Mould Point:

Mould Point: is like dew point, but calculated working out the temperature where the surface exceeds 85% relative humidity (RH), when mould germination and growth is at risk. The relative humidity increases by approximately 5% RH with every 1°C drop in temperature, thus typically placing the mould point 3°C above the dew point. This concept is critical for comprehending and managing moisture within structures to avert dampness and mould proliferation. Keeping the indoor environment above the mould point is a strategic manoeuvre to uphold a healthy and comfortable indoor ambience.

Refer to the glossary for a deeper understanding of mould and dew points, and the significance they hold in averting damp and mould issues within buildings. The excerpt below elucidates the mould and dew points and offers strategies to stay above these critical temperatures:

The notions of mould and dew points are pivotal in grasping and controlling moisture within edifices to prevent dampness and mould growth. Staying above these points is a strategic method to sustain a healthy and comfortable indoor environment.


  • Mould Point: The mould point delineates the temperature at which mould begins to burgeon on surfaces. This usually transpires when there is excessive moisture or humidity in the air, paired with a conducive temperature for mould spores to flourish.
  • Dew Point: The dew point is the temperature at which the air can no longer retain all its water vapour, leading some of the water vapour to condense into liquid water. When the temperature descends to the dew point, condensation transpires, potentially causing dampness on surfaces.

Strategies to Stay Above the Mould and Dew Points:

  • Effective Ventilation: Proper ventilation aids in diminishing indoor humidity, thus elevating the mould and dew points. Consider installing extractor fans in bathrooms and kitchens where moisture is generated.
  • Insulation: Well-insulated walls and roofs assist in sustaining higher indoor temperatures, thus staying above the mould and dew points. Ensure insulation materials are vapour-permeable to permit moisture escape.
  • Heating: Maintain a consistent indoor temperature to keep the interior above the mould and dew point, especially during the colder months.
  • Dehumidification: Utilise dehumidifiers to lower indoor humidity levels, particularly in damp-prone areas like basements.
  • Regular Maintenance: Routinely 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.
  • Monitoring: Employ hygrometers to monitor indoor humidity levels and thermometers to check temperatures to ensure they stay above the mould and dew points.
  • Educating Occupants: Enlighten building occupants on the importance of maintaining a dry and well-ventilated environment to thwart mould growth and condensation.

Best Solutions:

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

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