments for both tenants and landlords across Sydney and the Eastern Suburbs. Our reports are detailed enough for tribunal submissions and insurance claims, and our remediation uses 100% natural SAN-AIR technology — no harsh chemicals in occupied properties.