Chimneys and flues are subjected to intense heating and cooling cycles, condensation and aggressive chemical reactions caused by hot flue gases. Above the roof line they take the full force of the weather.
Common chimney problems
Leaning chimneys — a combination of erosion, acid attack and salt crystallisation can cause a chimney to lean. The BRE Good Repair Guide says any chimney that leans more than 1mm in 100mm is unsafe. Where the shaft wall is half a brick thick, a lean of 35mm could be tolerated, but no more.
Vertical cracks — thermal expansion of the flue lining can cause vertical cracks in the structure of the chimney, particularly where the flue is hidden within the thickness of a wall.
What we do
Repointing in matched mortar, replacement of flaunching at the head, new lead flashing to the roof junction, replacement of broken or weathered bricks, full or partial rebuild where the structure has moved past safe tolerance. All work follows BRE good-repair guidance.