Damp can cause mould on walls, furniture and rot window frames, and it can increase the risk of respiratory illnesses, such as asthma.
It is often caused by condensation.
About condensation
When air gets colder, it cannot hold all the moisture it contains and tiny drops of water appear. This is condensation.
It occurs mainly during the winter because a building is cold and windows are opened less, meaning moist air cannot escape.
It can occur in one part of a building and move to another area as the moisture will pass to the colder parts.
Condensation can also come from:
- leaking pipes, wastes or overflows
- when rain leaks through a building
- defective damp proofing course (or where there is no damp course)
These causes of damp usually leave a tidemark.
If the home is damp for any of those reasons it may take weeks of heating and ventilation to dry out.
Newly built homes may be damp because the water used during its construction is still drying out.
If the problem is due to any of these causes, then it is likely to be part of the landlords repairing responsibilities. If you do not think the damp comes from any of these causes, then it is probably condensation.
How to avoid condensation
Produce less moisture
Daily activities can produce a lot of moisture, so it is good to:
- cover pans
- avoid drying clothes on radiators
- vent tumble dryers on the outside
Ventilate
Homes can be ventilated without making draughts:
- open bedroom windows in the morning
- ventilate kitchens and bathrooms when in use by opening the windows
- close kitchen and bathroom doors when these rooms are in use, even if your kitchen has an extractor fan (closed doors help prevent moisture reaching other rooms)
- use permanent vents
Heating
Central heating is usually the best form of heating.
If heating is not used enough the structure will not heat up and leave it vulnerable to condensation problems.
In cold weather, keep low background heating on all day, even when there is no one at home.
Avoid heaters that do not warm up the structure.
Insulate and draughtproof
When the whole home is warmer, condensation is less likely.
Insulation and draughtproofing will help keep homes warm and will also cut fuel bills.
You should not draughtproof windows in the bathroom and kitchen and rooms where there is condensation or mould.
Things you can do:
- use double glazed windows, which reduce heat loss and draughts
- insulating lofts - most houses will have less insulation than the standard of 270mm unless improved recently (loft hatches need draughtproofing, but do not block the opening under the eaves)
- insulate gaps between the joists in a cellar where cellar ceilings have been removed
- cavity wall insulation is a good improvement for post-1920s houses
- insulated plasterboards on internal walls are good for houses without cavity walls
Avoiding mould
The only lasting way of avoiding severe mould is to eliminate dampness.
If the landlord has provided correct levels of insulation, suitable heating and ventilation then it will usually be the responsibility of the tenant to treat for mould.
To kill and remove mould:
- wipe down walls and window frames with a fungicidal
- the wallpaper will then need to be removed in the affected area
- it should be replaced only after the condensation has been eliminated and a fungicidal wallpaper paste should be used
- after treatment, redecorate using a good quality fungicidal paint to help prevent mould recurring
Be careful when handling mould: disturbing mould by brushing or vacuum cleaning can increase the risk of respiratory problems, which can be caused or made worse through mould.
You can also shampoo carpets and dry–clean mildewed clothes to avoid mould.
Moisture build up and carbon monoxide
To avoid build up of moisture and to help reduce chances of carbon monoxide poisoning:
- do not block permanent ventilators
- do not completely block chimneys - leave a hole about two bricks in size and fit a louvered grille over it
- rooms with gas or solid fuel fires, cookers or boilers require adequate ventilation, so do not draughtproof in these rooms