Lead flashing rarely gets much thought until it fails, but the strip of lead running around the base of a chimney is doing one of the hardest jobs on the whole roof — sealing a permanent junction between two different materials that expand, contract and move at different rates through the seasons. In our experience, more chimney leaks in Lawrence Weston trace back to failed leadwork than to the brickwork itself, which is why it deserves attention in its own right rather than being treated as an afterthought to repointing.
The flashing typically works alongside soakers, small individual pieces of lead tucked under each course of roof tiles or slates against the chimney, and a back gutter behind the stack that channels water safely around it rather than letting it pool. Any one of these failing on its own is enough to let water in, even if the rest of the setup looks sound, which is why a leaking chimney needs the whole junction checked rather than just a glance at the visible flashing strip.
Common causes of failure include the lead simply ageing and cracking after many years of thermal movement, mortar pointing that has come loose from the chase cut into the brickwork where the flashing is tucked in, or the flashing being lifted or torn in a storm. On older properties in Lawrence Weston, lead that was undersized or poorly detailed when originally fitted can also fail well before its time, regardless of how sound the rest of the roof is. Poor-quality repair work carried out at some point in the past — flashing bedded in silicone sealant rather than properly dressed and pointed, for example — is another surprisingly common cause of premature failure that only becomes apparent once the sealant itself perishes.
The fix depends on what has actually gone wrong. Sometimes it is a case of re-dressing and re-fixing existing lead that has simply worked loose, repointing the chase to secure it properly. In other cases, particularly where the lead has cracked, split or corroded, full replacement with new code lead is the more sensible long-term option rather than patching something that is already at the end of its life.
Because leadwork problems are notorious for showing up as a stain or damp patch some distance from where the actual fault is, tracing the real source properly is important before any repair is carried out — patching the obvious spot without finding the true entry point often means the leak simply reappears after the next heavy rain. A proper trace usually means getting up to roof level and checking the whole junction methodically, rather than assessing it from a ladder or from the ground and hoping the fault is where it looks like it should be.
If you have noticed a leak around a chimney breast or in a loft space in Lawrence Weston, it is worth having the leadwork properly inspected rather than guessing at the cause. Brunel Roofing Bristol carries out leadwork repairs and replacements with a free assessment beforehand and a 15-year guarantee on completed work, plus a 24-hour emergency call-out if water is actively coming in.
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