Condensation on the inside
Condensation on the inside of the pane and/or the frame and sash is a completely natural phenomenon and not something caused by a defect in your VELUX roof window.
Why does condensation occur?
Condensation occurs when the level of humidity in the building is too high. Condensation then forms on relatively cold surfaces, such as a window pane. The immediate solution is to ventilate the room - preferably a couple of times a day for about 5 minutes.
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