You wake up, the bedroom windows are streaming, and there’s a little puddle forming on the sill. When people ask what should I do about condensation on my windows, they’re usually worried about two things: the mould that follows, and whether it means their windows are failing. The reassuring news: condensation is almost always a ventilation and lifestyle issue, not a window defect.
I’ve lived with chronic window condensation in two houses — one with ancient single glazing, one with brand-new double glazing, which tells you everything about the real cause. Here’s why it happens, the daily habits that fix most of it, and the upgrades for stubborn cases.
What should I do about condensation on my windows? Understand the cause
Condensation forms when warm, moist indoor air hits a cold surface — your windows are simply the coldest surface in the room, so they show it first. A family of four produces 10–15 litres of moisture a day through breathing, cooking, showering and drying clothes. Modern homes, sealed up with double glazing and draught-proofing, trap that moisture inside; ironically, the better sealed your house, the worse the condensation can be. New double glazing often ‘causes’ condensation complaints for exactly this reason — the old draughty windows were ventilating the house.
The pattern tells you the source. Condensation on bedroom windows in the morning is breathing moisture overnight — normal, and fixed with ventilation. Streaming kitchen windows after cooking means the extractor isn’t coping. Condensation between the panes of double glazing (that you can’t wipe off) is a failed sealed unit — that’s a window problem, and the unit needs replacing. And condensation on walls rather than windows suggests cold spots or insulation gaps worth investigating.
- Morning bedroom windows: breathing moisture — ventilate
- Kitchen/bathroom: cooking/showering steam — extract it
- Between the panes: failed sealed unit — replace the glass
- On walls: possible insulation or cold-bridge issue
The daily habits that fix most condensation
Before spending anything, change the routine — this resolves most cases. Open bedroom windows for 10–15 minutes each morning, even in winter; the blast of cold air carries the night’s moisture out and costs almost nothing in heating. Always use extractor fans when cooking and showering, and leave them running 20 minutes after. Put lids on pans, don’t dry clothes on radiators (a heated airer in a ventilated room, or better, a dehumidifier nearby), and keep the heating on low and steady rather than blasting it morning and night — warm air holds moisture, cold surfaces condense it.
Wipe down windows each morning with a microfibre cloth or a window vacuum — a Karcher-style window vac (£35–£55) turns a grim chore into a two-minute job and stops water pooling on sills and feeding mould. Keep furniture slightly away from external walls so air circulates, and don’t block trickle vents on windows — they’re there for exactly this. These habits sound mundane, but I eliminated 80% of my condensation with just the morning airing and the window vac.
Upgrades for stubborn cases
If habits aren’t enough, upgrade the ventilation properly. Trickle vents in window frames provide background airflow for about £15–£25 per window fitted — cheap and effective. For bathrooms and kitchens, a humidistat extractor fan that runs automatically when moisture rises (£80–£150) removes the human-forgetfulness factor entirely. In houses with persistent whole-house condensation, a single-room heat-recovery ventilator (£300–£500 fitted) extracts stale moist air while recovering most of the heat — the grown-up solution that actually works.
A dehumidifier is the brute-force option: a decent 10–12 litre unit costs £130–£200 and will pull litres of water from the air daily, making a dramatic difference in damp houses. Run it in the worst room with doors closed, and empty it (or plumb it to a drain). The running cost is roughly 20–30p an hour — not nothing, but cheaper than redecorating mouldy walls. What I’d skip: anti-condensation paint (marginal benefit), and those little disposable moisture traps (fine for a wardrobe, useless for a house).
New builds, rentals and special cases
New-build homes are condensation factories for the first year: the construction materials (concrete, plaster, timber) hold enormous moisture that dries out over 6–12 months, a process called ‘drying out’. If your new build streams with condensation, it’s usually normal — ventilate aggressively (the trickle vents and extractor fans are there for exactly this), heat consistently rather than in blasts, and don’t dry clothes on radiators. It improves markedly by the second winter. If it doesn’t, the ventilation system (many new builds have MVHR — mechanical ventilation with heat recovery) may need checking or filter changes.
Renters: you can’t install fans or vents, but you can do everything in the habits section — and you should report persistent condensation in writing, because chronic condensation causing mould is a disrepair issue. Landlords must provide adequate ventilation and heating; a bathroom with no working extractor fan is the landlord’s problem to fix. Document with photos and humidity readings. And one special case: condensation in only one room, on one wall, that never improves — get it checked for a hidden leak or cold bridge rather than assuming it’s lifestyle. Patterns that don’t respond to ventilation aren’t ventilation problems.
- New builds: drying-out condensation is normal for 6–12 months
- Renters: habits are yours, fans and vents are the landlord’s
- Report persistent condensation + mould in writing with photos
- MVHR filters in new builds need regular changing
- Condensation that ignores ventilation = investigate, don’t ventilate harder
Winning the condensation battle
Ventilate daily, extract moisture at source, wipe windows each morning, and upgrade fans and vents if habits aren’t enough. Condensation is your house telling you the moisture balance is off — listen to it before it becomes a mould problem.
For the mould that follows condensation, remove mould from bathroom walls permanently is the permanent fix, and double glazing cost for a 3 bed house in the uk covers when new glazing is genuinely the answer. For ventilation advice, the Energy Saving Trust’s advice is excellent and the UK government’s energy efficiency guidance covers the official guidance.
The condensation mindset: it’s data, not disaster. Where it forms, when it forms, and how it responds to ventilation tells you exactly what’s wrong — and most of the time, what’s wrong is fixable with habits, not hardware. Read the patterns, act on them, and the windows stay clear.
