Waking up to windows running with water is a familiar sight in Yorkshire from October onwards. Condensation is not always a problem, but where it forms tells you a lot about your home and your glazing.
Condensation on the inside
Warm, moist air inside the house meets cold glass and turns back into water. Cooking, showers, drying washing indoors and simply breathing all add moisture. It is most common in bedrooms, bathrooms and kitchens, and on older or single-glazed windows.
How to reduce it
- Open trickle vents on your windows and leave them open.
- Use extractor fans when cooking and showering, and run them for a while afterwards.
- Dry washing outside or in a ventilated room where possible.
- Keep heating steady rather than on and off, so surfaces stay warmer.
- Wipe windows and sills dry in the morning to stop mould starting on seals.
Condensation on the outside
Dew on the outside of the glass on a clear, cool morning is actually a good sign. Modern double and triple glazing keeps heat in so well that the outer pane stays cold enough for dew to form. It clears as the day warms up.
It can, however, leave marks as it dries if the glass is dirty, because the moisture mixes with dust and pollen. Clean glass dries clear, which is one reason windows on a regular round stay looking better through autumn and winter.
Condensation between the panes
If moisture appears between the two panes of a double-glazed unit, the seal has failed. Air and moisture have got into the gap, and the unit will no longer insulate properly. No amount of cleaning will fix this; the sealed unit needs replacing by a glazier, usually without changing the frame.
Our window cleaners often spot failed units during a clean and will let you know, so you can get it sorted before winter.
Conservatories
Conservatories are prone to condensation because they have so much glass. Good ventilation helps, and so does keeping the roof clean: a dirty roof holds moisture and grows algae. See our conservatory cleaning service.
Quick answers
- Is condensation on the outside of windows a bad sign?
- No. External condensation on cool mornings usually means your glazing is insulating well and keeping heat inside.
- What does condensation between the panes mean?
- It usually means the seal on a double-glazed unit has failed. Cleaning will not fix it; the sealed unit needs replacing.
- Can condensation damage window frames?
- Over time, yes. Constant moisture can lead to mould on seals and frames, and rot in timber windows.