Stay above the Mould and Dew Points

Introduction: The concepts of mould and dew points are critical in understanding and managing moisture within buildings to prevent dampness and mould growth. Staying above these points is a strategic approach to maintaining a healthy and comfortable indoor environment.


  1. Mould Point: The mould point refers to the temperature at which mould begins to grow on surfaces. This typically occurs when there is excessive moisture or humidity in the air, coupled with a conducive temperature for mould spores to thrive.
  2. Dew Point: The dew point is the temperature at which the air can no longer hold all its water vapour, and some of the water vapour condenses into liquid water. When the temperature drops to the dew point, condensation occurs, which can lead to dampness on surfaces.

Strategies to Stay Above the Mould and Dew Points:

  1. Effective Ventilation:
    • Ensuring proper ventilation helps in reducing indoor humidity, thus raising the mould and dew points.
    • Consider installing extractor fans in bathrooms and kitchens where moisture is generated.
  2. Insulation:
    • Well-insulated walls and roofs help in maintaining higher indoor temperatures, thus staying above the mould and dew points.
    • Ensure insulation materials are vapour-permeable to allow moisture to escape.
  3. Heating:
    • Maintain a steady indoor temperature to keep the interior above the mould and dew point, especially during colder months.
  4. Dehumidification:
  5. Regular Maintenance:
    • Regularly check and repair any leaks in the roof, walls, or plumbing to prevent excess moisture.
    • Ensure rainwater goods are in good condition to direct water away from the building.
  6. Monitoring:
    • Utilize hygrometers to monitor indoor humidity levels and thermometers to check temperatures to ensure they stay above the mould and dew points.
  7. Educating Occupants:
    • Educate building occupants on the importance of maintaining a dry and well-ventilated environment to prevent mould growth and condensation.

Best Solutions:

  1. Continuous Flow Bathroom Extractor Fan:
    • Models like the Brookvent Airstream DMEV 100 HT help in maintaining lower humidity levels in bathrooms, reducing the likelihood of hitting the mould and dew points.
  2. Vapour-Permeable Insulation:
    • Materials like wood fibre or SpaceTherm insulation allow walls to breathe, preventing interstitial condensation.
  3. Regular Professional Assessments:
    • Engage professionals to assess and ensure the building is adequately ventilated, insulated, and maintained to stay above the mould and dew points.

By adopting a combination of these strategies and solutions, it’s possible to create a living or working environment that stays comfortably above the mould and dew points, promoting health, comfort, and structural longevity.

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