Flashing is the weatherproof joint around the chimney
The first thing to establish with chimney flashing problems is the pattern. This guide is specifically about defects in the lead or other weathering where a chimney meets the roof. For chimney flashing problems, details such as timing, location and recent changes often narrow the possibilities before any roof covering is lifted.
The most helpful observations are lifted lead edges, cracked mortar where lead enters the brickwork, and staining just below one side of the stack. If you can describe those clearly, an inspection for chimney flashing problems is more likely to concentrate on the right part of the roof.
Different sides of the stack fail in different ways
The main possibilities are lead that has split with age or movement, poorly formed step flashings, and a chase that has opened in the masonry.
Other causes worth considering are previous repairs made with short-lived sealant, and failure of the back gutter behind the chimney. With chimney flashing problems, the important thing is to match the cause to defects in the lead or other weathering where a chimney meets the roof, rather than treating it as a general roofing fault. For chimney flashing problems, that distinction can prevent work being carried out on a nearby detail that happens to look worn but is not responsible for what you are seeing.
Old sealant can hide the real problem
From a safe position, you can view as much of the flashing as possible from ground level. You can also look for sealant patches that may hide an older defect.
It is also useful to check the loft for wetness on the same side of the stack. For chimney flashing problems, write down what you can see and, where relevant, what the weather was doing at the time. A short sequence of photographs of chimney flashing problems from the same safe viewpoint can show whether the condition is changing. When checking chimney flashing problems, avoid walking on the roof or leaning out of windows; the aim is to collect useful information without creating another problem.
Detached lead should not be left flapping
This becomes more urgent if lead is visibly detached, water is running in during ordinary rain, and mortar or masonry is loose around the chase. With chimney flashing problems, those signs suggest that waiting for a convenient time could allow more water entry, falling material or further damage.
If those warning signs are absent, chimney flashing problems may not need an emergency call-out, but it is still worth arranging a proper look before the condition gets worse. In this case, change over time matters: defects in the lead or other weathering where a chimney meets the roof that has been stable for a long period is a different situation from something that has appeared recently or is becoming more obvious after each spell of bad weather.
What needs checking all the way around the stack
A roofer looking at chimney flashing problems should inspect front apron, side step flashings and the back gutter as separate details, then check how far the lead is dressed beneath the roof covering.
They may also need to look for water entering above the visible flashing line. Because this page is about chimney flashing problems, the inspection should stay focused on that problem and the nearby details that could realistically produce it. For chimney flashing problems, ask what they think has failed, what evidence supports that view, and whether the proposed work is local or part of a wider defect. A clear explanation of chimney flashing problems is more useful than a quotation that simply lists materials.
Properly formed leadwork beats repeated patching
Depending on what is found, a suitable repair might renew failed leadwork to a properly formed detail, refix and weather the chase correctly, or avoid relying on surface mastic where the flashing itself has failed.
For chimney flashing problems, the best option is the one that deals with defects in the lead or other weathering where a chimney meets the roof and leaves the surrounding roof working as it should. If wider work is proposed for chimney flashing problems, ask why a local repair would not be reliable, what condition the adjoining materials are in, and whether access costs make it sensible to combine closely related repairs. The answer should make sense for chimney flashing problems, not read like a standard reroofing recommendation.
This guide is general information about chimney flashing problems. The cause of chimney flashing problems at an individual property can only be confirmed by inspecting the relevant roof area.