How do I tell if mould is from condensation?

31st May 2024 | |

To determine if mould in your home is caused by condensation, look for the following signs and conditions:

  1. Location:
    o Windows and Frames: Mould from condensation commonly appears around windows and window frames due to temperature differences between the indoor air and the glass surface.
    o Walls and Ceilings: It often forms on external walls, especially in corners, or ceilings where warm, moist air meets cooler surfaces.
    o Unventilated Areas: Look in places with poor ventilation like bathrooms, kitchens, or behind furniture placed against external walls.
  2. Appearance:
    o Patterns: Mould from condensation typically appears in a uniform pattern, such as patches or streaks, rather than in isolated spots.
    o Type: The mould might appear black, green, or brown and can often be slimy or powdery.
  3.  Environmental Conditions:
    o Humidity Levels: High indoor humidity levels (above 60% and certainly above 70%) are a key indicator. A hygrometer can be used to measure humidity.
    o Temperature Differences: Condensation mould often results from significant temperature differences between indoor air and surfaces, causing moisture to condense on the colder surfaces.
    o Ventilation: Poor ventilation in rooms, especially those with high moisture generation like bathrooms and kitchens, contributes to condensation mould.
  4. Behaviour of Mould Growth:
    o Seasonal: Condensation mould is more common in colder months when indoor air is warmer and more humid compared to the cold exterior, leading to condensation on cold surfaces.
    o Consistency: Mould from condensation tends to grow steadily and consistently in the same areas where moisture collects.
  5. Testing and Inspection:
    o Moisture Meters: Use a moisture meter to check the dampness of walls and surfaces. High readings can indicate condensation issues.
    o Professional Inspection: If unsure, feel free to contact us to determine the cause of mould.

By observing these factors, you can often distinguish if mould is due to condensation. If you identify condensation as the cause, improving ventilation, using dehumidifiers, and insulating cold surfaces can help mitigate the issue.

For any advice on dampness, water damage or building drying with dehumidifiers, please contact us on 020 7760 7660 or