The short answer
Produce less moisture, get what you produce out of the house, and keep the surfaces warmer. In that order, because the third one costs money and the first two do not.
- Produce less. Lids on pans. Dry washing outside or in one closed room. Vent the tumble dryer properly.
- Get it out. Extractor fan on during a shower and for fifteen minutes afterwards. Window open a crack while cooking. Trickle vents unblocked.
- Keep surfaces warmer. Low background heat across the day beats short blasts of high heat, because it is the cold surface that condenses, not the warm air.
- Leave a gap behind furniture on external walls so air can move.
- Open two windows on opposite sides for ten minutes each morning. It changes the air without cooling the structure of the house.
What will ruin it
Blocking trickle vents or permanently closing the bathroom window because of the draught is how most serious condensation problems start.
Why it works
Warm air holds more water vapour than cold air. When it touches a cold surface it cools, it can no longer hold what it is carrying, and the difference appears as liquid water on the glass or the wall.
Household chemicals can be dangerous in combination. Never mix them, keep the room ventilated, and test anything on a hidden patch first. Full disclaimer.
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