When lead flashing starts to fail on a Bowthorpe property, the real decision is whether a targeted repair will hold or whether a full replacement is the smarter call - and getting that decision right saves money in the long run.
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Lead flashing is the dressed metalwork that seals the junction between a roof covering and any vertical surface rising through or against it - chimney stacks, dormer walls, parapet copings, and abutment walls where an extension meets the main house. When the seal fails, water runs behind the tiles and soaks into the roof structure. The damage can be well advanced before a stain appears on a ceiling.
Lead fails for a handful of predictable reasons. Thermal movement over many years causes cracking at the bends where the lead has been dressed into shape. Mortar in the chase or raglet (the slot the lead tucks into) can shrink, crumble, or was never properly raked out in the first place, allowing the top edge to lift. In older properties, a previous contractor may have simply laid a bead of mastic sealant over the original joint rather than cutting and fitting new lead - that sealant typically lasts two to four winters before it opens up again.
Not every lead problem needs a full strip-and-replace. Equally, not every problem is worth patching. The right answer depends on three things: the age and overall condition of the existing lead, the extent of the failure, and whether the underlying structure is sound.
A targeted repair is appropriate when the lead itself is in reasonable overall condition but has failed at a specific point. Common candidates for repair include:
In these cases, a repair costs less and causes less disruption. A repair on a single chimney side flashing might cost £150 to £300 depending on access and the extent of repointing needed. That is a sensible spend if the rest of the flashings are sound.
Replacement becomes the right call when the existing lead has reached the end of its serviceable life or when a repair would be a false economy. Situations that call for full replacement include:
Full chimney flashing replacement - front apron, step flashings on both sides, and a back gutter - typically costs in the region of £400 to £800 for a standard stack, depending on the size of the stack and the complexity of the roof pitch. A full lead valley replacement on a longer run may be £600 to £1,200 or more. These are typical UK figures; the actual cost depends on access, the lead code required, and whether any underlying repair is needed at the same time.
Choosing a cheap patch repair on lead that is genuinely at end of life means paying twice - once for the repair that fails, and once for the replacement that should have been done first. The second bill also arrives after more water has entered the roof, potentially with timber or plaster damage added to the cost.
On the other hand, replacing perfectly sound lead because a contractor has not looked carefully enough is an unnecessary spend. A thorough assessment should include checking the pliability of the existing lead (brittle lead cracks when bent; sound lead bends cleanly), measuring the thickness if there is any doubt, and inspecting the full length of every run rather than just the obvious failure point.
Before recommending repair or replacement, we get on the roof and look at the whole junction - not just the section that has visibly failed. We check the chase depth, the condition of the mortar, whether the lead has been fixed to the correct code for the application, and whether there are secondary problems such as slipped tiles or failed underfelt nearby.
We then explain what we found and give you a clear recommendation with honest reasoning. If a repair is genuinely the right answer, we say so. If the existing lead is beyond reliable repair, we tell you why rather than just quoting for replacement without explanation.
Lead is sold and specified by code, which refers to its thickness and weight per square metre. Code 3 (1.32mm) is too thin for most external roofing applications and should not be used for flashings. Code 4 (1.8mm) is the standard minimum for chimney flashings and general use. Code 5 (2.24mm) is correct for valleys, parapet gutters, and wider applications where more material is needed to cope with water volume and movement. Using the wrong code is a false economy - under-weight lead thins faster and cracks sooner.
When you are comparing quotes, ask each contractor which code they are specifying and for which parts of the job. The answer tells you a great deal about whether they are doing the job properly.
If you are unsure whether your lead flashing needs a repair or a full replacement, call Poringland Roofers and ask for a lead work survey. We cover Bowthorpe and the wider Norwich area, and we will give you an honest assessment before you commit to anything.
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Call any time. Calls are answered day and night and passed straight to our roofers.
