Mould disputes are now one of the most common sources of conflict between landlords and tenants in Australia. Having provided expert evidence in dozens of tenancy tribunal matters over my career, I can tell you that the outcome almost always hinges on two things: who caused the moisture, and what evidence exists to prove it. This guide breaks down the legal framework governing mould in rental properties across every Australian state and territory.

The Fundamental Legal Principle

Before diving into state-specific legislation, it is important to understand the principle that underpins every residential tenancy law in Australia: a landlord must provide premises that are reasonably clean, in a reasonable state of repair, and fit for habitation. This obligation exists at the start of the tenancy and continues throughout its duration.

Mould challenges this principle directly. A property with significant mould growth may not be fit for habitation. But determining responsibility requires understanding whether the mould results from a structural or maintenance deficiency (the landlord’s problem) or from tenant behaviour (the tenant’s problem). In my experience assessing over 5,000 properties, the answer is frequently a combination of both — which is precisely why these disputes become so contentious.

Let me walk through each jurisdiction’s framework.

New South Wales

Residential Tenancies Act 2010 (NSW)

Under the NSW Act, landlords must provide and maintain the premises in a reasonable state of repair, having regard to the age of, rent payable for, and prospective life of the premises (s 63). The NSW Civil and Administrative Tribunal (NCAT) has consistently held that persistent mould caused by building defects — substandard waterproofing, inadequate ventilation systems, rising damp, or roof leaks — is a breach of the landlord’s repair obligations.

Tenants in NSW must notify the landlord of the need for repair (s 65) and must not intentionally or negligently cause or permit damage. Importantly, a tenant who fails to use provided exhaust fans or who blocks ventilation may be found to have contributed to mould growth. However, NCAT has repeatedly clarified that a tenant is not required to open windows in all weather conditions to compensate for a building’s inherent ventilation deficiencies.

The breach notice process under the NSW Act requires the tenant to give the landlord written notice specifying the breach and allowing 14 days for non-urgent repairs. If the landlord fails to act, the tenant can apply to NCAT for repair orders under s 187, compensation under s 187(3), or rent reduction.

Victoria

Residential Tenancies Act 1997 (VIC)

Victoria’s legislation was significantly amended in 2021, introducing minimum rental standards that explicitly address ventilation. Under the Residential Tenancies (Rooming House Standards) Regulations 2012 and subsequent amendments, rental properties must now have functioning ventilation in all wet areas, including exhaust fans in bathrooms and rangehoods or exhaust fans in kitchens.

The Victorian Civil and Administrative Tribunal (VCAT) has been particularly active in mould matters. In several landmark decisions, VCAT has awarded tenants compensation exceeding $10,000 for health impacts caused by landlord negligence in addressing mould. The tribunal consistently emphasises that where a building lacks adequate ventilation by design, the landlord cannot shift blame to tenants for not ventilating sufficiently.

Victoria’s urgent repair provisions (s 72) cover any fault or damage that makes the premises unsafe or insecure. While mould itself is not explicitly listed, a burst water pipe or serious roof leak causing mould would qualify. If a landlord fails to arrange urgent repairs within 24 hours of notification, the tenant may arrange the repair themselves (up to $2,500 without tribunal approval) and seek reimbursement.

Queensland

Residential Tenancies and Rooming Accommodation Act 2008 (QLD)

Queensland’s framework is particularly relevant given the state’s subtropical climate, where mould growth is accelerated by high humidity. Under the QLD Act, the lessor must maintain the premises in good repair (s 185) and ensure the premises are fit for the tenant to live in (s 185(1)).

The Queensland Civil and Administrative Tribunal (QCAT) considers the climate context when assessing mould disputes. In tropical and subtropical regions, some degree of mould management is expected from tenants — regular cleaning, use of exhaust fans, and adequate ventilation. However, QCAT has consistently held that where a property’s design is fundamentally unsuited to the climate (insufficient cross-ventilation, no exhaust fans, poor subfloor ventilation), the landlord cannot expect tenants to overcome these structural shortcomings through behaviour alone.

