Chimneys
The most exposed brickwork on the building
A chimney stands above everything else, gets weather from every side, and on most London houses has not been touched since it was built. It is the source of a large share of upstairs damp.
What goes wrong, and what it looks like inside
- Failed pointing
- Open mortar joints let water into the stack, which then travels down the flue and appears as a brown-edged damp patch on a chimney breast, often in a bedroom.
- Cracked flaunching
- The mortar fillet holding the pots. Once it cracks, water runs straight into the top of the stack. One of the cheapest repairs and one of the most commonly overlooked.
- Redundant flues
- A disused flue with no cap takes rain directly. Capping while leaving the flue ventilated stops the water without trapping moisture in the stack.
- Failed flashings
- Front apron, side steps and back gutter. A missing back gutter behind a stack on a pitched roof is a classic and persistent leak.
- Spalling brickwork
- Frost damage blowing the faces off bricks. Where it is extensive the stack needs rebuilding rather than repointing.
- Leaning stacks
- Usually sulphate attack from an unlined flue, expanding the mortar on one side. A leaning stack is a structural matter and is looked at as one.
Repointing, rebuilding and removing
Repointing is raking out the old mortar and replacing it. On a period property the mix matters: a hard cement mortar on soft old brick pushes the damage into the brick faces instead of the joint, which is why so much 1970s repointing has left spalled brickwork behind it.
A rebuild takes the stack down to a sound course and builds it back up, reusing the original bricks where they are good. It is the answer where the brickwork itself has gone, or where the stack is leaning.
Removing a stack entirely is an option where the flues are genuinely redundant — but it needs the roof making good properly, and it needs care where the stack is shared with a neighbour or is part of the character of a terrace. It is also work that a conservation area may have a view about.
Chimney work we have carried out
Case studies are published here as jobs finish, with photographs taken on site before, during and after the work.
Chimney questions
My chimney breast is damp but the roof is fine. Why?
Because the water is coming down the stack rather than through the roof covering. Open pointing, cracked flaunching or an uncapped flue all deliver water into the brickwork above the roofline, and it shows up in the room below. It is a chimney repair, not a roof repair.
Should I cap a chimney I no longer use?
Generally yes, with a vented cap. Sealing a flue completely traps moisture inside it and can make the damp worse rather than better. A cowl or vented cap keeps the rain out and lets the flue breathe.
Can chimney work be done without scaffolding?
Minor work at low level, sometimes. Repointing or rebuilding a stack needs a proper working platform around it — that is a scaffold with a chimney lift, and it is a meaningful part of the cost. Anyone offering to repoint a stack off a ladder is telling you something about how the work will be done.
Not sure what your roof needs?
An inspection ends with a written report and photographs, whether or not you go ahead with the work.
Inspection fee: £99.00.