Your Home

Damp and Mould

Some damp is caused by condensation. This factsheet explains how to reduce the risk of dampness and mould growth.

Keep your home free from damp and mould factsheet

Is your home damp?

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. Some damp is caused by condensation. This page explains how condensation forms and how you can keep it to a minimum, so reducing the risk of dampness and mould growth.

First steps against condensation

You will need to take proper steps to deal with the condensation, but meanwhile there are some simple measures you can take right away. Wipe down the windows and sills every morning. Wring out the cloth rather than drying it on a radiator. Condensation channels and sponge strips can be bought at DIY shops. They are fitted to windows to collect the condensation and thus help prevent window frames from rotting and avoid damp forming under sills. Care must be taken to fit these devices properly.

First steps against mould

First treat the mould already in your home. If you then 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 which carries a Health and Safety Executive ‘approval number’. Follow the manufacturers’ 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. 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.

Is it condensation?

Condensation is not the only cause of damp. It can also come from:

  • leaking pipes, wastes or overflows;
  • rain seeping through the roof where a tile or slate is missing, spilling from a blocked gutter, penetrating around window frames, or leaking through a cracked pipe;
  • rising damp due to a defective damp-course or because there is no dampcourse

These causes of damp often leave a ‘tidemark’. If your home is newly built it may be damp because the water used during its construction (for example, in plaster) is still drying out. If your home is damp for any of these reasons it may take weeks of heating and ventilating to dry out. Hiring a dehumidifier will help. If you do not think the damp comes from any of these causes, it is probably condensation.

What is condensation?

There is always some moisture in the air, even if you cannot see it. If the air gets colder it cannot hold all the moisture and tiny drops of water appear. This is condensation. You notice it when you see your breath on a cold day, or when the mirror mists over when you have a bath. Condensation occurs mainly during cold weather, whether it is raining or dry. It does not leave a ‘tidemark’. It appears on cold surfaces and in places where there is little movement of air. Look for it in corners, on or near windows, in or behind wardrobes and cupboards. It often forms on north-facing walls.

How to avoid condensation

These four steps will help you reduce the condensation in your home.

  1. Produce less moisture - Some ordinary daily activities produce a lot of moisture very quickly. 
    1. Cooking: To reduce the amount of moisture, cover pans and do not leave kettles boiling.
    2. Paraffin and portable flueless bottled gas heaters: These heaters put a lot of moisture into the air - one gallon of gas or paraffin produces about a gallon of water vapour. If you have a problem with condensation, try to find an alternative means of heating.
    3. Washing clothes: Put washing outdoors to dry if you can. Or put it in the bathroom with the door closed and the window open or fan on. If you have a tumble dryer make sure you vent it to the outside (unless it is the self-condensing type). DIY kits are available for this.
  2. Ventilate to remove the moisture

You can ventilate your home without making draughts. Some ventilation is needed to get rid of moisture being produced all the time, including that from people’s breath. Keep a small window ajar or a trickle ventilator open when someone is in the room. You need much more ventilation in the kitchen and bathroom when cooking, washing up, bathing and drying clothes. This means opening the windows wider. Better still, use a humidistat-controlled electric fan (these come on automatically when the air becomes humid, and are cheap to run). 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. Doing this will help stop the moisture reaching other rooms, especially bedrooms, which are often colder and more likely to suffer condensation. Ventilate cupboards and wardrobes. Avoid putting too many things in them, as that 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.
Leave space between the back of the wardrobe and the wall. Put floor-mounted furniture on blocks to allow air underneath. Where possible, position wardrobes and furniture against internal walls (walls which have a room on both sides) rather than against outside walls. If you replace your window units at any time, make sure that the new frames incorporate trickle ventilators.Insulate and draughtproof

  1. 3. Insulation in the loft, cavity wall insulation and draughtproofing of windows and outside doors will help keep your home warm and you will have lower fuel bills as well. When the whole home is warmer, condensation is less likely.

When draughtproofing:

  • do not block permanent ventilators;
  • do not completely block chimneys (leave a hole about two bricks in size and fit a louvred grille over it);
  • do not draughtproof rooms where there is condensation or mould;
  • do not draughtproof a room where there is a fuel-burning heater (for example, a gas fire) or cooker;
  • do not draughtproof windows in the bathroom and kitchen.

If you live in a house, insulating your loft is a cost-effective way of cutting heating costs. Remember to draughtproof the loft hatch but do not block the opening under the eaves. Cavity wall insulation is also an effective way of cutting heating costs. Before deciding on this method of insulating, however, you should talk to your local building inspector as building regulations approval is required. Secondary and double glazing of windows reduces heat-loss and draughts but you must ensure that there is some ventilation. Heat your home a little more

  1. 4. In cold weather, the best way to keep rooms warm enough to avoid condensation is to keep low background heating on all day, even when there is no one at home. This is very important in flats and bungalows and other dwellings where the bedrooms are not above a warm living room. So if possible, install a very small heater with a thermostat in each bedroom (but do not use a paraffin or flueless bottled gas heater for this purpose). The thermostat will help control heating and costs.

Dehumidifiers will help dry out damp in newly built houses. They can also help reduce condensation in warm rooms with a lot of moisture, but they are of little use in cold damp rooms.

Points to remember

Produce less moisture:

  • cover pans
  • dry clothes outdoors
  • vent your tumble dryer to the outside
  • avoid using paraffin or flueless bottled gas heaters

Ventilate to remove moisture:

  • ventilate when someone is in
  • increase ventilation of the kitchen and bathroom when in use and shut the door
  • ventilate cupboards, wardrobes and blocked chimneys

Insulate and draughtproof:

  • insulate the loft
  • draughtproof windows and external doors
  • consider cavity insulation
  • consider secondary glazing
  • find out if you are eligible for a grant or other help

Heat your home a little more:

  • if possible, keep low background heat on all day
  • find out about benefits, rebates and help with fuel bills

If you have followed the guidelines in the factsheet and the problems persists please contact Building maintenance on 0800 085 6622

You can report a repair by phone during these times:

8.00 am to 6.00 pm Monday to Thursday
8.00 am to 5.00 pm Friday
8.00 am to 2.00 pm Saturday and Sunday

Out of hours emergencies can be reported by phoning 01437 775522

To report a repair:

  • Phone the Housing Repairs Hotline on 0800 085 6622
  • Call in at a Council Customer Services Centre located at Haverfordwest, Pembroke Dock, Milford Haven, Fishguard or the cash desk in Neyland
  • By e-mail to buildingmaintenance@pembrokeshire.gov.uk
  • By Fax on 01437 775911
  • Write to us: Pembrokeshire County Council, Maintenance Department, Unit 23, Thornton Industrial Trading Estate, Milford Haven, SA73 2RR
ID: 1760, revised 13/09/2022
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