Condensation on new windows is one of the most common concerns we hear from Leicester homeowners.
You finally get new double glazed units fitted, and within weeks, water droplets are forming on the inside. Is this normal? An installation fault? Or something else entirely?
In this guide, we break down why new windows get condensation inside, when it’s harmless (and when it’s not), and practical steps to stop it ruining your home – from simple ventilation fixes to when it’s time for a professional check.
Let’s jump in.
What is Condensation on Windows?
Condensation happens when warm, moist air hits a cold surface.
Your home produces moisture every day: cooking, showers, drying clothes, and even breathing. When that humid air meets glass cooled by the outdoors, water droplets form.
Three types of window condensation:
- Inside the room – Normal on cold nights, especially with new, efficient windows.
- Outside the glass – A good sign! Shows your double glazing is trapping heat effectively.
- Between the panes – Trouble. This means a failed seal (misted windows) and needs fixing.
New windows often show more inside condensation because they’re so airtight – less heat escapes, keeping the glass colder relative to your room air.
Should New Windows Have Condensation Inside?
Yes, it is normal for new windows to have condensation on the inside surface, especially during the colder months of the year and the first few months after installation.
Here’s why:
- Modern A+ rated double glazing with warm-edge spacers and argon gas is brilliant at insulation. The inner pane stays colder than older single glazing, so dew forms more easily.
- Your home’s humidity takes time to stabilise post-install. Cooking steam, bathroom moisture and winter drying all contribute.
When to worry:
- Heavy puddles pooling daily, especially in bedrooms or mornings.
- Black mould forming on sills or frames.
- Water trickling down walls or damaging plaster.
- Condensation between panes – definite seal failure.
If you’re seeing the last one, don’t panic – a misted window repair service can often fix it without full replacement.
Why Do My New Windows Have Condensation Inside?
Leicester’s damp climate doesn’t help, but here are the usual suspects:
- High indoor humidity – Kettles boiling, tumble dryers venting indoors, no extractor fans.
- Poor ventilation – Rooms closed up, no trickle vents, blocked air bricks.
- Cold spots – Rooms not heated evenly, curtains trapping moist air against glass.
- Lifestyle – Wet boots in halls, unvented drying racks (classic in Victorian terraces).
New windows make it more noticeable because old leaky ones let moist air escape unnoticed.
7 Proven Ways to Stop Condensation on New Windows
Here are some tips to stop condensation from forming on new windows:
- Wipe it away daily – Use a microfibre cloth morning and evening. Stops water pooling and mould starting.
- Ventilate properly – Open windows 10 mins daily (even in winter). Use extractor fans when cooking/showering.
- Add trickle vents – If absent, these let air circulate without compromising security.
- Dehumidifier magic – £100-200 units pull 10-20L moisture daily from the air. Place near worst windows.
- Heat smarter – Keep rooms 18-20°C, avoid cold spots. Radiators under windows help warm the glass.
- Avoid moisture traps – Dry clothes outside or vent tumble dryers. Keep lids on saucepans.
- Upgrade glass – Low-E or triple glazing reduces cold surface temps. Ask about retrofits.
Do Windows with Inside Condensation Need Replacing?
Not usually. Surface condensation is environmental, not a window fault. But if you have:
| Condensation Type | Action Needed |
|---|---|
| Inside surface | Ventilation tweaks (above) |
| Between panes | Misted repair |
| Mould damage | Clean + ventilation upgrade |
| Walls wet | Professional survey ASAP |
20+ year old windows? Upgrading to Phair Windows A++ units often solves it permanently while slashing bills.
Window Repairs and Replacement From Phair Windows
If you’re based in Leicestershire and looking for misted window repairs or to upgrade to the most energy-efficient A+ rated windows and doors on the market, get in touch with our expert team for a free quote.
Frequently Asked Questions
High indoor humidity plus cold glass. Ventilate more, use a dehumidifier, and keep rooms warmed evenly. Outside misting? Your windows are doing their job brilliantly.
Not if it’s just on the inside surface – normal in winter. Worry if it’s between panes (seal failure) or causing mould/water damage. Check frames and sills for gaps too.
No – that’s a fault. The argon gas or seal has gone, letting moisture in. Contact your window installer ASAP.
They help a lot by letting controlled airflow through without opening windows. Great for security-conscious homes.
