Winter Mould in Strata Properties: The Hidden Insurance Risk Many Owners Overlook
- Declan Robinson
- Jun 11
- 5 min read
As winter settles in across Australia, increased rainfall, cooler temperatures, and reduced ventilation create ideal conditions for mould growth within strata buildings. In NSW and QLD, 39% and 26% of regions respectively have a high prevalence of mould in rental homes, with prolonged wet weather, lower temperatures, and ongoing moisture exposure continuing to contribute to the problem.
While mould is often viewed as a maintenance issue, it can quickly become a far more complex problem. Beyond the potential health impacts and property damage, mould frequently sits at the centre of insurance disputes involving water ingress, maintenance obligations, and questions of responsibility between lot owners and owners corporations.
For strata properties, the risks are often amplified. Shared infrastructure, ageing building components, roof cavities, plumbing systems, and common property defects can allow moisture issues to spread beyond a single lot, affecting multiple residents and creating significant remediation costs.
Understanding how mould develops, how insurers assess mould-related damage, and what preventative steps can be taken before winter intensifies is becoming increasingly important for strata managers, owners corporations, and property owners alike.
Why Winter Creates Higher Mould Risks for Strata Properties
Mould requires three key conditions to develop:
Moisture
Suitable temperatures
Limited airflow
Winter naturally provides all three.
Periods of sustained rainfall increase the likelihood of roof leaks, overflowing gutters, plumbing failures, and water ingress. At the same time, occupants spend more time indoors, windows remain closed, and heating systems are used more frequently, reducing natural ventilation throughout apartments and common areas.
Everyday activities such as showering, cooking, drying clothes indoors, and even normal occupancy generate moisture. When that moisture becomes trapped, condensation can form on walls, ceilings, windows, and within concealed building cavities.
In strata properties, several factors can increase vulnerability, including:
Shared walls and services
Roof cavities and common property infrastructure
Ageing waterproofing systems
Poorly ventilated common areas
Undetected plumbing leaks
Buildings with limited natural sunlight
Understanding the winter mould risks in strata properties, and the preventative measures that can minimise mould-related issues, is an important part of preventing building damage and avoiding costly remediation works.
The Insurance Dilemma: Is Mould Covered?
One of the most common misconceptions surrounding mould is that insurance will automatically respond to the damage.
In reality, mould claims can be among the most disputed property insurance matters.
Most insurers differentiate between:
Sudden and Accidental Damage, and;
Gradual Deterioration and Maintenance Issues
Sudden and Accidental Damage
Examples may include:
Storm damage
Burst pipes
Accidental escape of water
Severe weather events
Gradual Deterioration or Maintenance Issues
Examples may include:
Long-term leaks
Condensation
Poor ventilation
Deferred maintenance
Ongoing moisture problems
In NSW and across Australia, standard building and contents policies generally do not cover mould that develops due to maintenance issues, inadequate ventilation, or gradual deterioration, where the mould is the only damage present.
However, coverage may be available where mould is directly linked to an insured event, such as storm damage or a burst pipe.
The challenge often lies in determining the true cause of the moisture that allowed the mould to develop.
The Role of the Reasonable Precautions Clause
Many property insurance policies contain what is commonly referred to as a reasonable precautions clause.
While wording varies between insurers, the intent is generally consistent: policyholders are expected to take reasonable steps to maintain their property and prevent avoidable damage.
From an insurer's perspective, mould can sometimes indicate that an underlying issue existed for an extended period before action was taken.
If evidence suggests that roof leaks, plumbing defects, drainage issues, or ventilation problems were known but not addressed, insurers may rely on maintenance-related exclusions or reasonable precautions when assessing the claim.
As a result, the insurer's investigation frequently focuses less on the mould itself and more on whether the underlying moisture source should reasonably have been identified and rectified earlier.
Who Is Responsible for Mould in a Strata Property?
At Pharos Loss Management, we often see disputes arise over responsibility for mould in strata schemes, making it a highly contentious issue within strata properties.
In most cases, liability depends on:
Where the mould is located
What caused the moisture intrusion
Whether common property is involved
The applicable strata legislation and by-laws
For example, if mould develops due to a leaking roof or common property pipe, responsibility may rest with the owners corporation.
Conversely, mould resulting from internal plumbing defects, poor ventilation practices, or issues contained entirely within a lot may become the responsibility of the individual owner.
Determining the source of moisture is often the most important step in assessing both liability and insurance response.
A Winter Mould Prevention Checklist for Strata Properties
While mould can be costly to remediate, many outbreaks can be prevented through proactive winter maintenance. Identifying moisture sources early and addressing building defects before they escalate can significantly reduce both remediation costs and the likelihood of insurance disputes.
Roof leaks are one of the most common sources of moisture intrusion in strata buildings during winter. Regular inspections should focus on roofing materials, flashing, gutters, downpipes, and external building penetrations to identify potential pathways for water ingress before prolonged rainfall occurs.
Monitor Plumbing and Drainage Systems
Undetected plumbing leaks and poorly functioning drainage systems can create ideal conditions for mould growth. Common property plumbing, stormwater infrastructure, and basement drainage systems should be inspected regularly, particularly in older buildings where deterioration may not be immediately visible.
Investigate Dampness and Water Staining Early
Water stains, discoloured walls, musty odours, and visible condensation are often early indicators of a developing moisture problem. Prompt investigation can help identify the source before mould spreads into wall cavities, insulation, flooring systems, or neighbouring lots.
Improve Ventilation in High-Moisture Areas
Bathrooms, laundries, kitchens, and basement areas are particularly susceptible to excess humidity during winter. Ensuring exhaust fans are operational and ventilation systems are functioning effectively can help reduce condensation and minimise the conditions mould requires to develop.
Review Waterproofing and Known Defects
Existing waterproofing issues, building defects, or unresolved maintenance items should be prioritised before winter conditions intensify. Delaying repairs may not only increase the extent of mould damage but can also create challenges if insurers later argue that reasonable maintenance steps were not taken.
Maintain Comprehensive Records
From an insurance perspective, documentation can be just as important as maintenance itself. Inspection reports, contractor invoices, maintenance logs, photographs, and repair records can assist in demonstrating that reasonable precautions were taken to prevent damage and may prove valuable if a claim is later disputed.
Preventative maintenance not only reduces mould risk but can also strengthen a policyholder's position if an insurance claim later arises.
Navigating Complex Property Damage Claims
Mould-related claims frequently involve complex questions regarding causation, maintenance obligations, policy interpretation, and responsibility between multiple parties.
In many cases, the key issue is not whether mould exists, but why it developed and whether the resulting damage should be covered under the policy.
At Pharos Loss Management, we assist policyholders navigating complex property damage claims involving water ingress, storm damage, moisture-related deterioration, and insurance coverage disputes.
Where insurers challenge causation or seek to rely on maintenance-related exclusions, independent technical assessment and strategic claims preparation can play an important role in protecting policyholder entitlements.
If you're facing a mould-related insurance issue, contact our team for a confidential discussion about your options.
Pharos Loss Management
+61 478 087 092
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