THE Listed Property Owners Club claim that many mortgage providers are decreasing the value of period properties.

This is endangering their future by insisting that owners inject a modern damp-proofing system into structural walls. This practice is causing a rapid deterioration of the structural fabric of many historic buildings.

Prior to the use of cement, houses were built with solid walls using a lime mortar, often built directly onto the soil and without the use of a damp proof course. The moisture from below the building rose into the floors and walls and then evaporated into the atmosphere.

The practice of mixing these two different methods by injecting walls with damp-proofing does nothing more than force the moisture into other areas where this breathing process will be inhibited. Owners should forget about trying to keep moisture out.

They should concentrate on allowing the moisture to escape by using lime mortars rather than cement.