Chimney repairs & leadwork in Macclesfield

The chimney is the wettest, coldest, most exposed masonry on the house — it takes weather from every side and has nothing above it — so it is the first thing to fail and the single commonest source of a roof leak. On a Victorian terrace, the stack is usually where to look first and the covering last.

Three things go, in a fairly reliable order. The flaunching — the mortar fillet holding the pots — cracks and lets water down the inside of the stack. The pointing erodes, so the brickwork itself starts drawing water. And the lead flashing at the roof line either lifts out of its chase or was never properly wedged and pointed in the first place. That last one is the one people paint over with black bituminous goo, which hides it for a season and then traps the water behind it.

Leadwork is a craft with actual rules, and most of the failed lead on Macclesfield roofs failed because they were ignored. Lead moves a lot with temperature, so pieces have to be kept short — code 4 flashings in lengths of about 1.5 metres, lapped, never run as one continuous strip. A single long piece looks tidier on the day and splits within a few years. Mortar fillets instead of a proper stepped flashing are the other giveaway.

Two things to know before work starts on a terrace. A stack sitting on a party wall is very often shared, which brings the Party Wall etc. Act 1996 into it and means the neighbour has to be served notice. And if you have had the fire taken out, an unused stack still needs to be ventilated top and bottom, or it will sweat and stain the chimney breast from the inside — which people then report, understandably, as a roof leak.