21/09/2026
Ventilating in the rain? Absolutely.
Many wonder whether to ventilate when it's raining. The answer is clear: yes. Even in the rain, outdoor air is drier than stale indoor air. Skipping regular ventilation risks poor air quality and mould.
What matters most:
Cross-ventilation is the most effective method. Several times a day, open windows wide for 6 to 10 minutes. Avoid leaving windows tilted, as this cools the walls and encourages mould.
The ideal indoor humidity is between 30 and 45 %. A hygrometer helps you keep track.
Good to know: All automatic VELUX roof windows come with a rain sensor and close automatically when it starts to rain. Manual centre-pivot windows can easily be upgraded with a motor and rain sensor.