Chimney repairs in Bury St Edmunds, Ely and Thetford

How chimney repairs works

The chimney is the most exposed masonry on the house. It has weather on four sides, nothing sheltering it, and a flue running up the middle that carries moisture. That is why stacks need attention decades before the walls below them do.

Getting the mortar mix right matters more on a chimney than anywhere else. A hard modern cement mix on soft old brick traps water in the brick and the face spalls off in the first hard frost. On period property the pointing wants to be softer than the brick, so it is the mortar that weathers and not the wall.

If a flue is not in use it still needs to breathe. Capping a stack completely, with no ventilation, is a common cause of damp on a chimney breast, because the moisture in the brickwork has nowhere to go. A vented cap costs almost nothing and prevents it.

Flaunching is the mortar weathering on the top of the stack that holds the pots in and sheds water off it. It is the first thing to crack, it is cheap to renew while somebody is already up there, and once it has gone the water runs straight into the top of the brickwork and works down. It is worth doing at the same time as anything else on the stack.

If a stack has been rendered or painted at some point, be careful. A cement render on an old brick chimney traps moisture in the brick, and when it starts to blow it comes off in sheets and takes the face of the brick with it. Sometimes the right answer is taking the render off rather than patching it, and we will say so.

What the job includes

• Raking out and repointing the stack in a mortar mix suited to the brick
• Rebuild from the roof line up where the brickwork has gone too far
• New flaunching, the mortar weathering that holds the pots
• Pots, cowls and terminals replaced or capped where a flue is unused
• New lead soakers, stepped flashing and back gutter around the stack
• Scaffold or tower access, priced openly on the quote

Signs you need it looking at

• Mortar joints raked out by weather so you can see the shape of every brick
• Cracked or missing flaunching around the base of the pots
• A pot leaning, or a cowl that has moved
• Damp on the chimney breast in a bedroom or in the loft
• White salt staining on the brickwork inside