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Damp and condensation

Damp can cause mould on walls and furniture and make timber window frames rot. Damp housing encourages the growth of mould and mites and can increase the risk of respiratory illness.
Damp can be caused by leaking pipes, wastes or overflows, rain seeping through the roof where a tile or slate is missing, water spilling from a blocked gutter, penetrating around window frames, or leaking through a cracked pipe or rising damp due to defective damp-course or because there is no damp-course. These causes of damp usually leave a ‘tidemark’.

Keeping your home free from damp and mould

One of the most common causes of damp is condensation, which can be easily avoided in your home. You can usually tell if condensation is the cause of damp in your home because, unlike the causes above, condensation does not leave a tidemark.

By keeping condensation to a minimum in your home, you can reduce the risk of dampness and mould growth.

What is condensation? 

There’s always some moisture in the air, even if you can’t see it.  When the air gets colder it can’t hold all the moisture and tiny drops of water appear. This is condensation.
Condensation occurs mainly during cold weather, whether it is raining or dry. It appears on cold surfaces and in places where there is little movement of air, such as in corners, on or near windows, in or behind wardrobes and cupboards. It often forms on north-facing walls.

How to avoid condensation

There are three things you can do to avoid condensation:
1.     Produce less moisture
Some ordinary daily activities produce a lot of moisture very quickly. By following these simple steps you can produce less moisture in your home:

  • Cover pans and do not leave kettles boiling
  • Avoid paraffin and portable flue less bottled gas heaters as these heaters put a lot of moisture into the air
  • Dry washing outdoors on a line, or in the bathroom with the door closed and the window open or fan on
  • Vent any tumble dryer on the outside, unless it is the self-condensing type. DIY kits are available for this

2.     Ventilate to remove moisture

You can ventilate your home without making draughts:
Keep a small window ajar or a trickle ventilator open when someone is in the room.
Ventilate kitchens and bathrooms when in use by opening the windows wider. Close the kitchen and bathroom doors when these rooms are in use, even if your kitchen or bathroom has an extractor fan. A door closer is advisable, as this will help prevent moisture reaching other rooms, especially bedrooms, which are often colder and more likely to get condensation.
Ventilate cupboards and wardrobes. Avoid putting too many things in them as this stops the air circulating. Cut a ventilation slot in the back of each shelf or use slatted shelves. Cut “breather” holes in doors and in the back of wardrobes and leave space between the back of the wardrobe and the wall. Where possible position wardrobes and furniture against internal walls.

3.      Heat your home 
Always have a low level of background heating, even when there is no one at home.

Some words of warning!

Do not block permanent ventilators.

Do not completely block chimneys. Instead, leave a hole about two bricks in size and fit a louvered grille over it.

Do not draught proof rooms where there is condensation or mould.

Do not draught proof a room where there is a cooker or a fuel burning heater, for example, a gas fire.

Do not draught proof windows in the bathroom and kitchen.

Treatment for mould:

First treat any mould you may already have in your home. If you deal with the basic problem of condensation, mould should not reappear.

To kill and remove mould, wipe down walls and window frames with a fungicidal wash that carries a Health and Safety Executive 'approval number'. Follow the manufacturer's instructions precisely. Dry-clean mildewed clothes and shampoo carpets. Disturbing mould by brushing or vacuum cleaning can increase the risk of respiratory problems.
After treatment, redecorate using a good quality fungicidal paint to help prevent mould recurring. Note that this paint is not effective if overlaid with ordinary paints or wallpaper.
The only lasting way of avoiding severe mould is to eliminate dampness.

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