Condensation: what to know
Condensation is most likely when moisture appears on cold surfaces, is worse in colder weather, and follows everyday moisture from showers, cooking, drying clothes or breathing.
What to check first
- Check indoor relative humidity over several days rather than relying on one reading.
- Confirm bathroom and kitchen extraction actually vents outdoors and is working.
- Look for cold surfaces, blocked vents, furniture tight to external walls and rooms that are under-heated.
What not to assume
Do not assume every black mould patch is “just condensation”. Rain penetration, plumbing leaks and hidden defects can also wet surfaces.
Sensible next step
Improve moisture removal and ventilation, maintain reasonable background heat, and investigate persistent localised wetting that does not fit the condensation pattern.
The clues that matter most
Use several clues together rather than treating one mark, smell or meter reading as proof.
Check indoor relative humidity over several days rather than relying on one reading.
Confirm bathroom and kitchen extraction actually vents outdoors and is working.
Look for cold surfaces, blocked vents, furniture tight to external walls and rooms that are under-heated.
Do not assume every black mould patch is “just condensation”. Rain penetration, plumbing leaks and hidden defects can also wet surfaces.
Improve moisture removal and ventilation, maintain reasonable background heat, and investigate persistent localised wetting that does not fit the condensation pattern.
Could it be something else?
These routes help separate common causes that can create similar visible damage.
Useful products for this stage
Only products that support the investigation or an appropriate fix are shown here. An active leak or building defect still needs repairing.
