Property: Rising damp? No such thing

It is one of Britain's best-known building problems. It has inspired numerous gags and given its name to a TV comedy series. But now, it seems, rising damp may not exist at all.

Experts from Lewisham Council in south London are so convinced that rising damp is a myth that they are offering a cash reward to anyone who can prove them wrong.

Mike Parrett, manager of Lewisham's housing disrepair team, said several hundred cases of rising damp were diagnosed in the council's housing stock each year, costing his department millions of pounds in damp-proofing work.

But in most cases the treatment failed because, Mr Parrett explained, the so-called "rising damp" turned out to be condensation caused by poor heating and ventilation, or penetrating damp from raised ground levels or leaking pipes.

The council has offered a pounds 50 reward to find a genuine case of rising damp, with no success. "Now we are considering raising the reward to pounds 500," he said.

Mr Parrett, who last month received an Institute of Maintenance and Building Manage- ment award for his work on damp, said rising damp verdicts usually resulted from the misuse of electrical moisture meters, which are accurate for timber but give falsely high readings on brick walls.

His team uses more accurate calcium carbide meters to check moisture levels in walls, and tests for the presence of ground salts. He said they had yet to find a genuine case of moisture being drawn up from the foundations.

Launching the reward scheme last week, Mr Parrett said: "There are hundreds of damp-proofing firms, all using the same methods. When you get one in for a survey it's hardly surprising if they say you've got rising damp - it's how they make their living.

"The point of the reward is to convince our tenants that rising damp is a myth. Ideally we'd like to remove 'rising damp' from the building vocabulary in Lewisham, so that our repair money can be spent on real solutions to real problems. Every wrong diagnosis of rising damp is costing us pounds 5,000, which could provide central heating and ventilation for two properties; improvements that we know really will cure dampness."

Lewisham Council's stand seems certain to provoke a debate within the building industry about chemical damp-proofing, which is thought to cost local authorities and owner-occupiers between pounds 100m and pounds 200m every year.