Issues · 6 min read
Chimney flashing issues on older Cobham homes — what to look for
Chimney flashing is the single most common source of leaks on 1930s Cobham semis. Here is exactly what to check for on your own home.
Why it fails
Original code-4 lead has a design life of about 60 years. Most Cobham 1930s stock has never been re-flashed — the lead is now 90+ years old and covered in pinholes invisible from ground level.
What to look for
Damp staining on the ceiling directly around the breast; tide marks running down the chimney brick externally; small mounds of white efflorescence salts on internal chimney walls. Any of these warrant a drone inspection.
Fixing it
Full re-flash in code-5 lead is £550–£950 including scaffold on a standard Cobham semi. A dressed lead patch of a single pinhole is £150–£220 as a same-visit repair alongside a roof clean.
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