Overview
- Condensation forms when warm, humid air cools to its dew point on cold surfaces such as glass, walls or mirrors.
- Outside droplets often signal efficient double glazing that keeps indoor heat from warming the outer pane, whereas persistent inside moisture points to ventilation or heat-loss issues.
- A practical morning routine—vacuuming droplets with a window vac, cracking windows for fresh air and running a dehumidifier—has been shown to cut window moisture quickly.
- Low‑cost stopgaps such as placing cat litter in a sock on the sill can absorb some moisture, though experts note these are less effective than a dedicated dehumidifier and do not fix root causes.
- Guidance recommends extractor fans, dehumidifiers or, if needed, new windows to curb humidity long term, and warns that trapped moisture can lead to damp, black mould, damaged paint and rotting wood.