Damp Damp often appears as discolouration on the chimney-breast, most often in bedrooms but also in loft/ attic/ roof spaces and sometimes above the fireplace.
The causes are usually: Closed appliances: Modern efficient heating appliances such as stoves and boilers put the heat where it is required so it is not wasted up the chimney. Flue gases leaving the appliance are therefore cooler and in an un-insulated chimney the temperature may drop below dew-point, condensing into a liquid. Un-vented flues: Most masonry is porous and un-vented flues will trap moisture, which may then appear on the chimneybreast as damp. Faulty flashings: If the flashings protecting the outside of the chimney are faulty, water will get in and may produce damp patches on the walls and ceilings. These are normally seen to be worse after heavy rainfall. Weathered Masonry: Rain will penetrate open textured masonry, faulty flaunchings, and cappings. It will run down inside the chimney to a ledge (or other obstruction) where it will cause a damp patch. This can occur at any point on the chimneybreast. In all these cases, the solution is to consult your chimney specialist, builder or roofing contractor.

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