Open your windows and cast out the evil spirits

Doctor On The House Worried by damp? The solution is obvious, says Jeff Howell. Learn how your home works and avoid the hocus-pocus

The British like to affect a casual indifference to the buildings in which they live, work and are entertained. This attitude lets them abdicate responsibility for the buildings' care and delegate it to a small group known as "builders".

Take the common problem of condensation. If people cared for their homes they would make sure that the water vapour produced by cooking, showering or washing clothes was directed to the outside of the building rather than allowed to circulate inside, looking for suitable cold surfaces to condense on.

Every building is equipped with a simple mechanism for achieving this, called opening the windows. When the "wet" rooms - kitchen, bathroom and utility room - are being used, the windows should be open and the internal doors to the rest of the house should be closed. But many people will not do this; they prefer to keep the bathroom and kitchen windows closed and, if the rooms get a bit steamy, will even open the internal doors to disperse the fog.

The result is that water vapour finds its way into rooms and cupboards far from the source and condenses out on cooler surfaces. This usually sets off black mould growth on walls and ceilings and green mildew on shoes and fabrics. Leather jackets and handbags in built-in bedroom wardrobes are prime victims.

The damage is often viewed as some kind of mysterious fault of the building - that is, the house suffers from "damp" which can only be cured by the divine ministrations of a "specialist". As we approach the millennium, the prevalence of these medieval attitudes is worrying. You don't think so? For "damp" try saying "evil spirits" and for "specialist" read "exorcist". Our late 20th-century culture is full of witchcraft, and nowhere is it more prevalent than in the construction industry.

Why should this be? It doesn't help, of course, that in our Western culture technology is considered inferior to the arts, to the extent that people who would be ashamed to admit to poor reading and writing skills actually like to boast about their innumeracy: "Oh, I'm useless with figures, ha ha." Lack of knowledge about films or paintings can be held up as a sign of ignorance, but an inability to fix a dripping tap or change a fuse is hailed as an endearing eccentricity - proof that the owner's mind is on "higher" things.

And yet, buildings are important in people's lives - we all spend most of our time in them. When on holiday we visit them - museums, churches, castles. Past civilisations are defined by the remains of their buildings; in some cases, such as Stonehenge or the Peruvian pyramids, these may be all that remains.

Most importantly of all, buying a home remains the major financial transaction in most people's lives. And still the population at large remains fundamentally ignorant about how buildings are put together. Hang on, did I just say the population at large? For God's sake, half the people who describe themselves as property professionals don't know how buildings are put together. I mean estate agents, of course, but also many surveyors and some architects.

The building industry, like nature, abhors a vacuum. If there is a wide gap in the public's knowledge, then this creates a market opportunity, and someone will always be crafty enough to come along and exploit it. You should make it your business to find out how your home works, because if you don't, someone else will surely turn up to fill the gap in your knowledge - very often with a bit of hocus-pocus.