Top tips on reducing condensation room by room

What is condensation?

Condensation forms when warm wet air meets a cold surface, water droplets will then form on the cold surface. Most home owners will see this as droplets on the inside of their windows.

Condensation happens one of two ways: Either the moisture laden air is cooled to its dew point or it becomes so saturated with water vapor that it cannot hold any more water. The dew point is the temperature at which the air condensates and releases the water. It can be a different temperature depending on how much water is present in the air.

If your home is suffering from condensation you can reduce condensation build up by removing excess moisture through ventilation. This can be done without making draughts or causing rooms to become cold. Moisure laden air takes more energy to heat than dry air.

Is your home a moisture trap?

Modern buildings are designed to eliminate draughts and do not have the natural ventilation that some older houses have with their chimneys and ill-fitting windows and doors.

As a result, houses that have been completely sealed by the installation of cavity wall insulation, loft insulation, double or triple glazing, and draught proofing can often become moisture traps.

In such cases, condensation can generally be seen as a ventilation problem. Provided the rooms are heated adequately, a solution will probably be found in the provision of effective ventilation.

By opening windows or ventilating your home it may appear that you are losing some heat. What you are actually doing is allowing warm moisture-laden air to escape and permitting cool dry air to enter your home. Dry cool air is cheaper to heat than warm moist air.

How to reduce and prevent condensation

Bathrooms, How to prevent condensation and mould in your bathroom

• Stop water vapour, steam and condensation from finding its way into the rest of the house, particularly during and after baths and showers.
• After a bath or shower, close the bathroom door and open the bathroom window for a few minutes to let the damp air out.
• Position the radiator, or heated towel rail, under the window.
• If you don’t have a window consider installing a bathroom extractor fan to help pump the condensation steam from the bathroom.

Bedrooms. How to prevent condensation forming on windows overnight

• Humans release a lot of moisture as they sleep both from the skin and also as they breathe.
• As this warm wet air meets the cold glass of the window condensation will start to form as droplets of water on the window.
• Ensure bedroom curtains are at least 15cm to 20cm away from window glass to allow free movement of warm air. This will reduce mildew forming on the fabric of the curtain as it rubs against the condensation on the glass
• Open the trickle vents on your double glazed windows, to allow the dry outside air into the bedroom.
• Bedroom windows or trickle vents should be opened during the day to allow at least one complete air change.
• If possible extend the central heating programme to compensate for the night-time drop in external temperature, and the increase in water vapour caused by the occupants’ breathing during sleep.
• Where open fires are not provided, or existing flues are blocked off, see that wall vents are fitted and kept clear.

Kitchens and laundries contribute to condensation

• Steam from cooking a meal contributes to the moisture and condensation in your home.
• Your tumble dryer will also release moisture from the washing into the air of your house, unless the machine is vented to outside air.
• Hanging wet clothes on radiators will also release moisture into the air, increasing the chance that condensation will form on walls at night. So consider opening windows or trickle vents to ensure this wet air leaves your home.
• Close the internal kitchen door when cooking and keep a window open. Alternatively, install kitchen extractor fan or cooker hoods that ventilate damp condensation to the outside air.

Living rooms. Preventing winter condensation problems

• As we spend more time indoors during the winter, watching tv or playing games, moist air from our breath contributes to condensation problems especially when it meets cold winter windows and walls.
• Allow the room’s warmth to reach the windows. Position heaters under the windows and place curtains at least 15cm to 20cm away from the glass to allow free movement of warm air.
• Moist air takes more energy to heat than dry air, so opening a window to let out damp wet air will help a room feel warm and dry faster.
• Open windows for a few minutes each day to permit air changes. Or leave your trickle vents open if you are concerned about security. They are designed to allow a steady flow of air in and out of a room when a window is closed helping reduce condensation.
• Where open fires are not provided, or existing flues are blocked off, see that wall vents are fitted and kept clear. When a gas fire has been installed in an old fireplace, the back plate should have vent holes below the fire, unless provided for in the design.
• Where possible, avoid glazed or non-absorbent wall coating, as this can promote condensation on walls.

Conservatories

• Conservatories can go through some extreme temperature changes over a day and a night. These changes mean that any moisture in the air can change to condensation as it hits cold glass.
• Keep furnture and plants 15 cms from the walls or glass so air can move freely. This will reduce mildew forming in condensation hot spots.
• If you have trickle vents, these should be open during daylight hours and closed at dusk when damp air, dew forms outside.
• Consider crossflow ventilation with the use of vents in walls and roofs especially if the conservatory is south facing.

• Trickle ventilation in the wall, eaves and ridge zone can also help.

For more advice and information about reducing condensation in your home, get in touch with a local GGF Member company.

Related topics

– What is condensation and why does it occur on windows?
– Window condensation – where the water vapour comes from
– How double or triple glazing helps reduce window condensation
– Where condensation can form on a window and how to reduce it
– A guide to home ventilation