If we had to name the single most common source of “mystery leaks” on Bristol’s older housing stock, chimney flashing would win comfortably. The chimney punches a hole through your roof, and the lead flashing around it is the only thing keeping that junction watertight. When it fails, water tracks down the stack and shows up as a damp patch that’s often nowhere near the chimney inside.
Why flashing fails
Lead flashing on a Victorian chimney may be decades old. It fails in predictable ways: the mortar holding the flashing into the brickwork joints crumbles and the lead pulls away; the lead itself fatigue-cracks after years of thermal movement; or a previous “repair” with mastic or flashing tape dries out and peels. That last one is depressingly common — sealant over failed lead buys a year or two at most.
How the leak shows up indoors
Water entering at the chimney runs along rafters and surfaces where it likes: a stain on the chimney breast, damp in the corner of an upstairs bedroom, or a drip in the loft a metre or more from the stack. If your damp patch is anywhere near a chimney, the flashing should be the first suspect checked.
The proper fix
A genuine repair means raking out the joint, re-dressing or renewing the lead in the correct code and bay lengths, and repointing it into the brickwork — not smearing sealant along the edge. If the chimney’s mortar and pointing are also tired, doing both at once saves paying for access twice. Details of our approach are on the leadwork page.
What it costs and how long it takes
Most straightforward chimney re-flashing jobs sit in the small-repair bracket — often a single day’s work once access is sorted. Access is the variable: a stack at the ridge of a three-storey Redland villa needs more kit than a squat terrace chimney. As always, get the figure in writing — our cost guide covers what’s reasonable.
Worth checking before winter
Flashing failures accelerate over winter: water gets in, freezes, expands, and opens the gap wider. If you’ve noticed staining near a chimney breast or your flashing visibly lifting, get it looked at in autumn rather than after the January storms. Get in touch for a free assessment — photos included, so you can see exactly what we found.