Mould in a rental property is more than an aesthetic problem. It’s a health hazard that can cause respiratory issues, allergic reactions, and aggravate asthma. Black mould in particular — Stachybotrys chartarum — has been linked to serious health problems with prolonged exposure. If your rental has mould, you need to act quickly and strategically.

The good news: in most cases, mould is the landlord’s problem to fix. The bad news: getting them to actually deal with it can be a battle. Here’s how to fight it.

Is It the Landlord’s Problem or Yours?

This is the first question that determines everything. Mould caused by structural issues — poor ventilation, water leaks, rising damp, inadequate weatherproofing — is the landlord’s responsibility. These are defects in the property itself, and the landlord has a legal obligation to maintain the property in a habitable condition.

Mould caused by tenant behaviour — never opening windows, drying clothes inside without ventilation, blocking vents — can potentially be attributed to the tenant. Landlords and property managers love to claim that all mould is caused by “lifestyle choices.” Don’t accept this at face value.

The reality is that most mould in Australian rentals is caused by structural issues, not tenant behaviour. Older properties often have inadequate ventilation, poor insulation, and drainage problems that create the damp conditions mould needs to grow. Even tenants who ventilate diligently can’t prevent mould when the building itself is the problem.

How do you tell the difference? Mould that appears in areas with known structural issues (around window frames with broken seals, on walls adjacent to leaking pipes, in bathrooms without exhaust fans) is almost certainly a structural problem. Mould that only appears behind furniture you’ve pushed flush against an external wall might be a ventilation issue — but even then, a properly built wall shouldn’t produce condensation just because there’s furniture near it.

Step 1: Document Everything

Before you do anything else, document the mould thoroughly. Take photos showing the location, extent, and severity. Include wide shots of the room and close-ups of affected areas. Note the date of discovery and any conditions that seem relevant (recent heavy rain, known plumbing issues, lack of exhaust fans).

If the mould is causing health problems for you or your family, see a doctor and get it documented. A medical report linking your symptoms to mould exposure is powerful evidence if you end up at tribunal.

Check your ingoing condition report. Was mould noted when you moved in? If so, it’s clearly a pre-existing issue that the landlord failed to address. If the report said the property was mould-free and mould has since appeared, that’s evidence of a developing structural problem.

Step 2: Report It Formally

Don’t just mention it to the property manager in passing. Put it in writing. Use the formal repair request process required by your state’s tenancy legislation. In most states, this means completing a specific form and sending it by mail, email, or through the property manager’s portal.

Your repair request should include:

• A clear description of the mould (location, size of affected area, type if identifiable)
• Photos attached or referenced
• Any health impacts you’ve experienced
• A request that the cause be identified and remediated, not just the surface mould cleaned

This last point is critical. Landlords who respond to mould reports by sending someone to wipe the surfaces with bleach aren’t fixing anything. The mould will return within weeks because the underlying cause — damp conditions from structural defects — hasn’t been addressed. Proper remediation involves identifying the moisture source, fixing it, and then treating the affected areas.

The Tenants’ Union of NSW and equivalent bodies in other states provide template repair request letters specifically for mould issues. Use them.

Step 3: Understand the Timeframes

In most states, landlords must respond to repair requests within specific timeframes. Urgent repairs (which can include mould causing health issues) typically require a response within 24-48 hours. Non-urgent repairs usually have a 14-28 day response window.

If the landlord doesn’t respond within the required timeframe, you can escalate. The process varies by state but generally involves notifying the relevant tribunal and potentially arranging repairs yourself and seeking reimbursement.

In Victoria, tenants can issue a breach notice if repairs aren’t completed within 14 days. In NSW, they can apply to the tribunal for a repair order. In Queensland, the RTA provides conciliation services before matters go to tribunal.

Step 4: Know Your Rights Around Rent Reduction

If mould makes part of your property unusable or significantly impacts your ability to enjoy the premises, you may be entitled to a rent reduction. This applies particularly when bedrooms, living areas, or bathrooms are affected to the point where using them poses health risks.

You can’t just unilaterally reduce your rent — that creates grounds for the landlord to claim you’re in arrears. Instead, apply to the tribunal for a rent reduction order. Document the impact: which rooms are affected, how your use of the property has been restricted, and for how long the problem has persisted without resolution.

Tribunals take mould-related rent reduction claims seriously, especially when there’s medical evidence of health impacts and documentation showing the landlord failed to respond to repair requests.

Step 5: The Nuclear Option — Termination for Breach

If the mould is severe, the landlord won’t fix it, and it’s affecting your health, you may have grounds to terminate the lease early without penalty on the basis that the landlord has breached their obligation to provide habitable premises.

This is a significant step and should be a last resort. The process involves issuing a breach notice to the landlord, allowing them a period to remedy the breach (typically 14 days), and then applying to the tribunal for termination if they don’t.

You’ll need strong evidence: documented mould, formal repair requests, evidence of the landlord’s failure to respond, and ideally medical evidence of health impacts. But tribunals do grant these terminations, particularly when the mould is extensive and the landlord has been unresponsive.

Prevention and Practical Tips

While fighting the landlord, there are some things you can do to limit mould growth:

• Open windows daily, even briefly in winter, to allow moisture to escape
• Use exhaust fans in bathrooms and kitchens (and report them if they’re broken — that’s a repair request)
• Avoid drying clothes indoors without ventilation
• Keep furniture slightly away from external walls to allow air circulation
• Wipe condensation from windows regularly
• Use a dehumidifier if the property is chronically damp

These measures don’t fix structural problems, but they can slow mould growth while you pursue the landlord for proper repairs. And documenting that you took these steps undermines any argument that your behaviour caused the mould.

Your health matters more than your deposit. Don’t ignore mould to avoid conflict with your landlord.