Poulton Remedial Services - Hygroscopic

One source of dampness which is often misdiagnosed is hygroscopic dampness on chimney breasts.

Defective flashings and other potential sources of rainwater ingress are blamed but often not the cause.

We frequently see chimneys that have been removed to below the roof line and tiled over, still show signs of dampness many years later.

This is caused by condensation in the flue causing salts, which are a residue from the combustion of fossil fuels to become soluble and migrate to the surface where they are seen as damp patches and sooty stains.

Ventilating the flue is important but ultimately re plastering using salt resisting plaster or lining with air gap membrane systems will be required to cure the problem