Attic dehumidification

Damp problems in the attic

According to an investigation carried out by the Swedish National Board of Housing, about 300,000 buildings in Sweden suffer from mould, mildew odours or high moisture levels that can be directly traced to problems in the attic.

  • Cold attic spaces are at the greatest risk

    84% of these attics are cold attics with natural ventilation.
    There are many things that can cause problems with moisture and mould in the attic:

    • Warm and moist air from the indoor environment enters the cold attic through unsealed areas and condenses.
    • Additional attic insulation means that the attic gets colder  which causes moisture condenses more easily.
    • Changing a heat source also means that there are changes to the air pressure throughout the house. Switching to ground source/district heating means that a chimney that was previously warm is now cold, and there is no longer any “chimney effect”.
    • Built-in construction moisture can also cause humidity and mould in the attic.
    • The ventilation requirement varies from attic to attic as well as during the course of the year. Ventilating an attic too much can also cause problems. If the outdoor air is cold, the air in the attic is cooled and can cause condensation against the cold outer roof. Or, when the temperature of the outer roof falls, for example after a warm day, the cooling and the increased relative humidity can lead to condensation on the inside of the roof.

  • Measures that solve the problem of damp in the attic

    • Seal the attic joists and ventilate the living area, not least the wet areas, to prevent the moisture in the air flowing into the attic area.
    • Install permanent equipment for controlled ventilation in the attic space. This creates a suitable environment for all building materials that prevents mould, rot and other microbial damage.

  • Corroventa's solution:

    Demand controlled ventilation withVentoVindTM

    Corroventa’s VentoVindTM is a system which provides optimised ventilation and thereby minimises moisture-related problems such as mould and rot.
    VentovindTM is a system for demand controlled ventilation, which guarantees that the ventilation only takes place when it benefits the attic space. The supply air system ensures ventilation at the right times, while establishing an impression of the attic that breaks up the travel of moisture from the accommodation.
    • VentoVindTM ensures ventilation of the attic at the right time. The system means that amount of ventilation is precisely enough for the attic requirement, while saving energy.
    • VentoVindTM creates a controlled climate with optimised ventilation without the supply of energy consuming heating.

  • Facts about moisture damage in attics

    • Approx. 9 out of 10 small houses have a cold air, ventilated attic.
    • Studies from Chalmers University of Technology, carried out in West Götaland, have shown that 72% of all small houses with attics have high moisture values and a high occurrence of fungus.
    • In recent years Chalmers University of Technology and the KTH, the Royal Institute of Technology in Stockholm, have conducted several studies that have shown that moisture and mould in attics is a major and growing problem.
    • In a detailed analysis of Swedish real estate (December 2010), the Swedish National Board of Housing notes that the attic is the part of the building’s construction where moisture and mould occur most.
    • Attic damage is rarely covered by standard house insurance, so it is recommended that the attic should be inspected once a year to be able to detect and rectify any damage.