Mould - The Basics


The key to managing condensation and mould in your home is about getting the right balance between moisture in the air and heating and ventilating your home so that you can keep condensation to a minimum. Changes in temperature, lots of moisture and no ventilation will cause more condensation to form. Having a more constant temperature, reducing moisture and having good ventilation will reduce condensation.

Ventilating your home

To keep condensation at bay it is essential that you ventilate your home to enable the moisture-rich humid air to escape and allow fresh air in:

  • Reduce the condensation that builds up overnight by cross ventilating your home. You can do this by opening a small window to the first notch and a small one-window diagonally to the opposite. So open the kitchen window and the sitting room window At the same time, open the internal doors, as this allows drier air to circulate. Do this for approximately 40 minutes each day.
  • Ventilate your kitchen when cooking, washing up or washing by hand. A window slightly open for a long period is as good as a window wide open for a short period. If you have a cooker extraction hood or extraction fan use it to remove steam before it circulates throughout your home.
  • Ventilate your kitchen and bathroom for about 20 minutes after use by opening a small top window. Use an extraction fan.  Keep kitchen and bathroom doors closed when in use to prevent moisture escaping into the rest of the house.
  • Ventilate your bedroom by leaving a window slightly open at night or use trickle ventilators if fitted. Reduce the risk of mildew on clothes by allowing air to circulate around them. You can do this by leaving a small gap between large pieces of furniture and where possible place wardrobes and furniture against internal walls not external walls.
  • Never overfill wardrobes and cupboards as it restricts air flow. Do not push beds and sofas against outside walls which are always colder and attract condensation. Make sure there is a 9 inch (225mm) gap. Bedding can get damp if air cannot circulate around it.
  • Please note : Do not over ventilate your home in cold weather as this will reduce the temperature inside making condensation more likely as well as increasing heating costs. Remember that it is about creating the right balance for your home.
  • Please ensure you close windows securely before you go out.

Heating your home

By keeping your home warm you will also warm the walls and surfaces of your home. A combination of warm air and warm surfaces will allow more moisture to stay in the air within your home and will reduce the extent of condensation you experience:

  • If possible try to keep your home at a constant temperature rather than heating your home from cold twice a day
  • Heating one room to a high level and leaving other rooms cold makes condensation worse in the unheated rooms. It is better to have a constant level of heat throughout your home
  • do not push beds or sofas against radiators as this prevents efficient circulation of warm air.

Moisture in your home

Everyday living adds extra moisture to the air inside your home, even breathing contributes to the amount of water in the air. One sleeping person adds half a pint of water to the air overnight and twice that when active in the day.

The following table shows how much extra water you add to the air inside your home on a daily basis:

  1. Two people at home (breathing), 3 pints
  2. One bath or shower, 2 pints
  3. Drying clothes indoors, 9 pints
  4. Cooking and using a kettle, 6 pints
  5. Washing dishes (by hand), 2 pints

Your home cannot cope with this additional water being continually added to the air without condensation forming. The water you and your family adds to the air can be easily reduced if you:

  • hang your washing outside to dry if at all possible, or hang it in the bathroom or spare room with the door closed and the window open or an extraction fan on. Do not put washing on radiators or in front of radiant heaters.
  • if you use a tumble drier, make sure it is vented to the outside or that it is the new condensing type
  • 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
  • do not use your gas cooker to heat your kitchen as burning gas produces more moisture (you will notice your windows mist over)
  • when filling your bath, run the cold water first and then add hot, it reduces steam (which leads to condensation) by 90%.
  • control moisture in the home by having some of the following plants in each room
    • English Ivy
    • Catus
    • Boston Fern -  Said to act as a natural air humidifier, removes formaldahyde and is a general air purifier. Said to be among the best in air purifying houseplants.
    • Peace Lily - Known for removing benzene, a common household chemical and known carcinogen. It's also said to remove mold spores in the air, making it great for bathrooms, kitchens and laundry rooms.

Striking the right balance

Getting the balance right for you and your home is an ongoing process. During this process you will experience some form of condensation and you will have to take action to stop the condensation an mould becoming a problem.

Mould growth will develop on walls, furnishing, and clothes once dampness is present for a period of time. Mould fungus needs three conditions to grow (infection, nourishment and a damp environment) and these will be present in a dwelling once a damp environment is established for a period of time.


