Condensation on windows

This is a problemfor many of us have encountered at some point. Its a common problem which can cause many issues. So why do windows condensate?

If you have ever opened the curtains to find the windows dripping with water inside, or found pools of water on the windowsills then you will be all too aware of the other issues this causes. Black mould can start to appear around the window reveals which is a sure sign of dampness getting into the walls. Sound familiar?

You probably wondered where the water is coming from, and how to stop the build-up of water inside of your windows. During this guide, we will discuss the causes of condensation on windows, and how to solve the problem.

Preventing condensation on windows is actually a lot easier than you probably think. Once you understand what actually causes condensation on windows you will be better prepared for stopping it from happening.

Window condensation is quite a common problem. There are numerous reasons why we get condensation on the inside of our windows. In order to find out how and why it happens, we need to determine the cause.

Window condensation Causes

What causes condensation on windows?

Condensation occurs either when warm air meets a cold surface, or because of excess humidity in the home. When the warm air packed with moisture meets a cool surface, the air cools quickly releasing the water, which appears as small droplets on the cold surface.

Moisture is created in our homes from performing our daily routine activities such as cooking, showering, washing and drying clothes. The moisture gets trapped inside of our homes due to the thermal efficiency of modern housing and double glazed windows. 

There are measures homeowners can take to prevent the build-up of humidity in the air, leaving windows on weather lock, opening trickle vents, running a dehumidifier all help to reduce humidity and in turn prevent condensation.

Window condensation is more prevalent in colder months due to the warm air in your home holding more moisture than cold air would do. When it’s colder outside, the window frames are obviously much colder. When the warm, moisture-filled air in your home collides with the colder surface of the window frames the air deposits tiny water droplets causing condensation.

How to stop condensation on windows

There are several things you can do to stop the build-up of condensation on windows, some are simple measures that can be done right away, others would require some installation.

Simple changes to prevent condensation:

Installations to prevent condensation on windows:

How to stop condensation on bedroom windows

Bedroom windows can be particularly problematic, you most likely notice condensation on your bedroom windows in the mornings, this is caused because we tend to keep our bedroom warmer than other rooms, we then create additional moisture in the air whilst we sleep which is caused by us breathing. 

Apart from keeping a window open or opening a trickle vent if they are installed, what else can we do?

Install Ventilation Systems

The best way to prevent condensation on windows permanently is by installing a ventilation system in the home, these systems work better than trickle vents or opening a window. Let’s take a look at the different ventilation systems available:

Passive ventillation unit

A Passive ventilation unit is a cost-effective way of purging the air, best suited to bathrooms or kitchens, these units are low tech with zero moving or mechanical parts. These units are simple to install and do not require wiring in, easily installed with basic D.I.Y skills and very low cost with an average price below £20 each.

condensation on windows

Heat recovery installation systems

A Heat Recovery ventilation system looks similar to a passive ventilation unit but it does have a major difference, it features an energy-efficient heat recovery unit that is designed to alleviate condensation. If you have rooms that suffer from major condensation or air quality issues then this unit will suit your needs better than a passive unit.
A heat recovery ventilation unit draws out the problematic moist air from within your home and replaces it with filtered, fresh air drawn in from outside.

A heat exchange unit uses the heat from the warm air in your home and uses it to warm up the incoming fresh air, this function makes the unit energy efficient.

heat recovery room ventilator

Positive Input Ventilation Systems (PIV)

Positive Input Ventilation (PIV) is an energy-efficient method of purge ventilating your home by replacing moisture loaded stale air with fresh air by constantly flooding your home with clean filtered air and optimising the circulation of fresh air around the whole house improving the air quality within the house.

Condensation on windows and how to stop it

All of these units are fantastic ways of preventing condensation in the home, which one you choose would depend on the amount of condensation on the windows. Remember that condensation isn’t usually an issue during the summer months, the amount of humidity inside of our homes peaks during the winter months. Because condensation is a seasonal issue most of these filtration units won’t need to be on all year round.

If you think a little bit of water is harmless enough, think again, if condensation isn’t dealt with black mould twill begin to appear on ceilings, walls and all around the affected windows in the room. Black mould is not only unattractive, it can also cause some serious health issues including rashes, and even bronchitis.


How do I deal with condensation in my home?

As we have discussed throughout this article, the first thing you should do to tackle condensation in your home is to clean up the affected areas. Gather some tools such as a squeegee, sponge, and some lint-free cloths. clean and dry the double glazed windows and surround areas thoroughly, open windows and doors and allow the air to flow through the home.

Now that home is dry and moulds free, steps should be taken to prevent the condensation issues from happening again. The simplest solution is to set up a dehumidifier to reduce the humidity in the home.

Making changes when performing activities at homes such as cooking and cleaning can also make a huge difference. When cooking, for instance, prevent steam from pouring into the air by keeping lids on your saucepans use an extractor fan if one is fitted, if not then consider getting one installed. Take shorter showers, or shower with a window opened or on a weather lock. Do not dry clothes indoors especially on a radiator as this will cause unwanted humidity.

What causes condensation on windows?

Condensation is caused by humidity in warm air, when it meets cold surfaces the air cools and leaves the humidity as little droplets of water on the surface. It is a common misconception that new windows won’t or can’t get condensation on them, this is not true, windows or doors of any age can get condensation with the right amount of humidity in the air.

How do I stop condensation forming on my windows?

Regulate the temperature in every room of the house, keeping a constant temperature is important. Keep the door closed in any room in the house that you don’t use often. Open the windows regularly in rooms of the home for at least a couple of hours every day to prevent condensation, mould and damp.

How can you stop condensation on windows overnight?

Open trickle vents in the windows put a window on weather lock, run a dehumidifier, allow air to circulate. Maintain a constant temperature in the house, keeping all rooms at the same temperature. Circulate the air in the house as much and as often as you can.