Before You Decide on a Chimney Repair

A damp patch near a chimney is a symptom, not a diagnosis. Water can be entering through the leadwork at the roof junction, through open mortar joints in the stack, through a brick that has lost its face, through cracked flaunching at the top, or through a slipped slate a course or two below. It can also be condensation in a redundant flue that has been sealed without ventilation.

Before agreeing to any scope of work, ask what the cause has been identified as, and what the reasoning is. A contractor who has looked properly will be able to tell you. Our leaking chimney page goes through the possibilities one at a time.

Visible deterioration does not automatically mean the stack has to come down. Weathered joints on a stack with sound bricks is a repointing job. A handful of failed bricks is a cutting out and replacing job. Rebuilding becomes the better use of money when mortar loss runs deep, bricks have broken up across several courses, or there are signs the stack has moved.

If you are quoted for a full rebuild, it is reasonable to ask what rules out a repair. Equally, if you are quoted for pointing on a stack with crumbling bricks, ask how long that is expected to last.

Two quotes for the same chimney can differ mainly in what they leave out. Check whether the price covers:

• Scaffolding or other access, and how long it stays up
• Replacement bricks, and what happens if more are found to be damaged
• The area of repointing, and whether it is all faces or just the worst one
• Leadwork, and whether it is being repaired or renewed
• Flaunching, pots and any cowl
• Debris removal from the roof, gutters and garden
• Making good to slates, plaster or decoration

This matters most on older property, and a lot of Carlisle housing qualifies. Victorian brickwork was generally bedded in a softer lime based mortar that allowed slight movement and let moisture escape. Repointing that stack in a dense cement mortar can trap water in the brick, pushing the damage into the brick faces. On a modern stack, a standard sand and cement mix is usually the right answer.

Ask what mix is proposed and why. Ask what bricks will be used for any replacement, and whether they are matched or reclaimed. On a period terrace, a mismatched brick or a hard grey cement joint is visible from the street for the next fifty years.

Access often shapes the price more than the masonry does. Terraces with no rear vehicle access, shared yards, narrow lanes, tall stacks on steep slate roofs, conservatories and neighbouring gardens all affect how a scaffold can be put up. It is worth walking the route with whoever is quoting, and confirming whether neighbouring permission is needed. If a quote seems noticeably cheaper than others, check what access it assumes.

On many terraced and semi detached houses in Carlisle, a single stack sits on the party wall and serves both properties. If the shared part needs work, the sensible approach is to speak to the neighbour early rather than after the scaffold arrives. Repairing half a shared stack rarely gives a good result, and where removal or reduction is being considered, party wall procedures may apply.

Chimney stacks contribute a great deal to the character of older streets, so alterations to them can be controlled. If your property is listed or sits within a conservation area, check what is required before altering the height, appearance or materials of a stack. We are not able to give planning or legal advice. Cumberland Council is the right place to confirm what applies to your address. This is particularly relevant if you are considering removal or reduction.

Clear photographs help enormously at the enquiry stage. Take them from the ground with the zoom on your phone, or from an upstairs window if you have a safe view of the stack. Include the whole chimney, the point where it meets the roof, and any damp patch inside. Please do not go up on a roof, out of a window or up a ladder to get a better angle. If the photographs are not enough, someone can come and look.