Breach notices in Queensland require 7 days for urgent matters and a reasonable period for non-urgent repairs. Tenants can apply for a QCAT order if the breach is not remedied within the notice period.

Western Australia

Residential Tenancies Act 1987 (WA)

WA’s Act requires the lessor to provide and maintain the premises in a reasonable state of cleanliness and repair (s 42). The Magistrates Court of Western Australia hears tenancy disputes, and decisions have established that persistent mould caused by building defects constitutes a breach of the lessor’s obligations.

Western Australia’s climate varies enormously — from the tropical north to the temperate southwest — and tribunals consider local conditions when assessing blame. In Perth’s winter months, condensation mould is extremely common, and the question often becomes whether the building provides adequate ventilation for the climatic conditions it was built in.

South Australia

Residential Tenancies Act 1995 (SA)

South Australia’s legislation requires landlords to provide premises that are in a reasonable state of cleanliness and repair at the start of the tenancy (s 67) and to maintain them throughout (s 68). The South Australian Civil and Administrative Tribunal (SACAT) has jurisdiction over tenancy disputes.

SA’s relatively dry climate means mould issues typically indicate a more serious underlying problem — plumbing leaks, rising damp, or building envelope failures. SACAT tends to view persistent mould as strong evidence of a maintenance failure requiring landlord action. Breach notices must allow a reasonable time for repair, typically 7–14 days depending on the nature and urgency of the issue.

Tasmania

Residential Tenancy Act 1997 (TAS)

Tasmania’s older housing stock and cold, damp climate make mould one of the most prevalent rental issues in the state. The Act requires landlords to ensure the premises are in a reasonable state of repair and are fit for habitation. The Residential Tenancy Commissioner handles disputes, with the Magistrates Court serving as the appeal body.

Tasmania’s climate presents unique challenges. Many older rental properties lack insulation, have single-glazed windows, and were built without modern ventilation standards. Condensation on cold surfaces is inevitable in these buildings during winter, regardless of tenant behaviour. The Commissioner has recognised this reality, often finding in favour of tenants where the building fabric itself creates conditions conducive to mould growth.

Australian Capital Territory

Residential Tenancies Act 1997 (ACT)

The ACT introduced minimum housing standards in 2023, including requirements for adequate ventilation, insulation, and moisture management. These standards have significantly strengthened tenants’ positions in mould disputes. Under the Act, landlords must ensure the premises meet minimum standards (s 71B) and maintain them in a reasonable state of repair (s 71).

The ACT Civil and Administrative Tribunal (ACAT) has been proactive in applying these new standards to mould matters. Where a property does not meet minimum ventilation or insulation standards, the landlord’s position in defending a mould complaint is substantially weakened.

Northern Territory

Residential Tenancies Act 1999 (NT)

The Northern Territory’s tropical climate makes mould management a constant consideration. The Act requires landlords to provide and maintain premises in a reasonable state of repair and fit for habitation (s 49). The Northern Territory Civil and Administrative Tribunal (NTCAT) considers the tropical climate context — some mould exposure is considered normal in Darwin and the Top End, but excessive growth due to building defects remains the landlord’s responsibility.

In the NT, air conditioning is often considered an essential service given the climate. Failure to maintain functioning air conditioning — which is the primary moisture management tool in tropical housing — is treated seriously by the tribunal. A tenant whose air conditioning has failed and who subsequently develops mould has a strong case for landlord responsibility.

Common Threads Across All Jurisdictions

Despite the different legislative frameworks, several principles apply consistently across Australia:

• Structural causes are the landlord’s responsibility. If mould results from roof leaks, plumbing failures, rising damp, inadequate ventilation design, or poor building envelope performance, the landlord must rectify both the cause and the resulting mould damage.
• Tenants must report issues promptly. Every jurisdiction requires tenants to notify the landlord of repair needs. Failure to report a leak or mould growth promptly may reduce a tenant’s entitlement to compensation.
• Tenants must not cause or exacerbate mould. Drying clothes indoors without ventilation, blocking exhaust fans, or failing to use provided ventilation can shift some or all responsibility to the tenant.
• Rent cannot be unilaterally withheld. In no jurisdiction may a tenant simply stop paying rent due to mould. The correct process is always through the relevant tribunal.
• Evidence is everything. Photographs, written communications, breach notices, and professional assessment reports form the backbone of any tribunal case.

