Is ignorance bliss?

I still catch myself smiling when I recall a friend’s account of an elderly relative’s visit. It was a rare fine day and during lunch, my friend suggested an afternoon outing. Shopping, a National Trust house or a Country Crafts Centre were all discussed and, eventually, a choice was made.
Lunch over they all got into the car and my friend punched the chosen destination into the satnav. Throughout the journey, his relative listened attentively to the synthetic female voice giving directions. On arrival, the relative, nodding towards the satnav stuck on the windscreen, said “Oh isn’t she amazing – after all we only decided where we were going over the pudding!”
I was listening to a local radio phone-in programme, where listeners asked property related questions and other listeners put forward their solutions. It was interesting that the most frequent questions concerned damp within homes and alarming that many of the replies offered outlandish solutions.
On the basis of that programme, damp and its causes are greatly misunderstood. There are three absolutely fundamental facts that need to be recognised. Firstly, almost all buildings are made of materials that will absorb and release moisture. Next, the warmer air becomes, the more moisture it absorbs and carries; and conversely, when air becomes colder, it can no longer carry as much moisture.
A practical example of these three facts can be seen in a typical living room during winter. The family returns after being out all day and switches on the heating. Soon, the previously cold air warms up and its capacity to absorb moisture increases. It draws moisture from the walls, carpet, curtains, upholstery and from the humid breath of the family. During the evening, the moisture level of the air (humidity) increases due to steam from cooking, laundry, showering or bathing. At the end of the evening, the heating is turned off and the family go to bed. Bedroom windows may, or may not, be opened, but in any event, the family continues to add moisture during sleep by breathing. On average, a person breathes out half a litre of water during a night’s sleep.
As the air in the home cools down, it must reduce the amount of moisture it was carrying. Some will be reabsorbed by fabrics and plaster, but the most rapid off-loading of moisture, will occur at places where the air touches surfaces which are colder than the air itself. The glass of single glazed windows, tiled walls and areas of wall behind furniture are typical locations. Where the contact area is very much colder off-loading will take place faster than the moisture can be absorbed, with the result that, just as in the case of glass or other non-absorbent surfaces, water droplets form. This is condensation and where it occurs regularly, it may result in a fungal mould that typically looks like a haze of black pinhead spots.
What can be done to avoid the problem? Continuous heating is not the answer, because living in the home naturally adds to the moisture hour by hour. Ventilation is the primary cure, but windows cannot be left wide open because whilst it might solve the condensation, you would risk burglary and pneumonia.
The solution lies in compromise. Moderating the peaks and troughs of heating, so that air temperature does not yo-yo too much, will help. Similarly, regular modest ventilation is good, but much of the problem lies in so-called ‘lifestyle’; humidity such as cooking without an externally extracting cooker hood to remove steam before it circulates, and not using an extract fan when showering or bathing. Major culprits are drying washing on radiators or clothes airers, using a steam iron in an unventilated room and gas or bottled gas heaters.
Distinguishing between condensation, damp penetration and rising damp, requires experienced analysis backed up with chemical tests. Too many cases of misdiagnosis have ended up in costly but ineffective treatment. Always seek independent professional advice before spending hard earned money on a ‘cure’ recommended by someone with a commercial interest in doing the work.
©February 2010

NOTE:
The writer is an independent chartered surveyor and has no connection with any firm of estate agents or surveyors. For reasons of client confidentiality he writes under a pseudonym. Comments and enquiries are welcome and may be sent c/o Wealden Advertiser Property, Gardens & Interiors.

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