Damp, mould and condensation
Overview
There are different types of dampness that may affect your home, including:
- Rising damp
- Damp patches (penetrating damp)
- Leaks from plumbing
- Construction damp
- Condensation and mould
Condensation can be the biggest cause of damp in homes. Condensation may be made worse if the other types of dampness are also present.
The information on these pages should help you to identify the various types of dampness and reduce condensation as well as treat the mould growth often associated with it.
View our full Damp, mould, and condensation policy.
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Rising damp
Rising dampness is caused by water rising from the ground into the home. The water gets through or around a defective damp proof course (DPC) or passes through the natural brickwork if the property was built without a DPC.
A DPC is a horizontal layer of waterproof material put in the walls of a building just above ground level. It stops moisture rising through the walls. Rising damp will only affect basements and ground floor rooms. It will normally rise no more than 36 inches above ground level (900mm) and usually leaves a 'tide mark' low down on the wall. You may also notice white salts on the affected areas.
Rising damp will be present all year round but is more noticeable in winter. If left untreated it may cause wall plaster to crumble and paper to lift in the affected area.
Check to see that materials such as soil or building materials, have not been left against the outside of walls as this may allow the dampness to go through / around (bridge) the DPC and cause dampness in the wall. Ideally the DPC will be a minimum of 6 inches (150mm) above ground level.
If the dampness has got around the DPC, try removing the materials as this will allow the walls to dry out. If that doesn't work, a damp proofing specialist will need to be brought in to fix the problem. Tenants should ask their landlord to investigate further.
Mould will rarely be seen where there is rising damp (and then only in the early stages). This is because rising dampness carries with it salts that prevent the growth of mould.
Damp patches (penetrating damp)
This type of dampness will only be found on external walls or, in the case of roof leaks, on ceilings.
It only appears because of a defect in the structure of the home, such as missing pointing to the brickwork, missing roof tiles, loose flashing or leaking gutters.
These defects then allow water to pass from the outside to the inner surfaces. Penetrating dampness is more noticeable after a period of rainfall and will normally appear as a 'damp-patch' which looks and feels damp to the touch. "Tide marks" will be left, even in periods of dry weather.
Mould may be seen on areas of penetrating dampness but not in all cases as the dampness can contain salts picked up when passing through the wall, which may prevent the growth of mould.
If defects are found in the property, a builder will need to carry out the repairs. Tenants should ask their landlord to investigate further.
Leaks from plumbing
Leaks from water and waste pipes, especially in bathrooms and kitchens, are relatively common.
They can affect both external and internal walls and ceilings.
The affected area looks and feels damp to the touch and stays damp whatever the weather conditions outside.
An examination of the water and waste pipes in the kitchen and bathroom and the seals around the bath, shower and sinks will usually find the problem.
If leaks are not repaired, rot may appear in wooden joists and floorboards leading to a risk of collapse in severe cases.
Mould and even fungi may be seen with this type of dampness if the defects are not fixed.
Leaks should be fixed as soon as possible. Tenants should ask their landlord to investigate further.
Construction damp
Sometimes the way a property is constructed or designed can cause damp.
For example:
- properties in areas with a low water table which have suspended timber floors at ground level
- wall ties can fail inside the wall cavity which allows water to penetrate internal walls
Condensation and mould
Condensation is the most common cause of dampness, resulting in a large number of enquiries and complaints received by the 兔子先生.
Condensation is caused by water vapour or moisture in the air, inside the house, coming into contact with a colder surface, such as a window or wall. The drop in temperature causes water to form on the surface. This water may then soak into the wallpaper, paintwork or plasterwork.
Mould spores are invisible to the naked eye but are in the air around us all of the time, and will quickly grow into a visible covering on surfaces where condensation has formed.
Condensation mainly occurs during the colder months, whether it is rainy or dry outside. It is usually found in the corners of rooms, north facing walls and on or near windows. It is also found in areas of little air circulation such as behind wardrobes and beds, especially when they are pushed up against external walls.
Mould is almost always seen with this type of dampness and is normally the first symptom to cause concern.
All homes are affected by condensation at some point, however certain activities can make the problem worse. Good practices can help reduce condensation in your home.
Condensation and mould growth are often due to lifestyle habits and activities that can be reduced or managed better by the householder.
Cooking, washing, drying clothes indoors, even breathing, all produce water vapour that can only be seen when tiny drops of water (condensation) appear on colder surfaces such as walls, windows, ceilings or mirrors and often unseen on clothing, shoes and furniture.
The amount of condensation in a home depends upon a number of things, most importantly:
- how much water vapour is produced by the actions of its residents
- how cold or warm the property is
- how much air circulation (ventilation) there is
- how well the property has been insulated
Simply turning up the heating will not sort out the problem, this may only temporarily reduce condensation. All factors may need to be looked at to reduce the problem.
The first sign of a problem is often water vapour condensing on windows and other cold surfaces, which then takes a long time to disappear. This allows the surfaces to become damp resulting in mould growing on these damp areas.
Mould spores are invisible to the human eye and are always present in the atmosphere both inside and outside of homes. They only become noticeable when they land on a surface upon which they can grow and then multiply.
By dealing with the causes of condensation you will also be dealing with the problem of mould.