When condensation occurs wipe your wet windows and window cills every morning, as well as any wet surfaces in the kitchen or bathroom. Wring out the cloth and dry it outside rather than drying it on a radiator.

When condensation is left untreated mould will develop. To kill and remove mould;

  • wipe down or spray walls and window frames with a fungicidal wash that carries a Health and Safety Executive (HSE) approval number and follow the instructions carefully for safe use. You can often buy these in supermarkets.  We use HG mould cleaner, it always seems to do the trick and can be purchased online or at B&Q.  Please note that this item comes with possible health and safety hazards. Refer to the container for full information and always follow the instructions.
  • A natural fungicide is tea tree oil.  It can eliminate your nasty mould or mildew problems. Plus, it will fill your home with a lovely medicinal scent. Simply add 10 drops of tea tree oil to a spray bottle and fill it with water. Spray the mixture on mouldy problem areas. Let the mixture sit and then wipe away the mould.
  • After treatment, redecorate using a good fungicidal paint and a fungicidal resistant wall paper paste to help prevent mould growth recurring. It should be noted that the affect of fungicidal or anti-condensation paint is destroyed if covered with ordinary paint or wallpaper.

Why is mould growing in my home?

Moulds are part of the natural environment. Outdoors, moulds play a part in nature by breaking down dead organic matter such as fallen leaves and dead trees, but indoors, mould growth should be avoided. Moulds reproduce by means of tiny spores; the spores are invisible to the naked eye and float through outdoor and indoor air. Mould may begin growing indoors when mould spores land on surfaces that are wet. There are many types of mould, and none of them will grow without water or moisture.

Can mould cause health problems?

Moulds are usually not a problem indoors, unless mould spores land on a wet or damp spot and begin growing. Moulds have the potential to cause health problems. Moulds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mould or mould spores may cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mould are common. They can be immediate or delayed. Moulds can also cause asthma attacks in people with asthma who are allergic to mould. In addition, mould exposure can irritate the eyes, skin, nose, throat, and lungs of both mould-allergic and non-allergic people. Symptoms other than the allergic and irritant types are not commonly reported as a result of inhaling mould. Research on mould and health effects is ongoing.

How do I get rid of mould?

It is impossible to get rid of all mould and mould spores indoors; some mould spores will be found floating through the air and in house dust. The mould spores will not grow if moisture is not present. Indoor mould growth can and should be prevented or controlled by controlling moisture indoors. If there is mould growth in your home, you must clean up the mould and fix the water problem. If you clean up the mould, but don't fix the water problem, then, most likely, the mould problem will come back.

Mould Clean-up

Who should do the clean-up depends on a number of factors. Mould in properties tends to be caused by the way you are living in the property therefore its usually the tenant who is the person responsible for the clean up. Another consideration is the size of the mould problem. If the mouldy area is less than about 10 square feet (less than roughly a 3 ft. by 3 ft. patch), in most cases, you can handle the job yourself.

If you already have a mould problem - ACT QUICKLY. Mould damages what it grows on. The longer it grows, the more damage it can cause.

If the water and/or mould damage was caused by sewage or other contaminated water, then call your landlord or property agent as a professional who has experience cleaning and fixing buildings damaged by contaminated water will be required.

If you have health concerns, consult a health professional before starting cleanup.

Hidden Mould

You may suspect hidden mould if a building smells mouldy, but you cannot see the source, or if you know there has been water damage and residents are reporting health problems. Mould may be hidden in places such as the back side of dry wall, wallpaper, or panelling, the top side of ceiling tiles, the underside of carpets and pads, etc. Other possible locations of hidden mould include areas inside walls around pipes (with leaking or condensing pipes), the surface of walls behind furniture (where condensation forms), inside ductwork, and in roof materials above ceiling tiles (due to roof leaks or insufficient insulation).

Investigating hidden mould problems

Investigating hidden mould problems may be difficult and will require caution when the investigation involves disturbing potential sites of mould growth. For example, removal of wallpaper can lead to a massive release of spores if there is mould growing on the underside of the paper. If you believe that you may have a hidden mould problem, consider hiring an experienced professional.