Condensation, how it occurs, potential problems and how to resolve it.
Condensation occurs when warm moist air comes in contact with cold surfaces such as walls and windows. On windows, it’s quite apparent as windows are usually colder than walls. However, condensation does occur on walls if the property is not ventilated correctly. This constant dampness can cause the plaster to delaminate off the walls and lead to Wet and Dry Rot.
I often find that in October and November, I may get a call off tenants saying that all of a sudden they have symptoms of condensation, which they simply refer to as damp. It can happen when the weather changes and there is heavy rain.
The best I can describe it as follows: I’m sure that at one time you have been in the car with perhaps more than 2 people, in the evening and it starts to rain. The next thing that happens is the windows ‘steam up’. So you turn the ‘air vents’ on and put the air conditioning on. Well, what has happened? Nothing inside the car has apparently changed to cause the windows to steam up, it’s the fact that the rain outside the car has cooled the windows to the point where the warm moist air, changes form a ‘gas’ to a ‘liquid’, I’m sure we all remember that from our physics lessons in school.
Well, it’s exactly the same in a house. A stone box, filled with moist air from everyday activities, boiling kettles, boiling potatoes and pasta on the hob, running hot baths and showers, and worst of all placing your smalls on the radiators to dry. If you don’t ventilate and heat, this moisture will ‘condensate’ on the windows and walls.
Evidence of Condensation Problems
Evidence of condensation can be Black spots and patches in corners of rooms and behind furniture, particularly wardrobes and green mould on leather and wood.
Where properties have been left unattended and high levels of moisture have occurred due to water penetration, you may have to employ various methods to dry the property out, for example, hiring a dehumidifier. Condensation is the easiest defect to resolve, as the built-up moisture will be vastly reduced once you have tackled the issues and commenced drying the property out.
Resolving Problems
I recall some years ago when working in the Architects department for a Local Authority in the ’80s, I managed one particular refurbishment scheme of over 40 houses where the work included the replacement of timber windows with uPVC units and the cavity walls were injected with blown mineral wool.
After a few weeks the council tenants were complaining en mass that they were experiencing ‘damp’ problems in the houses and blamed it on the cavity insulation, when in fact what was happening, was whereas previously the moisture generated from their activities such as boiling kettles and hanging clothes to dry on the radiators etc was being extracted through ‘natural’ ventilation from the ill-fitting timber windows. Now they had new windows with seals the houses were not being ventilated and black spots began to appear in the corners of the rooms and their clothes started to go mouldy. So instructions were issued to open windows, use the trickle vents or use the night latch to maintain constant ventilation and to keep the heating on a low setting.
This resolved the problem.
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Thanks for reading.
Mike Woods, MCIAT
