Use effective extraction in bathrooms and kitchens, vent moisture outside, maintain steady background ventilation and heating where appropriate, dry clothes responsibly, and improve insulation or thermal bridging at repeatedly cold surfaces.
This guide is written for South Africa, Australia, New Zealand. Always check local codes, product specifications, licences, and site conditions.
Step by step
Confirm it is condensation
Look for morning window moisture, growth in corners or behind furniture, and patterns linked to showers, cooking, drying clothes, or cold weather.
Control moisture at source
Run correctly sized exhaust fans, use lids when cooking, address plumbing leaks, and avoid releasing dryer air indoors.
Improve air and surface temperatures
Allow airflow behind furniture, use background ventilation, reduce draught extremes, and insulate persistently cold surfaces where practical.
Clean and monitor
Use suitable protective equipment and a method appropriate to the surface and extent. Track humidity and recurrence after changes.
Expert tips
- A small humidity monitor can reveal daily patterns.
- Do not paint over active mould.
- Large, recurring, or health-sensitive cases need professional assessment.
Common questions
Is mould always caused by a leak?+
No. Condensation on cold surfaces is common, but plumbing, roof, ground, or envelope leaks must also be ruled out.
Will opening windows solve condensation?+
It can help when outdoor air is drier, but source extraction, heating, insulation, and climate conditions also matter.
Does anti-mould paint fix the problem?+
It may slow surface growth, but it does not remove the moisture source or correct a cold surface.
Sources & further reading
We link to official building-code, government and public-health material where a technical or safety claim needs authoritative context. Local rules and adopted code editions can change.
- World Health OrganizationGuidelines for indoor air quality: dampness and mouldEvidence review and public-health guidance on persistent dampness and microbial growth.↗
- Australian Building Codes BoardNCC Part F8: Condensation managementBuilding-code principles for moisture removal and condensation risk.↗
- New Zealand Building PerformanceControlling moisture and dampGovernment guidance on source control, heating and ventilation.↗
Stop if the work involves structural uncertainty, hazardous materials, heights, live services, gas, serious water damage, or regulated work. Local rules differ—use an appropriately licensed professional where required.