Buying Guide
How to Stop Condensation on Windows in Winter UK
Updated August 2026
Winter condensation is worse than any other time of year. The heating comes on, the windows stay cold, and every surface of glass drips with water. Opening windows isn't practical when it's freezing outside. Here's how to stop winter condensation without living in a cold house — 8 fixes from free to £200.
Quick answer
Our top pick: Deconovo Thermal Curtains
£18–£28 on Amazon
The winter-specific fix that most people miss: thermal curtains (£18-28) raise the glass temperature so condensation can't form. Combined with a dehumidifier set to 50% RH, this eliminates winter condensation completely.
Check Price on Amazon →Why condensation is worse in winter — the science
Air holds water vapour, and how much it can hold depends entirely on temperature. Air at 20°C holds roughly twice as much moisture as air at 10°C. Cool that warm air down and the extra moisture has nowhere to go, so it condenses onto whatever surface did the cooling.
In winter, your window glass is the coldest surface in the room by a wide margin. A single-glazed pane on a 2°C night can sit at 6-8°C while the room air is 19°C. The air touching the glass cools past its dew point within millimetres and the water comes out onto the pane.
Winter makes this worse three ways at once: the glass is colder, we produce more moisture indoors (drying laundry inside, longer showers, more cooking), and we ventilate far less because opening windows is unpleasant. That combination is why October to March is condensation season in the UK.
8 winter condensation fixes, ranked
- Free — purge ventilate for 10 minutes each morning. Open windows wide, close internal doors, then shut up. Moist air out, dry air in, minimal heat lost.
- Free — keep the heating low and steady. A constant 18°C produces far less condensation than a cold house blasted to 22°C for two hours each evening.
- Free — shut bathroom and kitchen doors. Contain the steam at source and extract it there rather than letting it reach cold bedroom glass.
- £6 — absorber strips on the glass. They do not stop condensation, but they stop the run-off rotting your sills.
- £10 — a hygrometer. Target 40-55% RH. Without a reading you are guessing at whether anything you try is working.
- £18-28 — thermal curtains. The winter-specific fix: warmer glass means the dew point is never reached.
- £20-30 — window insulation film. Creates a still air gap over single glazing, raising the inner surface temperature dramatically.
- £95 — an electric dehumidifier with a humidistat. The definitive fix. Hold the room at 50% RH and condensation simply cannot form.
The products we recommend
Deconovo Thermal Blackout Curtains
Triple-weave thermal lining slows the flow of warm room air across the cold pane, and keeps more heat in the room overall. Hang them so they clear the sill and open them fully each morning — trapped moist air behind a closed curtain is the one way this fix backfires.
Pros
- Raises the glass-side air temperature at night
- Also cuts heat loss and street light
- No installation beyond hanging them
- Works on single and double glazing
Cons
- Must be opened each morning or moisture gets trapped behind them
- Needs correct sizing for the window
Who it's for: Bedrooms where windows stream every winter morning
Check Price on Amazon UK →BKSAI Window Insulation Film
The cheapest way to mimic double glazing. The trapped still air layer keeps the inside surface several degrees warmer, which is often enough to stop condensation forming on that window entirely for the whole winter.
Pros
- Creates a secondary glazing air gap for under £25
- Big jump in inner surface temperature
- Renter-friendly — removes cleanly in spring
Cons
- Fiddly to fit neatly
- Window can't be opened while fitted
Who it's for: Single-glazed or old timber windows in rented flats
Check Price on Amazon UK →FuKuEn Window Condensation Absorber Strip
Stick it along the base of the pane and it soaks the water up before it reaches the frame. It will not lower humidity, but it buys your sills years while you fix the underlying cause.
Pros
- Cheapest product here
- Stops run-off pooling on timber
- Trim to any width
Cons
- Manages the symptom only
- Needs wringing out in peak winter
Who it's for: Wooden sills already showing water staining or peeling paint
Check Price on Amazon UK →Devola 12L Dehumidifier
The only product on this list that removes the cause. Set it to 50% RH in the room with the worst windows, run it overnight, and by morning the glass is dry. Running costs are a few pounds a month — far less than the damage persistent damp causes.
Pros
- Humidistat holds the whole room at 50% RH
- 12 litres a day capacity
- Stops condensation forming rather than mopping it up
- Dries laundry indoors without steaming the windows
Cons
- Highest upfront cost
- Uses roughly 5-8p an hour to run
Who it's for: Homes with daily winter condensation and any sign of mould
Check Price on Amazon UK →ThermoPro Digital Hygrometer
Buy this first. Sub-55% RH overnight and your windows will stay dry. Above 65% RH and you need the dehumidifier. It turns guesswork into a number you can act on.
Pros
- Tells you if a fix is working
- Tracks daily min and max
- Cheap and accurate
Cons
- Removes no moisture itself
Who it's for: Anyone trying more than one fix and wanting to know which worked
Check Price on Amazon UK →Thermal curtains — the winter-specific solution
Most condensation advice is about lowering humidity. Thermal curtains attack the other half of the equation: they change how cold the surfaces near the glass get. A thermal lining slows the convection loop that drags warm, moist room air down the cold pane, so far less moisture ever reaches the dew point.
They also stop the room losing heat through the glass, which keeps the whole room warmer for the same heating spend — so the fix pays for itself over a UK winter.
The one rule: open them fully every morning. A closed curtain over a wet window traps damp air against the glass all day, and that is how mould appears on the frame and the curtain hem. Open curtains, wipe the glass, then let the room air.
Dehumidifier vs ventilation in winter
Ventilation is free but costs heat
Opening windows works: cold outdoor air is very dry, so exchanging it for warm damp indoor air lowers your humidity fast. The cost is heat. Ten minutes of purge ventilation each morning is a sensible trade. Leaving a window on the latch all winter is not.
A dehumidifier does the same job without losing heat — in fact it adds a little warmth, because the compressor's waste heat goes into the room. At roughly 5-8p per hour it is cheaper than heating air you have just thrown out of the window.
We recommend
The winning winter combination
Ten minutes of morning purge ventilation, thermal curtains on the worst windows, and a dehumidifier set to 50% RH overnight. That combination eliminates winter condensation in almost every UK home without leaving you cold.
Room-by-room winter condensation guide
Bedroom. The worst room in most homes. Two sleeping adults release around a litre of moisture a night into a closed, unheated room. Thermal curtains plus a dehumidifier, and leave the bedroom door open where you can.
Bathroom. Run the extractor for 15 minutes after every shower, keep the door closed while it runs, and squeegee the screen. Steam that escapes here ends up condensing on bedroom windows.
Kitchen. Lids on pans, extractor on while cooking, and never dry laundry over a radiator here. Boiling a pan uncovered puts a litre of water into the air in twenty minutes.
Living room. Usually the warmest room, so it condenses least — but it is where most indoor laundry gets dried. Move drying to a heated airer under a cover with a dehumidifier running.
Spare rooms and box rooms. Unheated rooms with the door shut are mould traps. Keep the door ajar so warm air circulates, and check the corners of external walls monthly.