15 November 2023

Damp and Mould



What is damp?

Dampness in your home can be caused by a number of things.

Plumbing leaks from water and waste pipes, from broken seals around the bath or shower tray or leaking appliances.

Penetrating damp rain water seeping through the roof where a tile or slate is missing, spilling from a blocked gutter or leaking downpipe, around window frames or leaking through a cracked pipe.

Rising damp when moisture travels up from the ground through the floor and walls. This only appears at ground level and is usually seen by a damp stain up to the height of about one metre due to a defective damp-course or because there is no damp-course.

Construction damp if there is a design fault creating cold spots or if your home is newly built it may be damp because the water used during its construction for example, in the plaster is still drying out.

If your home is damp for any of these reasons, once the source of dampness has been removed it may take weeks of heating and ventilation to dry it out, using a dehumidifier will help.

If you do not think the damp comes from any of these causes, then it is probably condensation.

  1. Too much moisture in the air
  2. Not enough ventilation
  3. Insufficient heating
  4. Poor insulation

If there is too much condensation in your home and it’s not dealt with properly, it can lead to mould on walls, mildew on curtains and fabrics and the growth of mites all of which can harmfully affect the health of people with asthma, allergies and breathing conditions.

Condensation mainly occurs during cold weather and it tends to appear on cold surfaces and walls where there is little movement of air, such as in the corners of rooms, near windows or behind furniture.


What is condensation?

Condensation is caused by moisture in the air (humidity). The more humid the air is in your house the more energy it takes to warm your house and the more expensive it will be to heat. There is always some moisture in the air, even if you can’t see it.

When air gets colder it can’t hold all the moisture and tiny drops of water appear – this is condensation.

You may notice it when you see your breath on a cold day, or when the bathroom mirror mists over when you have a bath or shower.

What causes condensation?

You are producing moisture all the time, simply by breathing.

Day to day activities such as cooking, having a bath or shower, washing and drying clothes also produce moisture in your home:

The three main causes of condensation are:

How to reduce condensation?

There are some simple steps to help reduce the amount of condensation in your home.

Reduce the amount of moisture in the air by:

  • On dry days open some windows or trickle vents to allow humid air to ventilate out of the house.
  • Use extract fans in the kitchen and bathrooms, better still a humidistat-controlled electric fan operates automatically when the air becomes humid and are cheap to run.
  • Putting lids on saucepans
  • Drying clothes outside or in a tumble dryer. If you must dry clothes inside make sure it’s in a heated & well-ventilated room, with the doors closed to the rest of the house.
  • Make sure your tumble dryer is vented outside unless it is a condensing model.
  • Don’t dry washing on radiators.
  • Open the window when ironing.
  • Adding cold water to the bath first to create less steam.
  • Don’t use portable gas heaters as they produce large amounts of water vapour, are expensive to run and may also release harmful gases into the air.
  • Always wipe excess moisture from windows – if you don’t the moisture will collect on the frame which may start to rot. It may also re-evaporate during the day, raising humidity levels and making condensation worse when the room cools down.
  • Dehumidifiers extract moisture from the air and can help reduce humidity. However, they do not tend to solve underlying problems of moisture getting into your house, excess moisture production in the home, and lack of ventilation and heating.

Ventilate to remove moisture:

  • Close kitchen and bathroom doors when cooking or bathing to prevent the spread of moisture.
  • Use cooker hoods and extractor fans if you have them (the typical running costs are just £2-£5 per year) or open a window when cooking or bathing
  • Don’t block air vents.
  • Move furniture away from walls to allow air to circulate (you may need to move large items of furniture such as wardrobes and beds away from outside walls).
  • Don’t overfill cupboards or wardrobes.

Heat your home:

  • Maintain constant heat throughout your house, on cold days try to keep indoor temperatures between 18-21°C.
  • Low heating on during the day rather than quick blasts of high heat should also reduce your heating bills. If you heat one room to a high temperature but leave others cold condensation will be worse in the unheated cold rooms.
  • Use thermostats to control your heating.
  • It may take some time and trial and error before you can effectively manage the condensation levels in your home.

Insulation and draughtproofing:

  • Insulate you loft to a depth of at least 270mm. Remember to draughtproof the loft hatch but do not block the opening under the eaves.
  • Consider cavity wall insulation.
  • Consider secondary and double glazing of windows to reduce heat loss and draughts but you must ensure that there is some ventilation.
  • Avoid draughtproofing rooms where there is condensation or mould growth; rooms where there is a gas cooker or a fuel-burning heater and the windows in the bathroom or kitchen.


Mould spores are invisible to the human eye and are always present in the atmosphere both inside and outside dwellings. They only become noticeable when they land on a surface upon which they can grow and then multiply.

For mould to thrive and survive it requires four elements

  • Moisture - from condensation
  • Food - such as wallpaper or emulsion paint
  • Suitable temperature - heating
  • Oxygen- from air

 How to treat mould?

 Use a fungicidal wash to clean affected walls, ceilings and paintwork. These are sold in supermarkets and DIY stores. Make sure you buy one with a Health & Safety Executive (HSE) approval number and follow the manufacturer’s instructions. Throw away any cloths you have used to clean the mould.

  • Empty cupboards and wardrobes that have been affected by mould and thoroughly clean all the contents.
  • Try to avoid disturbing mould by brushing or vacuuming because this can increase the risk of breathing problems.
  • Dry-clean mildewed clothes and shampoo affected carpets.
  • Once you have successfully eliminated the mould, redecorate using fungicidal paint and fungicidal wallpaper paste.
  • Treat any mould you may already have in your home then do what you can to reduce condensation. This will restrict new mould growth.
Hayden Grant – Veteran

I am grateful to the support given by Veterans Housing Scotland; the charity has really helped in improving the lives of my family and given us a chance to build a decent future.

Hayden Grant – Veteran, Royal Regiment of Scotland