The short answer
By checking the pointing, flashings and pots together and repairing only what has failed. A tall brick stack takes rain on every face, so cracked pointing and worn lead usually explain a damp wall beneath it. Rebuilding comes last, and only when the brick itself has gone. In most cases the stack can be saved, which keeps both the cost and the look of the house intact, and the written quote after the survey says which applies.
Tall brick stacks are among the finest features of a house like Welford Park, and also among its main leak points. A stack stands in the weather on all four sides, and rain finds any gap in the pointing or the lead around it. Wind drives the water sideways into joints that look sound from the ground.
Q3.1What does failed pointing do to a stack?
Pointing means the mortar joints between bricks. Once they wash out, water enters the stack and the brick faces start to flake, frost lifting them in cold snaps. Left alone, a stack can lean as its joints lose strength. Repointing in lime mortar, raking out only the loose joint and matching the finish, usually stops the problem. The brick itself is the part worth keeping wherever possible, because old handmade bricks cannot easily be matched.
Q3.2Why does the lead at a stack let go?
The lead flashing where a stack meets the roof is the commonest source of a ceiling stain beside a chimney. Lead should be dressed into the mortar joints, not simply stuck to the brick with sealant, which fails within a few seasons. At the top, the flaunching, which is the mortar bed that grips the pots, cracks and lets water into the flues. We renew it with a proper fall so water runs off.
Q3.3What do repairs cost and when is consent needed?
The prices below are national typical figures from MyBuilder, updated August 2026, with a lead patch figure from MyJobQuote. Removing a chimney breast always needs Building Regulations approval, and a shared wall brings a party wall notice into play too, so we explain those steps before pricing the work. Our chimney repairs page sets out the options in full.