Its that time of year again

Its that time of year again

No not christmas but the time of year condensation can be present. As usual for the winter months we are being asked to look at damp ceilings, and walls, asking for us to repair the roof. Nine times out of ten it is condensation.


What is condensation?

The air around us contains water vapour produced by the environment and our daily activities, such as cooking and washing. Air that is warm can hold more water vapour than air that is cold. When warm air cools and/or comes into contact with a cold surface it deposits the excess water vapour that it can no longer hold on to the nearest cool surface. The water residue left on the cold surface is called condensation.

In Britain condensation usually happens during cold weather when warm, moist air is generated in one room and then spreads to cooler parts of the building. Condensation is most visible when it forms on non-absorbent surfaces like windows or tiles. However, it can form on any type of surface and may not be noticeable until it causes visible damage, for example black mould. Condensation can lead to misted or streaming windows and, in some circumstances, mould growth and walls that are wet to the touch. It is also one of the most common causes of damp in buildings.

It is extremely important that measures are taken to prevent condensation happening and that any existing damage caused by condensation is treated before the problem worsens.

What are the causes of condensation and how to prevent it?

Too much moisture being produced in the home

As condensation is caused by excess water vapour in the air, minimising activities that produce water vapour will help to reduce condensation.

  • Cover saucepans when you are cooking and do not leave kettles boiling.
  • Avoid using paraffin and portable bottled gas heaters as they produce excess moisture.
  • Dry washing outdoors on a line or put it in the bathroom with the door closed and the window open or the extractor fan on.
  • Avoid drying damp clothes on radiators, as all the moisture they contain will go into the room.
  • When filling the bath add the cold water first, then the hot water. This will reduce steam that leads to condensation by 90 per cent.
  • Wipe over visible condensation on non-absorbent surfaces with a dry cloth to remove the excess moisture.

Not enough ventilation

Ventilating accommodation will help to remove moist air that is being produced.

  • Cross ventilate homes – cross ventilating your home daily will allow drier air from outside to circulate. To cross ventilate, open the windows (they only have to be slightly ajar) at opposite sides of the house or diagonally opposite, if you live in a flat, and open the interior doors.
  • Occupied rooms – rooms that are frequently occupied may need some form of ventilation all the time to allow the moisture produced by breath and water to escape. Keep a small window ajar or a trickle vent open to allow warm moist air to flow out.
  • Kitchens and bathrooms – a lot of excess moisture tends to be generated in these rooms, which means that they will need more ventilation. When you cook, wash up, bathe or dry clothes, open the windows and use an extractor fan if one is fitted. Keep kitchen and bathroom doors shut when these rooms are in use to prevent moisture spreading throughout the building.
  • Bedrooms – if wardrobes are not properly ventilated it can lead to mildew forming on clothes. Try not to overfill your wardrobes, as this will reduce air circulation. Leave space between the back of large furniture and the walls to allow air to circulate and where possible do not put large furniture up against exterior walls.

For safety and security reasons please ensure that you only open your windows while you are in your property and remember to close them when you go out.

Cold surfaces

Condensation typically forms on cold surface. By reducing cold surfaces in your home you can reduce condensation. Loft and cavity wall insulation, alongside draught proofing windows and external doors, will help to reduce the cold surfaces within your home. Please contact Housing Services before fitting any loft or cavity wall insulation.

Please note when fitting draught proofing:

  • Do not block permanent ventilators.
  • Do not draught proof any rooms that have existing condensation problems, as these rooms will benefit from the ventilation.
  • Do not draught proof rooms where there is a fuel-burning heater (gas fire) or cooker.
  • Do not draft proof windows in the bathroom and kitchen.

Temperature of your home

When heating your home try not to have one room at a high temperature while leaving the rest of the property cold. Air in a warmer room will always try to move to a cooler room and this will create condensation. Keeping your entire home at a constant warm temperature when there will help to reduce condensation. Ideally your home should be between 18ºC and 24ºC.

What do I do if I have an existing condensation and/or mould growth problem?

The only long-term prevention for mould growth is to eliminate condensation from your home. If you already have mould growth in your home it will need to be treated. You should not disturb the mould growth by brushing or vacuum cleaning it as this will circulate the spores; increasing the risk of it causing respiratory problems. A Health and Safety Executive approved fungicidal wash should be used to treat the mould growth.

What do I do if I have a problem with damp in my home that is not caused by condensation?

Rising damp

This is a result of moisture from the ground penetrating the lower levels of the building. This type of damp will normally leave a tidemark on the wall. If your property is older it may not have a damp proof course or a damp proof membrane on the solid floors to prevent water seeping through. If your property is damp proofed but you have rising damp, the waterproof layer may be broken.

Soil building up against the outside wall above the damp proof course may also cause rising damp. If the soil is less than six inches below the level of the damp proof course, it will need to be dug away to allow the wall to dry out. Damp internal plaster will need to be replaced, as it will remain damp despite the wall drying out.

Penetrating damp

This is a result of water from the outside of your home leaking into your building. This type of damp is usually a problem in older properties. Penetrating damp can be caused by blocked or faulty rainwater gutters, failed render or rain seeping through a roof where a tile or slate is missing. Repairing faulty rainwater pipes and gutters and replacing render may help to solve the problem.




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