After a leak or flood, the key questions are where moisture remains and whether the water source has been resolved. Mould can grow on damp materials, including in places that are difficult to see. A dry-looking surface does not establish that the layers beneath it are dry.
What influences mould growth after water damage?
Ongoing water entry
Leaking plumbing, roof defects and condensation can keep materials damp. Repairing the source and dealing with the resulting damage are connected tasks: cleaning a surface does not fix an ongoing moisture problem. The appropriate trade may need to repair the leak while restoration work addresses affected materials.
How long materials remain wet
The EPA recommends drying wet materials promptly, with 24–48 hours used as an important prevention window. This is a reason to act early, not a guarantee that mould will be absent before a deadline or that every material can be dried in that time. Existing growth and the condition of the materials still need assessment.
Materials and hidden moisture
Carpet backing, underlay, timber, plasterboard and other materials can retain moisture. The EPA identifies concealed locations such as wall cavities and the underside of carpets as possible sites of hidden growth. A musty smell can be a reason to investigate, but does not identify the source or extent by itself. See our guide to signs of hidden water damage.
Humidity and drying conditions
Humid air and condensation can contribute to damp conditions. Ventilation, dehumidification and access to wet layers need to suit the building and the damage. Simply making a room cooler or changing its lighting is not a substitute for controlling moisture. Read how structural drying works for an explanation of assessment and monitoring.
Contamination changes the response
Sewage, outside floodwater or an unknown water source needs appropriate assessment. The EPA recommends experienced professional help for damage involving contaminated water. If an air-conditioning or ventilation system is suspected of containing mould, seek advice before running it because it may spread contamination.
Avoid disturbing suspected mould to investigate it. Queensland Health advises against dry brushing mould because it can release spores. If you have health concerns, seek advice from a health professional.
Arrange an assessment and explain what has changed
Tell Reztor when the water damage was first noticed, whether the source is still active, which rooms are affected and whether there is visible growth or a persistent odour. Send photographs only where it is safe to take them.
Explore mould assessment and remediation or water damage restoration, then send the property details and safe photos so the team can discuss the next step.