The Role of Independent Testing in Tenancy Disputes

In my experience providing expert mould assessment for tribunal matters, independent testing evidence is often the deciding factor. Here is what I mean by that.

When a tenant says “there’s mould everywhere” and a landlord says “it’s condensation from poor ventilation habits,” the tribunal needs objective data to determine who is correct. An independent assessment provides:

• Moisture source identification — thermal imaging, moisture mapping, and hygrometer readings can determine whether moisture is coming from within the building envelope (landlord’s issue) or from indoor activities (tenant’s issue)
• Mould species identification — laboratory analysis through independent NATA-accredited laboratories can identify whether the species present indicate chronic moisture (structural problem) or recent surface condensation
• Extent quantification — air sampling and surface sampling provide objective data on the severity of contamination, replacing subjective assessments with measurable evidence
• Causation analysis — a qualified assessor can often determine the primary moisture source through systematic investigation

Bond Claims Related to Mould

Mould-related bond disputes are increasingly common. A landlord seeking to claim bond for mould damage at the end of a tenancy must demonstrate that the mould was caused by the tenant, not by pre-existing conditions or building defects. This is where the ingoing condition report becomes critical.

I strongly recommend that both landlords and tenants arrange independent mould testing at the commencement of a tenancy where there is any history of mould or where the property’s age, construction type, or location suggests mould risk. This baseline assessment provides irrefutable evidence of the property’s condition at the start — protecting the landlord from false claims of pre-existing mould and protecting the tenant from being blamed for mould that was already present.

Rent Reduction and Compensation

Every state and territory tribunal has the power to order rent reduction where mould diminishes the tenant’s quiet enjoyment of the property. The amount varies considerably, but tribunal decisions suggest:

• Minor mould in one room: 5–15% rent reduction for the affected period
• Moderate mould affecting multiple rooms: 15–30% rent reduction
• Severe mould rendering rooms uninhabitable: 30–50% or more
• Health impacts with medical evidence: Additional compensation beyond rent reduction

These are indicative ranges based on published tribunal decisions across multiple jurisdictions. Every case is assessed on its individual facts.

When Can a Lease Be Terminated?

Lease termination for mould is the most serious outcome and is reserved for the most severe cases. Tribunals will generally order termination only where:

• The property is genuinely uninhabitable due to mould contamination
• The landlord has been given reasonable notice and opportunity to repair
• The mould issue is not primarily caused by tenant behaviour
• Remediation would be so extensive as to require the tenant to vacate regardless

In these circumstances, the tribunal typically orders termination without break-lease fees and may order compensation for the tenant’s relocation costs.

Practical Recommendations

For Landlords

• Ensure all wet areas have functioning exhaust fans before a new tenancy begins
• Address any reported leaks or moisture issues immediately — delay strengthens the tenant’s tribunal case
• Consider independent mould testing at the start and end of tenancies for high-risk properties
• Document all maintenance and repairs with dates, invoices, and photographs
• Review your insurance coverage for mould-related claims

For Tenants

• Report any mould or moisture issues in writing immediately — email creates a dated record
• Use exhaust fans and maintain reasonable ventilation — this protects your position
• Photograph mould growth with dates and keep copies of all correspondence
• Follow the breach notice process in your state before applying to the tribunal
• Consider arranging independent testing if the dispute escalates — the cost is modest compared to the potential outcomes at tribunal

If you are involved in a mould-related tenancy dispute — whether as landlord or tenant — contact Test Australia for independent, expert assessment. Our reports are designed to meet tribunal evidence requirements and provide the objective data that decision-makers need.