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Condensation in Properties

We Have a Damp Problem, No it is Just a Condensation Problem By Philip Suter

One the major complaints from a tenant is to contact the Landlord or agent and say they have a damp problem. Quite often they have not opened windows or turned extractors on whilst washing or cooking, they live in a property without a chimney, that has double glazing and now fresh air is getting in. They dry their clothes over a heater in the living room or bedroom and before long there is water running down the glass on the windows, black mould occurring on walls, corners of ceiling and in built in cupboards.

Problems do occur because of problems with a building, however many people just do not make sure the property is properly ventilated.

The following notes provide more information about condensation

Next to shrinkage, condensation is the most common problem in houses. Condensation occurs when warm moist air meets a cold surface. The water in the air then either settles as water droplets on the surface (as it does on windows for example), or, if the surface is absorbent, it soaks into the surface. In the latter case condensation is often not noticed unless or until mould appears.

Mould tends to appear on surfaces where condensation takes place regularly. Because the external walls of a room are usually the coldest they tend to be most affected by condensation (and as a result of mould) particularly at the corners of the room. Mould is often found in cupboards, and behind furniture which is pushed close up against a cold wall, this is because there is poor ventilation in cupboards and behind furniture so that any condensation there gets little chance to dry off.

The moisture can come from cooking, bathing, washing and drying clothes as well as from paraffin heaters and flue-less gas heaters - even breathing produces condensation. However there are ways of controlling condensation. One way is to reduce the amount of moisture in the air (the "humidity"), or another is to increase the warmth of the surface of the walls or other areas affected. Reducing condensation is the best way of controlling mould but it is possible to use fungicidal washes and paints also.


See that your rooms are always warm and properly ventilated. Too much ventilation in rooms can carry away too much heat and this can cause wall surfaces to get so cold it will actually encourage condensation rather than reduce it.

When cooking, keep kitchen door shut and window open.

When bathing, washing or drying clothes, keep the room door shut and the window open. Tumble driers produce a great deal of moist air and this should, ideally, be ducted directly to the outside of the house. If condensation is very bad in the house you should consider drying your clothes at a launderette if you can't dry them outside the house.

If you use a paraffin heater or flue-less gas heater, be sure the window is open a little. Remember that every gallon of paraffin burnt produces 10 pints of water*

(* One gallon of paraffin when burned produces water vapour which turns into water as soon as it touches cold walls and windows. The amount of water is often rather more than the original amount of paraffin, because of existing moisture in the air.)

In cold weather, keep some heating on all the time, i.e. for 24 hours a day. The warmer a house the less condensation will occur - providing that the level of humidity is controlled too.


A house can be made warmer inside by increasing the level of heating or by increasing the insulation. It must be remembered, however, that if there is not heating at all in the house then improving the ventilation won't make it any warmer.

Loft insulation is the most cost-effective way of improving the insulation of a house and a grant may be available from the council towards providing it in certain circumstances and if you are on supplementary benefit, family credit or housing benefit and if the house has less than 3mm of loft insulation.

There are other, more expensive, ways of improving the insulation of a house but loft insulation is the one to start with. The other ways include; cavity wall insulation, double glazing, internal dry lining of walls and external insulated rendering. A relatively cheap way of providing a little extra insulation to a wall is to put expanded polystyrene behind the wallpaper (you can buy this in rolls).


General: - The most important action to take against mould is to try and reduce the condensation in the ways described earlier. In particular if you have mould behind furniture or in cupboards then move them away from the cold outside walls if possible and put ventilation holes in the top and bottom of cupboards if necessary

Cleaning: - Cleaning away mould is best done using an anti-mould solution or wash and there are a number of different brands now on the market. A little while after using them the surface should be scrubbed clean with a stiff brush. These washes kill the mould and it's spores and does provide some short term protection against the re-appearance of mould.

Paints with mould inhibitors: - Longer term protection against the re-appearance of mould can be gained by redecorating the area affected with a mould inhibiting paint. A number of firms produce these.

Several companies produce machines called "dehumidifiers". These machines remove water from the air and produce heat too. They cost about £1 - £2 per week to run. They work best in well heated rooms where the humidity is high. In poorly heated rooms they have little effect. The machine has to have a large capacity (an extraction rate of 2-4 litres per day is needed). Some models are ineffective. In short these machines may be very helpful in some cases, but are not a sure fire cure for condensation.

©jml Property Services

This article was located at the English Cottage Rental website until August 2017

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