Overview: When in doubt, don't rip it out

As a nation we appear to love old buildings, and surveys show that we would choose to live in a Victorian house above all others. After the destructive refashioning of the Sixties and Seventies, one might have thought that this affection went hand in hand with an understanding of how pre-20th century buildings function, but not so. Even now, well-meaning owners are imposing the kiss of death on their homes through ignorance.

Marianne Suhr, of the Society for the Protection of Ancient Buildings (SPAB), despairs at the enthusiasm with which we pay out large sums of money for unnecessary treatments against damp and woodworm, to say nothing of our throw-away culture - evidence of which sits in a thousand skips up and down the country. She points the finger of blame mostly at the mortgage lenders. "It's estimated that 95 per cent of rising damp is misdiagnosed. Instead of checking on the state of roofs, drains and the level of the ground, expensive and unnecessary work is undertaken. They also fail to establish whether signs of woodworm and death-watch beetle are historic rather than active, so require all timbers to be sprayed with nasty chemicals. Not only does it kill the spiders - the best predators - but if a house changes hands regularly there is a danger of a build-up of chemicals in the roof space."

Suhr is about to become a familiar face on television, when she and Ptolemy Dean bring their scholarly weight to Restoration, a BBC2 series starting on Friday and fronted by Griff Rhys Jones. In the good cause of highlighting the plight of 30 buildings at risk, it will ask the audience to vote which they would like to be saved.

While all sorts of factors - mostly to do with funds - can bring an ancient building to the verge of collapse, there is a great deal more all those of us who purport to love our period homes could be doing, Marianne Suhr argues. Challenge the builder when he suggests doing away with the lath and plaster ceiling, replacing the complete window just because the sill is rotted or pointing in cement and using modern paints instead of a lime wash.

"It is much easier to have repairs done than people imagine. Why lose a lovely, characterful ceiling that is far nicer than a flat dull replacement, or replace a window with fast-grown softwood that is nothing like as resilient as the original?"

Since it is affluence that has led to the frenzy of makeovers in the past few years, where the mantra of "space and light" has seen interior walls of Victorian houses falling like ninepins, neglect of an old building may in some cases be a saving grace. It is an irony that the society was set up more than 125 years ago to counteract the destructive "restoration" of medieval buildings being practised by many Victorian architects.

In September and October SPAB is running weekend courses on repairing old houses. For information call 020-7377 1644 or visit www.spab.org.uk