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

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.

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

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.

"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.

"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.

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. 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.