Tip Of The Week: Check Out The Damp Patch

Most people buying a new home are told it has rising damp, and are quoted pounds 500 to pounds 3,000 for "damp-proofing" work - all with the approval of their surveyors. But the Building Research Establishment say that true rising damp is rare. Check whether you are being ripped off:

1 Rising damp is characterised by staining at low level on masonry walls, with a distinctively salty "tide mark" about one metre from the floor. If you can't see this then you haven't got rising damp.

2 It only occurs in the absence of an impermeable barrier in the wall known as a damp-proof course. DPCs have been obligatory in British buildings since 1875, so if your home was built after this date, it is unlikely to have it.

3 If there is evidence, it is likely due to raised ground levels, leaking pipes, or plumbing leaks.

4 Damp-proofing companies use electrical moisture meters to "diagnose" rising damp, but these meters only give accurate readings on timber. When used on brickwork, plaster or wallpaper, they give misleadingly high readings.

5 The only way to measure moisture in brick walls is to take a drilled sample and test it in a calcium carbide meter or by weighing and oven- drying. A member of the Association of Building Engineers will be able to provide this test; call 01604 404121.