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Condensation/dampness

People often confuse condensation for dampness, when in fact they are quite different.

Condensation

Condensation is caused by the way we live – it’s the kind of thing you see when your bathroom mirror mists up. We can make simple changes at home to help protect it from damage caused by condensation.

This is an example of damage caused by condensation. Moist air has tried to escape, but can’t because the room is cold and not aired. Black mould spots have grown on cold outside walls and areas where air struggles to circulate.

Dampness

Dampness is caused by a structural problem where water is able to get in to your home from the outside, either by rising up from ground level (rising damp) or through a crack or gap in the wall or roof (penetrating damp).

This is an example of damage caused by dampness – water has got in to the house from outside. You can tell it is dampness because it forms a ‘tidal’ or circular pattern, and has white fluffy salt deposits as well as some mould spots.

You can help prevent damage being caused due to condensation. Warm moist air needs to escape, otherwise it settles on cold surfaces and can cause mould spots.

Although you can’t see it there is always some moisture in the air. Warm air holds much more moisture than cold air. As soon as warm air hits a cold surface it cools down and is forced to let go of some of the moisture carries, making the cold surface wet.

This “wetness” is condensation. The steam or mist that appears on your bedroom windows in the morning or in the bathroom mirror is condensation. The ‘breath’ that you can see when you go out on a cold day is condensation.

Condensation appears mainly in cold weather and is found on the coldest surfaces or in places where there is little or no movement of air. You will find it in the corners of rooms, or near windows or behind furniture.

It mostly appears on north facing walls which are colder because they don’t get the sun. The damp caused by condensation can cause mould to grow on walls, fabric and furniture—which eventually leads to rotting.

It can also cause paint to blister and wallpaper to peel off. Mould gives off tiny seeds called ‘spores’ - these spores float in the air (this is how it spreads) and can make conditions such as Asthma worse.

Modern improvements such as insulation to walls, draught proofing on doors and sealed window units have made it easier for you to keep your home warm by minimising draughts and stopping heat escaping from your home. But these improvements also stop moisture escaping, which is why people have much more of a problem with condensation these days.

There are a number of things you can do:

1. Make less moisture

  • Wipe the water from your windows and sills with a cloth, but make sure you wring your cloth out in the sink and don’t put the wet cloth on a heater to dry. Putting a wet cloth on a heater allows the water to evaporate back into the air which means it will re-appear as condensation when the temperature drops.
  • Don’t dry washing inside your home. All the water from your clothes will go straight into the air and as soon as the air cools you will get condensation on your windows and walls.
  • Put lids on you saucepans when you cook. This keeps steam in the pan and saves money on your fuel bill.
  • Don’t use paraffin or bottled gas heaters. They produce lots of moisture. Burning 1 gallon of paraffin puts about 1 gallon of water vapour into the air which re-appears as condensation on your windows or other cold surfaces.
  • Vent your tumble drier outside. If your dryer is not self condensing make sure you put the hose out of a window to ensure the hot, moisture filled air produced by the machine does not condense inside your home. Opening a window is not enough. You can get hose kits from most electrical & DIY stores.

2. Increase the ventilation 

  • Use the trickle ventilators in your windows. You need a good air flow to help get rid of moisture which is produced in your home all the time. Modern windows have pull down flaps to help ventilate your home. Keep these open as much as possible so damp air can escape. Open a window when cooking and after showering/bathing. Boiling pans, hot baths and showers produce lots of steam. Opening a window ensures this steam condenses outside rather than inside your home.
  • It also helps to keep your kitchen and bathroom doors shut when these rooms are in use for about 20 minutes after to stop moist air getting into other rooms. When your kitchen, bathroom or other rooms are not in use leave doors open so heat can spread evenly through your home.

3. Allow air to circulate

  • Don’t put furniture against the outside walls of your home. The inside walls (between rooms) are always warmer and are therefore less prone to condensation. Leave a gap between the wall and the furniture so air can circulate and ensure that wardrobes and cupboards are properly ventilated to prevent mould growing inside. 

4. Keep your home warm

  • When moisture condenses on your walls it makes them colder. This causes you to lose heat and increases the risk of mould growing. It then takes more energy to heat your home to a comfortable temperature which costs more. Heating your home efficiently helps reduce condensation and could save money on your heating bills. Try to keep your home above 18ºC (63°F) - most people find a comfortable heat is around 21°C (70°F). Condensation is sure to occur if you let your home fall below 18°C

5. Remove mould as soon as you find it

  • You should remove mould as soon as you find it to stop it spreading and causing more damage to your home. You can get special cleaning products from DIY stores (always follow the manufacturers instructions) or use a good quality bleach mixed 1 part bleach to 4 parts water (but remember bleach may take the colour out).

DO

  • Leave heating on low whenever possible during cold spells
  • Use ventilation fans when cooking or using the bathroom
  • Keep air vents open and clear at all times, especially in bedrooms
  • Clean any black spots with a general household cleaner as soon as they appear

DON’T

  • Dry clothes indoors. All the moisture from the clothes goes in to the air
  • Block air vents – moist air needs to escape
  • Boil food without using a lid or run hot water without using an extraction fan

Page updated on: 03/05/2016

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