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Is it Damp, or is it Condensation?

When we think of properties we hear so much about “Location, Location, Location” however when you find that desired property and you are living in it, it’s important to consider some of the practicalities of living in your home and in particular “Ventilation, Ventilation, Ventilation”!

It has been determined that the last 12 month period has been the worst nationwide for occupants reporting “damp” in their properties.  In the majority of cases it has turned out that the property is suffering from lifestyle-induced condensation caused by lack of ventilation in the property.  A local damp company has decided to charge a nominal amount for attending properties where reports of “damp” are found to be not as a result of a structural problem with the property or damp ingress, but merely because of condensation caused because of lack of ventilation.

What is Condensation?

At this time of year, when condensation appears on the window panes of the property it is a clear indication that there is excessive moisture in the atmosphere.  This can be caused by a number of different factors (cooking, washing, drying clothes etc) but is remedied by ventilating the property.  Even though the weather may be cold outside and occupants will not want to leave a window open, or they may be concerned about security (if on the ground floor), ensuring that the property has a good balance between heating and ventilation, will ensure that moisture levels are kept to a minimum.

Condensation will appear on cold surfaces (such as window panes and tiles) as moisture and water droplets.  It can appear on walls and carpets as mildew (black speckled substance).  Whenever condensation or mildew appears, steps should be taken to wipe off the moisture or clean off the mildew.  There are some very good commercial “mould and mildew cleaners” on the market, though a diluted bleach solution should provide the same results.

Ventilation is only effective if consistent throughout the whole of the property as condensation is encouraged by poor air circulation, where stagnant air pockets form (if furniture has been stored or wedged up against a wall) and the first evidence is the appearance of water droplets and/or mould mildew.

Where does it come from?

Generally, condensation in houses is mainly a winter problem particularly where warm moist air generates in living areas and then penetrates to the colder parts of the building – ie, the windows.  The moisture in the air comes from a number of sources within the house and water vapour is produced in relatively large quantities from normal day to day activities.  For example, it is suggested that a 5 person household creates approx 10 litres of water vapour into the air every day and this is without taking into account vapour produced when heating is activated.  Building Research Establishment Digest 297 suggests that typically, moisture producing activities with levels of moisture produced are:-

  • Breathing (when asleep) – 0.3 litres

  • Breathing (when awake) – 0.85 litres

  • Cooking – 3 litres

  • Personal washing – 1 litres

  • Washing and Drying clothes – 5.5 litres

What can be done to prevent it? 

Theoretically it is possible to avoid condensation by adequate ventilation.  The suggestions would be:-

  • NEVER dry clothes inside the property.  Nor should damp articles be placed directly onto the radiator.  All drying appliances should vent externally, in addition to ensuring that a window is open.

  • Regulate the heating, so that there is no time when the fabric of the building is allowed to cool down, by keeping heating on low temperature during the day.  If the building temperature is constantly regulated, this will eliminate the typical “moisture producing activities” (usually concentrated into morning and evening).  Trying to heat a whole house up quickly, say in the evening may cost you more too.

  • After a bath or shower, ventilate the room to the outside, not to the rest of the house - just opening a window and closing the door to the room will help.  The window should be left open after you have finished bathing or showering.   If you have an extractor fan, this should be switched on whilst bathing / showering and left on after you have finished so that excess moisture is removed.  Water spillages should be removed and not left to evaporate.  Puddles of water will not disappear of their own accord and have to go somewhere.

  • When cooking, keep kitchen doors closed and open windows – use an extractor fan if you have one.

  • Don’t fill cupboards and wardrobes too full – allow air to circulate.

  • Avoid stacking boxes or storing clothes in rooms particularly against outside walls – condensation (mould/mildew) may form behind them – allow air to circulate.

  • Keep a small window open or open a vent in the window if you have one.  Nobody likes a draughty space, but some ventilation is essential.

You should remove condensation from windows/surfaces as it occurs.

You should clean off any mildew/mould which has been formed by the condensation – this can be by using a commercial “mould & mildew cleaner” or a diluted bleach solution – using the relevant precautions.

Of course, it is important to establish that not all forms of dampness are caused by lifestyle-induced condensation.  Damp can also come from leaking pipes, rain penetrating through and rising damp.  These forms of dampness often leave a tidemark so it is important to establish if these may be the cause of the problems experienced.


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