Damp and mould
The advice on this page mainly deals with condensation and mould growth resulting from everyday living. Condensation and mould growth can be caused, or made worse, by defects in the home.
If there is insufficient or no fixed heating, or the property lacks insulation, or there is cold-bridging, these can all make condensation more likely and more severe. Conditions such as these should be reported to the Private Sector Housing team, especially if you live in private rented accommodation.
Damp and mould
Damp can be really hard to deal with, especially during the winter months and it is not unusual for properties to show signs of condensation and mould. This is made even worse as the weather gets colder.
Condensation is a very common form of damp where moisture generated through everyday living condenses on cold surfaces.
Other forms of damp include:
- Penetrating damp - where damp penetrates through the walls of the building and can usually be seen as an area of 'wet' staining on the wall or ceiling.
- Rising damp - where there is a failure in the damp proof course and moisture rises up through the building from the ground. This will only affect the ground floor as moisture cannot rise above 1 metre and will show as a 'tide' mark.
For advice on dealing with condensation and mould please take a look at our:
You can also download a leaflet produced by the Private Sector Housing Team.
Damp and Mould: Top tips to reduce the problem
Damp and mould is often the result of water vapour condensation on cold surfaces. This type of mould looks like “black spots” and is typically found in corners, behind furniture, along skirting boards or ceiling edges.
Heat:
Heating one room to a high level and leaving other rooms cold makes condensation worse in the unheated rooms. Try to leave some background heat on throughout the day in cold weather. Most dwellings take quite a long time to warm up, and it may cost you more if you try to heat your home up quickly in the evening. If you don't have heating in every room, you could keep the doors of unheated rooms open to allow some heat into them.
To add extra heat to rooms without any form of fixed heating, it is better to use electric heaters, for example oil-filled radiators or panel heaters, on a low setting. Try not to use portable bottled gas heaters in homes suffering with condensation as they give out a lot of moisture whilst in use.
Ventilate:
Ventilation is essential. We suggest using 'flush ventilation' to deal with moisture that has built up overnight. Open the windows in a couple of rooms every morning to allow a through draught for 20-30 minutes. They should be on opposite sides of the house, or diagonally opposite if you live in a flat. Don't forget to then close the windows to allow the property to be heated properly.
Always open the bathroom window after you bath or shower and leave it open until the mirror is no longer steamed up (Keep the bathroom door closed though).
When cooking, open a window so the excess moisture can escape.
If you have extractor fans fitted, use it when cooking or having a bath/shower and keep it running for a while after you have finished.
Allow air to circulate around stored clothes.
Keep a small gap between large pieces of furniture and the walls, and where possible place wardrobes and furniture next to internal walls instead of external ones.
Pull shelves away from the backs of wardrobes and cupboards and try not to overfill wardrobes and cupboards as it restricts air circulation.
If placed against an outside wall, regularly move the furniture so that you can clean behind it.
Reduce water vapour in your home:
Drying clothes indoors, particularly on radiators, can increase condensation unless you open a window to allow air to circulate.
Hang your washing outside to dry if at all possible, or hang it in the bathroom with the door closed and a window slightly open or extractor fan on.
If you have a tumble dryer which is not vented to the outside you will need to allow more ventilation when you use it.
Always cook with pan lids on, and turn the heat down once the water has boiled. Only use the minimum amount of water for cooking vegetables.
Remove existing mould:
Existing mould can be removed by wiping down walls and window frames with a fungicidal wash that carries a Health and Safety Executive (HSE) approval or by using a diluted bleach solution, as detailed in our leaflet.
Don't forget to follow the instructions on the label.
Warning - most fungicidal washes are designed for use on hard surfaces (such as tiles, or splashback), not plastered, painted or papered walls. Using these washes on the wrong surface can add moisture and make the mould problem worse.
Remember:
The most important action to control condensation and mould growth is to improve ventilation and maintain low level background heating.
Damp and mould: Frequently asked questions (FAQs)
How do I know if it is condensation?
It is not always easy to tell but here are some key differences between condensation and other forms of damp.
Condensation is usually found on external walls (especially colder, north-facing walls) and in corners, in cupboards and under work surfaces - in fact wherever there is relatively limited air movement.
Other kinds of dampness, such as penetrating damp from rain or plumbing leaks or rising damp, usually leave a 'tidemark'.
In general, condensation can often be characterised by mould growth, which is less common from penetrating or rising damp.
