Condensation in your property

A guide to the causes and how to remedy the problem

CONDENSATION in your home… is your home damp?

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What is dampness?

Dampness can originate from:

  • Leaking pipes, wastes, drainage and overflows;PCA_Condensation_leaflet_2013-page 1
  • Rain water from defective roof coverings, blocked or leaking gutters and broken pipes;
  • Penetrating dampness around windows, through walls and due to raised ground levels;
  • Rising damp due to lack of, or no effective, damp proof course.

Condensation dampness’ is a condition that affects many homes and has probably become the major cause of ‘environmental’ dampness within a property. Condensation is particularly common in homes which are poorly heated and poorly insulated and usually gets worse in the colder winter months i.e. ’the condensation season’.

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 also notice it when you see your breath on a cold day, or when the mirror mists over when you have a bath. Kitchens and bathrooms are often primary sources of atmospheric water. Moisture is released into the air through normal daily activities such as washing, cooking, drying clothes, showering and bathing. This can occur commonly on windows or external walls, or cold surfaces within the fabric of the property. Look for it in corners, on or near windows, in or behind wardrobes and cupboards. It often forms on north-facing walls.

The problems of condensation can lead to staining and mould growth, damaging wallpaper, wall surfaces, window frames, furniture and clothing. The development of mould growth is the most tell-tale sign that is frequently associated with condensation. The appearance of mould may be black, white, yellow or green in colour, depending on the specific type of mould and the surface which it grows on. Black spot mould (Aspergillus niger or Cladosporium spp), for example forms pyramid profiles in wall corners and at wall/floor or wall/ceiling margins as a consequence of condensation.

Moulds are hydrophilic fungi in that they require high levels of surface moisture. Capillary held dampness (such as that originating through rising dampness) is not sufficient to cause mould growth. The mould requires free moisture on the surfaces to germinate.

Tiny spores produced by the mould and the higher numbers of dust mites due to the moist conditions can increase the risk of asthma and respiratory illnesses in some people.

Maintaining a reasonable balance between heating, ventilation and insulation can reduce excessive condensation however, a major review of lifestyle and occupation of the property is often necessary.

In the short-term you should wipe off the condensed water from windows and sills every morning during the condensation season. Wring out the cloth into a sink rather than drying out on a radiator.

Mould Cleaning

Regular cleaning away of mould is vital. To remove mould, wipe down walls and window frames with a preparatory mouldicide or fungicidal wash which carries a Health and Safety Executive approval number. Follow the manufacturer’s instructions precisely which will provide longer term prevention. Spray containers of mouldicide can be obtained from chemists and retailers. Mould kits can be obtained from specialist suppliers.

Dry clean mildewed clothes and shampoo carpets. Disturbing the mould by brushing or vacuum cleaning can increase the risk of distribution of spores and respiratory problems.

After treatment, redecorate using a good quality fungicidal paint to help prevent mould. Note: this paint is not effective if overcoated with ordinary paints, emulsion or wallpaper. You can also obtain a mouldicide solution additive to mix with the paint. When wallpapering, use a paste containing a fungicide to prevent further mould growth.

Using a dehumidifier can control the airborne moisture and help reduce this problem, however dehumidifiers will not solve the cause(s) of the condensation problem.
The only lasting way of avoiding severe mould is to eliminate the cause of the dampness – condensation.

How to avoid condensation

Produce less moisture
Reduce the potential for condensation by producing less water.

  • 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
  • When filling the bath, run the cold water first then add the hot – it will reduce the steam which leads to condensation by up to 90%
  • Never dry laundry on radiators
  • Dry washing outdoors if possible, or put it in the bathroom with the door closed and the window open or extractor fan on
  • Extractor Fans should be automatically humidistat controlled – not solely activated by a light switch
  • If you use a tumble dryer, make sure it is vented to the outside (DIY kits are available for this) or that the tumble dryer is of the new condensing type
  • Don’t use your gas cooker to heat your kitchen as it produces moisture when burning gas (you will notice the windows misting up)
  • Never use bottled gas heaters (Calor etc.) as they produce about 8 pints of moisture from an average-sized gas bottle

Ventilate to remove moisture
You can ventilate your home without making draughts.

Some ventilation is needed to get rid of the moisture being produced at the time, including that from people’s breathing. Keep trickle vents open at all times, alternatively open small window/top lights.

  • Use passive Vapour Vents if no trickle vents are fitted to windows
  • Do not have airbricks fitted at low levels
  • Kitchen and bathrooms require more ventilation due to cooking, washing, bathing and drying creating high levels of moisture which means opening windows
  • Ideally these rooms should be fitted with humidistat controlled extractor fans (these work automatically when humid air is detected
  • Close the bathroom and kitchen doors when these rooms are in use, even if the kitchen or bathroom has extractor fans (this stops the moisture reaching other rooms, especially bedrooms which are often colder and more vulnerable for condensation)
  • Allow space for the air to circulate in and around your furniture
  • Open doors to ventilate cupboards and wardrobes
  • Leave space between the backs of wardrobes and the wall
  • Where possible, position wardrobes and furniture against internal walls i.e. walls which have a room on both sides rather than external walls
  • To reduce the risk of mildew on clothes and other stored items, allow air to circulate round them by removing ‘false’ wardrobe backs or drilling breather holes in them
  • You can place furniture on blocks to allow air to circulate beneath
  • Never overfill wardrobes and cupboards as it restricts air circulation

The use of Positive Pressure FLAT or LOFT ventilation systems can be considered, whereby fresh, dry filtered air at ambient temperature is introduced continuously into the property – diluting and displacing stale, moist air and reducing the cause of condensation within the property.

How to avoid condensation

Heat your home a little more
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 homes where the bedrooms are not above a warm living room.

If you have central heating, set it to provide background warmth in ALL rooms including unused rooms. Otherwise install suitable thermostatically controlled heaters where necessary.

The thermostats will help control heating and costs, remember to provide background ventilation at the same time. Use the heating system on a regular balanced cycle with all radiators working to all rooms during colder periods.

DO NOT USE PARAFFIN OR BOTTLED GAS HEATERS FOR THIS PURPOSE.

Insulate and draft proof
Draughtproofing of windows and outside doors will help keep your home warm which should result in lower fuel bills. When the home is warmer, condensation is less likely to occur.

When draftproofing:

  • Do not block permanent ventilators
  • Do not block unused chimney breasts – fit a ventilator/air brick
  • Do not draughtproof rooms where there is a fuel burning heater (e.g. Gas Fire)
  • Do not draughtproof windows in bathrooms and kitchens

Insulation should also be considered for:

  • Roofs
  • Cavity walls
  • Sloping ceilings (soffit)

If you have sloping ceilings, under roof slopes, these are traditionally poorly insulated. Sloping soffits can be insulated internally with dry-lining or insulated plasterboard – otherwise the roof requires stripping back to fit insulation between the rafters.