Why are my windows wet every morning, and what does that actually mean?
Condensation on glass is almost always a ventilation problem before it is a window problem. The air in the house holds moisture from cooking, washing, drying clothes and breathing, and the coldest surfaces in the room are usually the windows. Reducing the moisture in the air, or removing it before it reaches the glass, is the lasting fix. Replacing windows alone tends to move the condensation somewhere worse.
What it usually looks like
These are the symptoms readers describe most often. None of them alone is diagnostic, but together they build a picture.
- Streaming water on glass every morning in winter
- Damp curtains and wet sills
- Black spotting starting to appear in corners
- Worse in bedrooms than in living rooms
Most common in: Victorian terrace · Edwardian semi-detached · Interwar semi (1920s–1930s) · New-build flat
Before you buy anything
Watch the house respond as you scroll.
These checks are listed in the order we would work through them. The illustration on the left changes with each one, so you can see what each check is actually addressing before deciding whether it is worth doing.
Warm wet air meets the coldest surface in the room overnight, which is almost always the window. By morning it is running.
Buy a cheap hygrometer and read it for a week
Above sixty per cent relative humidity is the threshold where condensation and mould risk start. Knowing the actual number tells you what kind of intervention you need.
Check where moisture is being created
Drying clothes indoors without ventilation can add ten litres of water to the air per week. Moving drying to a vented utility, or using a dehumidifier in the same room, makes a measurable difference.
Confirm the extractor fans actually work
A bathroom extractor that takes ten minutes to clear a steamy mirror is doing very little. Run-on timers and humidistat switches are inexpensive upgrades.
Check the trickle vents on the windows
Many homes have trickle vents that have been taped shut or painted over. Opening them is free and often resolves persistent morning condensation.
Measure surface temperatures in the worst rooms
A cold spot in a corner that sits below the dew point will always condense. Adding insulation to the cold surface is the real fix, not a dehumidifier.
Products that may help
Only consider these once the checks above have been ruled out. A product fitted into the wrong cause is rarely satisfying.
The cheapest answer to condensation on windows every morning is usually the one that addresses the cause rather than the symptom. The list above is in the order we would work through it, because the checks at the top tend to rule out the most expensive mistakes further down.
Run the Home Comfort Score for this room
A two-minute reading gives you a number to compare against after each improvement, so you know what is actually working.