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What could be causing the damp in my home?
If you are not sure what is causing the damp in your home, start by checking pipes and overflows and under sinks to see if there are any obvious leaks. Have a look outside, too - you may be able to see if there are slates missing from the roof or cracked gutters or rainwater pipes.
If you live in a new or recently modernised house or flat, don't forget that it may not have dried out from the water remaining after the building work. It usually takes 9 to 18 months for this to happen and you may need to use more heat during that time.
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Why am I getting condensation and mould growth?
Every home gets condensation at some time - usually when lots of moisture and steam are being produced, for instance at bath-times, when a main meal is being cooked or when clothes are being washed. It is quite normal to find your bedroom windows misted up in the morning after a cold night, for example.
Air can only hold a certain amount of water vapour - the warmer it is, the more it can hold. If air is cooled by contact with a cold surface such as a mirror, a window or even a wall, the water vapour will turn into droplets of water-condensation.
Heating your home is not just about your thermal comfort, it also makes it less likely for you to get condensation.
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Why does mould appear?
Typically, black mould needs some moisture on a relatively cold surface in an area of low relative air movement in order to grow. Black mould spotting is when the colonies of black mould growth are sufficiently large to be seen. They will often be seen in the corners of window reveals, or ceilings and skirting boards.
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Is dampness, condensation and mould bad for my health?
It depends - penetrating damp tends to damage the fabric of the property, but will not directly affect your health. Condensation is just water droplets.
However, if your property has penetrating damp (which will affect thermal insulation) and/or has lots of condensation, it is likely that it is a cold home and living in a cold home will lead to negative health effects, especially for older people. Therefore it is important to keep your house warm.
Mould and fungi can be allergenic, but the conditions that give rise to mould growth also promote the growth of house dust mites, which are the most common triggers of asthma.
Mould and fungi can affect your health, especially psychologically, as black mould growth is unpleasant to see and have in your home. Mould is more likely to make sick people sicker, particularly if the amount of mould growth is allowed to become excessive
You should use ventilation and heating to discourage mould growth and also clean areas where mould appears on a regular basis.
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What can I do to get rid of mould?
Existing mould can be removed by wiping down walls and window frames with a fungicidal wash that carries a Health and Safety Executive (HSE) approval or by using a diluted bleach solution, as detailed in our leaflet.
Don't forget to follow the instructions on the label.
Warning - most fungicidal washes are designed for use on hard surfaces (such as tiles, or splashback), not plastered, painted or papered walls. Using these washes on the wrong surface can add moisture and make the mould problem worse.
Dry-clean mildewed clothes, and shampoo carpets. Do not try to remove mould by using a brush or vacuum cleaner.
After treatment, and where appropriate, redecorate using good-quality fungicidal paint and a fungicidal resistant wall paper paste to help prevent mould recurring. The effect of fungicidal or anti-condensation paint is destroyed if covered with ordinary paint or wallpaper.
The most effective treatment is to reduce the amount of condensation in your home. Remember, the way you use your home affects the amount of condensation you get. This does not mean that you should alter your habits drastically - just bear in mind the following tips:
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Can my gas boiler be to blame?
This is unlikely - bottled gas heaters (Calor) produce a lot of moisture and will make condensation worse, but a correctly operating central heating gas boiler will not contribute to excessive moisture in the home.
Your gas boiler must be checked on a regular basis by a registered Gas Safe engineer to make sure it is safe and working efficiently.
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What can I do to help reduce my energy costs?
You will get less condensation if you keep your home warm most of the time. This is not easy with fuel prices so high, but try to remember the following:
- Heating one room to a high level and leaving other rooms cold makes condensation worse in the unheated rooms.
- Try to leave some background heat on through the day in cold weather.
- Most dwellings take quite a long time to warm up, and it may cost you more if you try to heat it up quickly in the evening.
- If you don't have heating in every room, you could keep the doors of unheated rooms open to allow some heat into them.
The Debt Advice Foundation can give you advice on financial worries relating to fuel bills. For more information please see:
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What heaters should I use?
To add extra heat to rooms without any form of heating, it is better to use electric heaters, for example oil-filled radiators or panel heaters, on a low setting. Try not to use portable bottled gas heaters in homes suffering with condensation as they give out a lot of moisture whilst in use. Contrary to popular belief, it is actually cheaper to heat a room with on-peak electricity than by bottled gas heaters.
