Window Condensation: Easy Solutions

Written by Daniel Woodley. Fact checked by Paul Farley.  Published to Blog on the 23rd of January 2022.

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In the winter, most of us keep our windows closed, turn on the heating and do our best to keep our homes warm and comfortable.

It’s also a time of year when many of us see a build-up of condensation on our windows, the frames, or even on our plaster walls near the windows.

Keep reading to see how to get rid of window condensation quickly and easily.

But First… If The Window Unit Has Failed:

If you have Upvc triple or double-glazing windows and you can see condensation between the panes of glass, this means the sealed unit has failed.

The “unit” is made from two or three panes of glass, sealed at the edges. and the space inside filled with gas.

The good news is that the glass unit can be removed and replaced with a new one, and from my experience, I know it only takes about 10 minutes to remove the window unit and replace it. You don’t need to replace the entire window, just the glass unit.

In 2023, I found this website that can provide you with a price based on the size and thickness of the window glass.

In January 2023, a 1000mm x 900mm double-glazed unit from them cost £135 inc VAT.

A professional window fitter can replace the unit for you, but competent DIYers should also be able to do this – I’m not a window fitter but I found it very easy to replace the unit in one of my windows. Here’s a YouTube video showing how easy it is to replace a window glass unit:

5 Ways to Reduce Condensation on Windows, Walls and Ceilings

Condensation is caused by the lifestyle of the occupants.

They produce moisture in the home by:

  • Breathing.
  • Sweating.
  • Cooking.
  • Drying clothes on radiators.
  • Showering bathing.

Here’s how to stop condensation forming on windows:

1) Improve Ventilation

I’ve found that some properties are so well sealed that the moisture created by the occupants can’t escape.

It builds up in the air until it comes into contact with a cold surface, such as a cold wall or window, where condensation then forms.

My first recommendation is to install window trickle vents if you haven’t done so already. I’ve seen first-hand how these vents can drastically reduce condensation as I’ve fitted dozens of them in the past.

In July 2022, the UK’s Building Regulations were updated. Now, all new Upvc windows must have trickle vents installed.

This isn’t optional; it’s part of the official Building Regulations. and the rules apply to both newly built homes and retrofit projects.

Competent DIYers and professional window fitters can install these vents, and I know from experience that they work very well:

Window trickle vents

Window trickle vents are sold on Amazon

There are other ways to improve ventilation:

  • Install or upgrade bathroom extractor fans.
  • Install or upgrade kitchen hood extractor fans.
  • Install loft vents (gets rid of loft condensation).

2) Reduce How Much Moisture is Created in the Home

In addition to improving the ventilation, the occupants of the home can reduce the amount of moisture they create by:

Not drying clothes on radiators – use a tumble dryer or, at least, open a window to vent the moisture created by the radiator.

Opening a window after showering or bathing.

Using extractor fans in the kitchen when cooking.

Opening windows slightly in the bedrooms in the morning.

3) Upgrade The Windows

Old windows are often much colder than their modern equivalents.

Windows with single panes of glass are notorious for condensation, as are failed older windows.

If your windows are really old, consider upgrading them to warmer, modern ones, as less condensation will form on the warmer glass and plastic frame.

4) Check Insulation

Condensation will only form on cold surfaces, so if you’re seeing damp, black spots or condensation in one specific area, it could be due to missing or faulty insulation.

Examples of this I’ve personally seen are:

1) Gaps in cavity wall insulation where a certain area is very cold and condensation forms.

2) Missing loft insulation which leads to cold spots on the ceiling where condensation forms.

Warming these cold spots by filling in any gaps in the insulation is good practice, but improving the insulation won’t entirely cure a severe condensation problem.

5) Dehumidifiers

Dehumidifiers pull moisture out of the air and deposit it into a tray or bottle, the user can then dispose of it.

The best dehumidifiers are electric, but they can be bulky, noisy and consume lots of power.

For small areas such as wardrobes, food cupboards and even bathrooms, consider chemical dehumidifiers.

These containers contain small round balls that attract moisture which is then trapped in the tub.

Dehumidifiers should be seen as a short-term solution rather than a permanent cure.

Chemical dehumidifiers

Perfect for small areas – sold on Amazon

This is What Happens If You Don’t Cure Condensation

Mild condensation during particularly cold weather is perfectly normal, I even get this sometimes in my home.

Many of us see it in our bathrooms after showering or on the bedroom window in the morning.

What isn’t normal is large puddles on windowsills or water pouring down the window panes.

When severe condensation is left unchecked, it can lead to mould, black spots, damp, damaged plaster and rotten wood.

In extreme cases, it can lead to breathing difficulties and health problems.

Condensation on Windows: A Recap

Moisture is formed by the occupants in the home and in the winter when the doors and windows are closed, it can build up in the home.

High levels of humidity (that’s the amount of moisture in the air) can lead to damp, black spots, mould and health problems.

The best way to get rid of condensation on windows, walls and ceilings is to:

  • Reduce the amount of moisture being created in the home, especially in winter.
  • Improve ventilation.
  • Replace cold windows with newer, warmer, modern versions.
  • Improve insulation so there are fewer cold surfaces.

Dehumidifiers do work but should only be used as a temporary solution while the main condensation issue is being rectified or investigated further.

The only way to tell if you have high humidity in your home is to check the air with a humidity tester.

I have one in my front room and I purchased it from Amazon back in 2021:

Humidity tester

As you can see, in my front room, the humidity level is 41% which is in the normal range.

When I dry clothes on my radiator, it peaks at 65% for an hour or so and a little condensation forms on the windows for a short while.

What are the readings in your home?

Are they too high for too long?

Find out by taking humidity readings with this cheap device.

Examples of Normal Condensation

It’s normal to see some condensation on windows and other cold surfaces.

Here are some scenarios:

Condensation on bathroom mirrors or windows during a bath or shower.

Kitchen windows misting during cooking, boiling water etc.

Condensation when drying clothes on radiators.

In a properly ventilated home, the moisture and condensation should clear after a short amount of time (hours).

In a home with inadequate ventilation, the moisture may persist for days, resulting in mould, black spots and damp forming on walls, around window frames, and on ceilings.

The moisture may also make its way into the loft and condensate there as well.

Author: Daniel Woodley

Daniel has over 18 years of experience in the construction, home improvement, and landscape garden industries.

He previously worked as a project manager and has experience in managing teams of tradespeople and landscape gardeners on both small and medium sized projects.

Daniel is also a keen gardener and enjoys growing unusual plants and tending to his lawn.

More About Daniel Woodley.

Daniel Woodley

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Daniel Woodley has experienced issues with condensation in his home and in the loft, and this guide is based on that experience.

As accuracy is important, we asked Paul Farley to review and fact-check this guide.

Explore: Paul Farley’s profile and qualifications.

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