How to protect your home from condensation and mould

First Published: 19/02/2021

The air around us contains moisture and living in our home creates moisture. It’s a fact that four people living in a three-bedroom home can create 112 pints of moisture a week from just breathing, cooking, showering or bathing, and boiling the kettle.

Warmer air contains more moisture than cooler air. So when air is cooled rapidly the moisture it contains can turn into water droplets known as condensation. For example:

  • When you breathe out on a cold day, what you see is a cloud of tiny droplets as the warm air of your breath is cooled by the air around you.
  • When you breathe onto a mirror, what you see is tiny droplets forming on the surface as the warm air of your breath is cooled by the mirror.

In these examples, condensation is easy to see but you may not notice condensation on your walls, ceilings or window frames/reveals. If condensation is left on a surface for long enough black mould will begin to grow. This is one reason why it’s important to reduce and manage condensation properly.

Watch this video from EnviroVent for more information on condensation:


Ways to reduce condensation

  • Keep all vents and window vents open and clear.
  • Open windows when you can, (this brings in dry air from outside).  Try to do this for about 30 minutes each day.
  • Always ventilate your kitchen while you are cooking or washing up.
  • Keep your kitchen and bathroom doors closed to prevent moisture from escaping into your home.
  • Leave space between furniture and walls to allow air to circulate. Where possible do not place furniture against external walls.
  • It is better to heat your home gently throughout the day, than heat it for a brief period.
  • Because your daily life creates moisture in the air you can’t always prevent condensation, so you may need to manage it by wiping it down.


How can you reduce the condensation in your home?

Tip 1: Heating

Rather than having your heating on for an hour in the morning and evening, or for short periods when the room temperature feels cold, it is more cost-effective and better for the property to run the heating for longer periods at a lower setting. Keeping the heating on for longer periods of time, setting the room thermostat to between 18 and 21ºC and controlling the temperature within the individual rooms using the radiator controls (TRV’s) will keep both the property warm and reduce the risk of condensation.


Tip 2: Vent washers and driers

If you have a washing machine or tumble dryer in your home, ensure that it is vented correctly. From just one load of washing two litres of water is released into the air.


Tip 3: Drying clothes

Where possible, dry your clothes outdoors to prevent moisture from building up in your home. Otherwise, dry them in a bathroom or kitchen with the door closed and the fan on (or windows open) until the clothes are fully dry. Drying clothes on radiators releases a lot of moisture into the air quickly, creating a high risk of condensation.


Tip 4: Manage those steamy rooms

When cooking, showering or bathing:

  • Keep your kitchen or bathroom door shut to prevent moisture from escaping into other cooler rooms and forming condensation.
  • Keep the extractor fan on or the window open (not both – the air will just come in through the window and out through the fan instead of circulating through the room).
  • Keep the door shut and fan on for about 20 minutes after you have finished to properly ventilate the room.


Tip 5: Keep steam under control

When cooking, cover your pans with a lid to contain the moisture being created from water boiling.


Tip 6: Wipe moisture off your windows

Your windows are often the coolest part of your room so are prone to condensation. Keep curtains and blinds open during the day and wipe off excess condensation Open the windows slightly or use trickle vents if you have them. This will allow air to circulate which will reduce condensation and help moisture to evaporate.


Tip 7: Pets and plants

Many families have house pets and plants and these produce moisture too. Make sure you cover up your aquarium or fish tanks to prevent evaporation. If you start to notice mould or condensation near your house plants, think about moving them to a better-ventilated spot or outdoors.


Tip 8: Let the air get around your cupboards

Do not overfill your wardrobes or kitchen cupboards. Air moisture trapped in warm overfilled cupboards can lead to mould growth because the air can’t circulate freely inside. If you notice a musty smell or your clothes have a damp feeling to them, your cupboard or wardrobe may be overfilled.


Tip 9: Let the air get to your walls

Make sure that your furniture is at least 50mm away from the walls so that air can circulate behind. Internal walls are a bit warmer than external walls – try placing your furniture against internal walls to reduce the risk of condensation.


Tip 10: Manage your heating

Don’t let the walls and surfaces in your house get too cold: setting your heating to maintain a minimum temperature of 15°C will help to prevent condensation.


Tip 11: People breathe out moisture!

If you use a room regularly (such as a living room) and it’s not cold outside, open a window slightly to improve ventilation in the room. You and your family in a room together create moisture in the air just by breathing, so ventilate to help prevent condensation.


Tip 12: Use your extractor fans well

Make full use of your extractor fans and use them properly. Remember:

  • Some fans are designed to carry on running for a while after you switch them off – this is normal so you should leave them to run.
  • Some new fans have a ‘humidistat’ – this means they come on automatically when there is too much moisture in the air.
  • Don’t turn your fan off at the wall switch.