Why Is Condensation on Windows Such a Problem?

Condensation on windows is more than just an annoyance — it spoils your view, leaves water on window boards, dampens curtains, and in the worst cases, causes mould on the plaster.

So, what can we do about it? How do we fix and prevent condensation from forming in our homes? Let’s break it down.

What Is Condensation?

Condensation occurs when moisture in the air hits a cold surface and turns from vapour back into liquid. This is a natural process but points to humidity problems and poor ventilation in the home — both of which can lead to long-term property damage and mould.

Why Does Condensation Form on Windows (Especially New Ones)?

Interestingly, condensation is more noticeable on modern, energy-efficient windows — and that’s because they’re working!
Older windows allow moisture to escape through small gaps and leaks. But newer windows are airtight, trapping that moisture inside. When warm, humid air hits the cold glass (often the coldest surface in the room), condensation forms.

Condensation can also form due to high humidity indoors, caused by activities like:

• Taking hot showers
• Boiling kettles
• Cooking meals

In short: warm, humid air + cold surface = condensation.

How to Reduce Condensation in Your Home

1. Showering or Bathing

• Take shorter, cooler showers to release less steam
• Always open a window before or after your shower for 10–15 minutes
• Use your bathroom extractor fan during and 15–20 minutes after showering
• Use a bathmat to prevent excess floor moisture, and dry it regularly

2. Cooking or Boiling Water

• Use pan lids when boiling food
• Always switch on the cooker hood/extractor fan and leave it running afterward
• Avoid letting steam build up in the kitchen

3. Close Kitchen & Bathroom Doors

Keep moisture contained. When cooking or bathing, close the doors to stop humid air from escaping into colder rooms where it will condense.

4. Laundry Drying

• Avoid drying clothes indoors on radiators or airers
• If drying inside is necessary, use a vented tumble dryer or condensing dryer
• Outdoor drying is best when weather allows

5. Using Gas Appliances

Gas ovens and hobs release water vapour, CO₂, and possibly CO.
Ensure your kitchen is ventilated to allow these byproducts to escape.

6. Home Renovations

Painting or plastering? These wet materials release moisture as they dry.
Keep windows open and rooms ventilated while decorating.

In Summary

Condensation is a clear sign of high humidity and poor airflow in your home. Luckily, small changes — like using extractor fans, closing doors, ventilating properly, and managing moisture-producing activities — can make a huge difference.

If you’re dealing with persistent condensation, it might also be worth considering a dehumidifier or a home ventilation system.