Condensate is a natural phenomenon and not a product issue. It is a sign of a high level of humidity which means that increased ventilation is required. An average family of four generates approximately 10-15 liters of water vapor every day through cooking, showering, drying clothes and evaporation from the skin. The water vapor does not disappear, but needs to be vented to avoid it from settling in the building. To actively reduce the amount of vapor ventilation is needed. Even during autumn and winter when all doors and windows are kept closed, the best way to lead the water vapor out is to open at least two windows for cross ventilation 5-10 min. 4 times a day.

Even the modern, highly insulating way of constructing buildings facilitates this phenomenon. With windows and doors closed, new buildings are almost completely airtight. Which is good for the energy consumption but not ideal for the indoor climate. There is no longer any air exchange through joints and crevices. Lack of air exchange combine with high humidity can result in mold formation, damage to the house and over time cause diseases of the inhabitants. So ventilation must be done differently in new and renovated buildings compared to older buildings.

Condensation is usually more noticeable on roof windows and flat roof windows because warm, moist air rises to the ceiling. The problem, however, usually isn't the roof window. It’s the excess moisture in the room. Condensation is more prevalent in new homes. After a few years, new homes tend to dry out and have less moisture problems.

Condensation is more prevalent in new homes. After a few years, new homes tend to dry out and have less moisture problems. Eliminating excess moisture by using a dehumidifier and providing adequate ventilation and air circulation will go a long way in preventing condensation. Installing roofing underlay between the roof window frame and roofing material will help prevent condensation on the cladding.

For more information and tips on condensation, please click here.

Flat roof windows

When condensation is present between the window and the top cover of a flat roof window, it can suggest that excess moisture was present during the installation of the top cover. To resolve this, you will need to remove the top cover of your flat roof window, and dry out any moisture internally. Once this has been dried off, place the top cover back down. There will always been a small amount of moisture between the window and top cover, however the airflow between the window and top cover should be sufficient to allow for the small amount of moisture to condensate and evaporate without noticing.

What should I do when I have condensation on my window?