Common activities that create moisture
Our everyday activities add extra moisture to the air inside our homes:
- even our breathing adds some moisture. One person asleep adds half a pint of water to the air overnight and an active person adds twice that rate during the day. 2 people at home for 16 hours can add 3 pints
- a bath or shower can add 2 pints
- drying clothes indoors can add 9 pints
- cooking and use of a kettle can add 6 pints
- washing dishes can add 2 pints
- a bottled gas heater (8 hours use) can add 4 pints
How to reduce condensation and mould growth
Following these steps can help to reduce the amount of condensation and mould growth in your home.
Produce less moisture
Ordinary daily activities produce a lot of moisture, to reduce this:
- Dry clothes outdoors if possible. Avoid drying clothes indoors or, if you have to, dry them on a clothes airer in the bathroom with the door closed and either an extractor fan on or with a window open.
- Ventilate tumble driers to the outside (never into the home).
- Cover pans when cooking and turn down to a simmer when they boil.
- Do not use paraffin or liquid petroleum (bottled) gas heaters as they produce large amounts of water vapour.
- Run cold water in to a bath before the hot.
Remove excess moisture
- Wipe the windows and windowsills of your home every morning if water has formed.
- Open windows and turn extractor fans on before running baths and using showers. Ideally extractor fans will be linked to a humidistat that will automatically operate when moisture in the air is high or to the light switch with an overrun when the light is switched off.
- Open curtains to allow for better ventilation and for natural light and heat to enter.
- Clear windowsills of clutter that will restrict opening the windows.
- Leave space between the back of furniture and cold walls. Only place furniture against internal walls if possible.
- Ventilate cupboards and wardrobes and avoid overfilling them as this prevents air circulating.
- Do not completely block chimneys and flues, fit with an air vent to provide constant ventilation.
Heat your home adequately
In cold weather, the best way to keep rooms warm and avoid condensation is to keep low background heat on all day rather than short bursts of high heat when you are in the house.
Try not to turn off the radiators in unused rooms as this could cause dampness and mould growth that you will be unaware of.
Good heating controls on your radiators, room thermostats and a timer will help control the heating throughout your house and help you to better manage costs.
- Insulate and draught-proof. This will help keep your home warm and save money on your heating bills. Insulate the loft up to a depth of 270 mm.
- Consider secondary or double glazing.
- Consider cavity wall insulation.
- Draught-proof windows and external doors. When draught proofing do not block permanent ventilators.
There is support available for help with heating or insulating your home.
Dealing with mould
Mould can grow on walls, ceilings, furnishings and even on clothes and toys, which can be upsetting and expensive to fix.
To kill and remove the mould:
- carefully remove mould with a damp cloth and throw away after. Do not brush mould as this releases spores into the air.
- wipe down the area with a fungicidal wash available from supermarkets and DIY shops, always follow the manufacturer's instructions.
- after treatment, redecorate using a fungicidal paint or wall paper paste. Do not paint over using an ordinary paint.
- dry clean or wash clothes affected by mould and shampoo carpets.
Warmth and ventilation
Getting the right balance between warmth and ventilation is important and can be very effective.
By opening windows or ventilating your home it may appear that you are losing some heat, but this allows warm moisture-laden air to escape and dry air to enter your home.
Many people who have double-glazing installed experience problems with condensation and mould growth that they never had with their old draughty window frames. This is because all the natural draughts around the poorly fitted windows have been sealed. However, by using trickle vents or opening windows slightly, then the necessary ventilation level can be achieved.
Ventilation needs to be provided for an appropriate amount of time depending on how much water you produce in the home and on weather conditions.
On a warm, dry day a home should be ventilated to the maximum. On a cold wet day ventilation may not be of any help except in a bathroom or kitchen where most water is produced.
It should not be necessary to leave all windows open all day.
Dealing with condensation is not always easy. Only carrying out one or two of the above steps may not solve your problem.
You need to do as many as possible every day, so that they become part of your habits and lifestyle.
Other things like making sure windows are fitted correctly and the seals are in-tact can help to reduce cold spots and the appearance of condensation mould.
Who is responsible for problems with damp in your home
In many cases, your landlord is responsible for dealing with damp. This is because there's a term implied into your tenancy agreement which says that it's their responsibility to keep the exterior and structure of your home in good repair.
Structural problems in your property that cause damp, penetrating damp or plumbing / construction damp will usually be the responsibility of the landlord, however this is not necessarily the case when it comes to condensation.
Condensation in the home can often build up and cause damp because of the things we do, for example
- blocking ventilation points (air vents)
- drying clothes on radiators
- not using / switching off extraction fans
- failing to ventilate our homes sufficiently to get rid of moisture
If you are not using your home in a reasonable way or failing to keep on top of any build-up of condensation on windows and walls, then this can lead to damp and mould growth in the property, which the landlord is not likely to be responsible for fixing.
Your landlord is likely to be responsible if:
- If the damp was caused by your landlord not making specific repairs, for example failing to fix your boiler / heating system
- the damp has caused damage to things in your property that the landlord is responsible for repairing, for example rotten window frames
If you feel your home isn't safe to live in because of damp, i.e it is making you or your family ill, then your landlord might be responsible. You should contact your landlord immediately, see How to report a repair.
If you have reported damp to your landlord and can show that you have contacted them about the problem already, but they haven't done anything about it, then please get in touch with us.
Contact the Private Sector Housing Team by:
Help with heating or insulating your home
There is help and support that you may be able to access to help with heating and insulation improvements:
Further help and support to help with cost of living pressures is available, see Cost of Living and welcoming places.