If you use bottle gas and paraffin heaters you will need to allow extra ventilation. Flueless heaters of this sort produce more than a pint of water for every pint of fuel they burn. So, using a bottled gas heater for 8 hours would produce around 4 pints of moisture.
Don't use your gas cooker to heat your kitchen as it produces moisture when burning gas. (You might notice your windows misting over).
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Will insulating my home make a difference?
Condensation forms more easily on cold surfaces in the home, insulation and draught proofing can help keep your home warmer.
Loft and wall insulation are the most effective forms of insulation.
If you use draught proofing remember that you should not block permanent ventilators or air bricks and do not draught proof kitchen or bathroom windows.
You may be eligible for financial assistance for insulation and heating. More information on the Green Deal scheme can be found at the following webpage:
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How can I dry my clothes without making condensation worse?
Drying clothes indoors, particularly on radiators, can increase condensation unless you open a window to allow air to circulate.
Up to 9 pints of excess water can be produced by drying your clothes inside.
Hang your washing outside to dry if at all possible, or hang it in the bathroom with the door closed and a window slightly open or extractor fan on.
Don't be tempted to put it on radiators or in front of a radiant heater.
If you have a tumble dryer which is not vented to the outside you will need to allow more ventilation when you use it.
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How can I reduce condensation when bathing?
When filling your bath, run the cold water first then add the hot - it will reduce the steam by 90% which leads to condensation.
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How can I stop my clothes from getting mouldy in cupboards and wardrobes?
Don't overfill cupboards and wardrobes. Always make sure that some air can circulate freely by fitting ventilators in doors and leaving a space at the back of the shelves.
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Will blocking my chimney make a difference?
Never block these up completely. If you are blocking up a fireplace, fit an air vent to allow ventilation.
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Should I keep my kitchen and bathroom doors open or closed?
Keep kitchen and bathroom doors shut, particularly when cooking, washing or bathing - otherwise water vapour will spread right through the house and condensation will probably reach other rooms.
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What is the best way to ventilate my home?
The more moisture produced in your home, the greater are the chances of condensation, unless there is adequate ventilation. Nobody likes draughts, but some ventilation is essential.
We suggest using 'flush ventilation' to deal with moisture that has built up overnight. Open the windows in a couple of rooms every morning to allow a through draught for 20-30 minutes. They should be on opposite sides of the house, or diagonally opposite if you live in a flat. Don't forget to then close the windows to allow the property to be heated properly.
Always open the bathroom window after you bath or shower and leave it open until the mirror is no longer steamed up (Keep the bathroom door closed though).
When cooking, open a window so the excess moisture can escape.
If you have extractor fans fitted, use it when cooking or having a bath/shower and keep it running for a while after you have finished.
Reduce the risk of mildew on clothes and other stored items by:
- allowing air to circulate round them
- remove 'false' wardrobe backs or drill breather holes in them
- place furniture on blocks to allow air to circulate underneath
- keep a small gap between large pieces of furniture and the walls
- where possible place wardrobes and furniture next to internal walls instead of external ones
- pull shelves away from the backs of wardrobes and cupboards
- never overfill wardrobes and cupboards as it restricts air circulation
Do not install air bricks as this is uncontrolled ventilation, which makes it difficult to achieve the right balance of heating and ventilation to reduce condensation.
Important notes:
- Make sure that accessible windows may cause a security problem - remember to close windows when you go out.
- If you have an extractor fan use it when cooking or having a bath /shower to stop the windows getting steamed up and keep it running for a while after you have finished.
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Can how I cook make a difference?
Don't allow kettles and pans to boil away any longer than is necessary.
Always cook with pan lids on, and turn the heat down once the water has boiled. Only use the minimum amount of water for cooking vegetables.
Keep the kitchen door closed when cooking and make sure you use the mechanical extract ventilation.
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What are the key points to remember to control condensation?
Try to reduce the amount of moisture you produce - see:
- Can how I cook make a difference?
- How can I dry my clothes without making condensation worse?
- How can I reduce condensation when bathing?
- Should I keep my kitchen and bathroom doors open or closed?
Improve ventilation in your home - see:
- What is the best way to ventilate my home?
- Will blocking my chimney make a difference?
Try to maintain an adequate temperature throughout your home.
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What if I need further help?
If you are having problems with damp or excessive condensation in your home then you can contact the Private Sector Housing Team for further advice using the form below:
01273 263098
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Page last updated: 25 November 2022