Damp proofing in Yarm

A High Street built before damp proof courses existed

Yarm's High Street is Georgian, and the buildings behind those frontages were constructed with soft brick, lime mortar and no damp proof course whatsoever. They were designed to take up moisture and release it again through walls, floors and lime plaster. Modern impermeable finishes break that cycle, and a surprising amount of damp in old Yarm property is caused by well-intentioned twentieth century improvement rather than by any original defect.

The river

The Tees loops around the town, and low-lying property near it has both a high water table and a flooding history. Cellars in that band are wet by nature. Where they need to be dry, a drained membrane system with a sump and twin pumps is the appropriate approach, sized for the water actually arriving rather than for a hopeful minimum.

Listed buildings and consent

Numerous High Street buildings are listed. Injecting a chemical damp proof course, replacing lime plaster with gypsum, or repointing in cement can all be inappropriate and, on a listed structure, may need consent from Stockton-on-Tees Borough Council. A surveyor who raises that at the outset saves a great deal of trouble later.

The newer parts of Yarm

The larger detached and executive housing off Green Lane, Leven Bank and the more recent developments is standard cavity construction, generally well insulated and fairly airtight. Its typical fault is the opposite of the old town's: not enough ventilation, so moisture from showers, cooking and drying washing settles as condensation and mould in the coolest bedroom corners.

Prices in Yarm

Damp and timber surveys £250 to £450 on a larger or listed property. Lime plastering £60 to £110 per square metre. Lime repointing £55 to £100 per square metre. Cellar membrane systems from around £6,000 for a habitable conversion. PIV ventilation £600 to £1,200.