Window Condensation FAQs

Condensation isn’t limited to windows and can form throughout your property. 

Condensation is most commonly associated with windows, where moisture builds up on the glazing and pools of water form around the corners of the frame. 

However, your walls and ceilings can also experience condensation in areas of the property with excess moisture.

Window condensation is caused by excess moisture hitting a cold surface – in this case, your glazing. Crucially, that excess moisture will be warmer than the surface it is hitting, causing condensation. 

The difference in temperature means it is cold enough for molecules to combine to form the visible liquid that sits on the surface of your glass

There are three different types of window condensation to be aware of: condensation on the inside of your windows, on the outside of your windows and lastly, within the cavity of your window. 

It is important to recognise how they differ and the solutions involved in resolving the different styles of window condensation. 

Condensation on the inside of your window means the temperature of the glass is too low, relative to the water vapour contents of the room’s atmosphere.

This should be removed safely as quickly as possible to prevent water build-up and mould growth. If left untreated, it could cause damage to your window’s structural integrity in the long run. 

Condensation on the outside of your window is a positive sign that your glazing is working as intended by preventing internal heat loss.

Having double or triple-glazed glass means that your outer pane of glass is not heated by any lost heat escaping from your home.

It is most common during the earlier hours of the spring and autumn mornings. It doesn’t require clearing and will evaporate naturally as temperatures rise throughout the door.

Finally, condensation can occur within the cavity of a window if damp air has penetrated a gap in the seal.

A double-glazed window is a sealed unit and is designed to not let in any air – so if you do experience this, your seal has failed and the unit will need to be replaced as soon as possible.

A regular ventilation routine is crucial to preventing condensation as it allows air to circulate throughout your home. 

Ensure all rooms are well-ventilated each day, all year round. 

Further preventative measures include: 

• Upgrade your glazing: Older single-glazed windows will not be able to offer the same level of thermal performance as a double or triple-glazed unit.
• Draught-proofing: Close off rooms to avoid moisture travelling through your home. Trapping moisture in one room will make it easier to manage.
• Install extractor fans: Extractor fans allow another form of escape from moisture when using your kitchen or bathroom.
• Dry clothes outside: Avoid leaving damp clothes to dry inside. Where the weather allows you to, always try to have clothes drying outside. 
• Use a dehumidifier: They can be a helpful tool when you need to dry laundry inside, or just remove excess moisture from an area of your home.
• Add house plants to high-moisture areas: Peace Lily or Aloe Vera plants are smart choices if you’d like to add a house plant to an area of high moisture. When tactically positioned in your home, they can help absorb excess moisture. 

Consider opening a window, or if you are sleeping in a room with a skylight, opening the ventilation flap, or if your windows have trickle vents, leaving these open. 

New build properties can be prone to condensation due to the moisture build-up during the build phase.

This is not a fault of the building or a reflection of the quality of the build process. However, the sheer volume of materials used during the build , from plaster, cement, paint and more, means there is excess moisture trapped inside the property from the start.

New build homes are now so well insulated in comparison to older buildings, it takes time for this moisture to escape.

This is known as the ‘drying out phase’ and can take between six and 12 months following the completion of the build. 

Regular ventilation over the first 12 months of residency will aid your drying-out process. 

Ensure windows are open for between five and 20 minutes each day, even in winter.

If you experience consistent condensation beyond 12 months, contact the NHBC (or equivalent) for more information and support.

Double glazing can prevent window condensation by providing an insulation barrier to the external side of your glass.

Double glazing reduces thermal transmittances and retains heat in your property.

Keeping the internal side of the glass warmer prevents moisture build-up.

It is recommended that you open the windows in your home for at least five minutes each day, but if you can extend this to 15-20 minutes that would be advantageous.

It is important to have a regular source of ventilation in your home to allow for circulation around the property. It is also an opportunity for built-up warm moisture to escape.

Philips recommend that your home should sit between 30% and 60% in all rooms of your house for optimal performance.

You can monitor this by investing in a small tool called a hygrometer. This will read the humidity levels in a room. It looks like a standard thermostat and is a valuable, inexpensive tool you can add to your property. Usually available for under £10, they can be purchased online or in your nearest DIY retail store.

House plants can be a good source of preventing condensation in your home, especially when they are positioned strategically. 

Plants like Peace Lily or Aloe Vera are smart choices to absorb excess moisture. However, you should be cautious about how many houseplants you have inside. Add too many to your property and you risk adding more moisture to the building.

To safely remove condensation, use a clean, dry cloth to wipe the surface clear. Use a second dry cloth to ensure the now-clear surface is dry.

Ensure that all excess moisture is removed from the surface to prevent mould growth. 

Yes, you should wipe away any condensation that has built up the internal side of your glazing as soon as you can.

Leaving excess moisture to form for any longer than it needs to will encourage mould growth in this area.

Condensation that has formed on the outside of a double-glazed window does not need to be removed. This will evaporate throughout the day as the surface warms up.

Low-e glass can still experience internal and external condensation. Internal condensation is less likely when compared to alternative glass types because low-e glass is a reflective surface. 

Interior heat bounces off the glass and remains inside your home. This ensures the outside of the surface is cool.