Chimney repairs and leadwork in Hythe, Folkestone and Kent

When water shows up on a chimney breast, or on a ceiling next to one, it is almost always getting in at one of five places. The fix depends entirely on which, so we find out before we quote: resealing a flashing will not stop a leak that is coming through the flaunching.

Chimney mortar has a harder life than any other mortar on a house. The weather gets at every face, and on a stack that served coal fires, the flue gases leave sulphates in the mortar that make it swell over the years. It usually swells more on the wetter side, which is why so many old stacks lean slightly away from the prevailing weather.

A slight, long standing lean on an old stack is common. What matters is change: a lean that is getting worse, bricks loose at the top, or pots that have shifted. Repointing is the answer while the brickwork is sound. Where the top courses are loose or the lean is growing, the stack comes down to sound brickwork and is rebuilt, reusing the old bricks where they are good enough, with new flaunching on top.

Chimney work almost always needs a scaffold round the stack, and on a terrace the stack is often shared with the house next door. We will tell you at quote stage whose chimney is whose and what that means, because it is far easier to agree before the scaffold goes up.

Lead is still the best material for weathering the joints on a roof, because it can be dressed to any shape and lasts a very long time when it is fitted properly. Most of the lead failures we are called to are fitting faults rather than worn out lead: lengths that are too long, lead fixed so it cannot move, or flashings stuck on with sealant instead of tucked into the brickwork.

Done right, lead goes on in short lengths so it can expand and contract with the weather, tucked into a raked out mortar joint, wedged and pointed. The thickness is matched to the job, with heavier lead in gutters and valleys than in a simple flashing. On a chimney that usually means a front apron, stepped flashings down each side with soakers under the tiles, and a back gutter behind.

Where two roof slopes meet in a valley, or a roof drains into a gutter behind a parapet wall, the lead is doing all the work, and there is nothing behind it if it fails. Old lead valleys split along their length, and box gutters behind parapets fill with silt, leaves and gull nesting material until the water overtops the lining and runs into the house.

On terraces a valley or box gutter is often shared with the houses either side. Relining one means laying the joints between sheets so water runs over them rather than into them, and outlets big enough to cope with a storm off the Channel.

An unused flue with an open pot takes rain straight down into the house and lets heat straight out. The answer is a cap, but it has to be a ventilated one. A flue sealed at both ends traps moisture and gives you damp patches on the chimney breast instead, so the fireplace or flue below needs a vent too, to keep air moving through it.

If you might want a fire again one day, say so, because a cap that suits a disused flue is not one to light a fire under.

Lead is valuable and it does get stolen, from houses as well as churches. If yours has gone, the roof is open to the weather and needs a temporary cover straight away, then proper replacement. Report the theft to the police and to your insurer.

Where the risk is high, or on a low extension where the lead is easy to reach, there are lead free alternatives that look similar and have no scrap value. They are not a like for like substitute everywhere, and on a listed building the conservation officer is likely to expect lead, so it is a decision for each job rather than a rule.