If a roof leak in Cromer is tracing back to a chimney, dormer or valley, the culprit is almost always the lead flashing - and getting it properly repaired starts with knowing what good lead work actually looks like from first inspection to finished job.
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Lead is the material of choice for sealing the joints where a roof meets a vertical surface - around chimney stacks, along dormer cheeks, in valley gutters, and at flat roof edges. When it is cut, dressed and fitted correctly, it creates a watertight seal that can last for several decades. When it is not, water finds its way in at exactly the point where roof meets wall, and the leak can travel a long way before it shows up on a ceiling inside.
Poorly dressed lead is behind more roof leaks than most homeowners realise. A common problem is lead that has been laid flat rather than properly dressed into the joints, or that has been bonded with sealant as a shortcut instead of being cut to fit. Sealant shrinks and cracks. Properly fitted lead does not.
A lead work job follows a clear sequence. Understanding what each stage involves helps you know whether the work being done on your roof is being carried out properly - and gives you the right questions to ask.
Before anything is touched, the area is inspected properly - from the roof, not just from the ground. On a chimney, that means checking the lead soakers under the side flashings, the stepped flashings themselves, the cover flashing at the front (the apron) and the back gutter or back flashing behind the stack. Each of these pieces can fail independently, and a fault in one can mask a fault in another.
On a dormer, the cheeks - the vertical sides - are checked for cracking or lifting, and the junction between the dormer roof and the main roof slope is assessed. On a valley, the lead lining is checked for splits, slipped sections or open joints where two roof pitches meet. The inspection stage should never be rushed, because a missed secondary fault means the leak comes back.
Old lead that has cracked, corroded or pulled away from the joint is removed completely. Patching over failed lead with new lead or sealant is a temporary measure at best. For the repair to last, the old material comes out. Where lead has been previously bonded with sealant, that sealant residue is cleaned back too, because new lead will not dress cleanly into a joint that is contaminated with silicone or mastic.
If the underlying brickwork or mortar joint has been damaged by water getting in over time, that is assessed at this stage. Repointing a chase in crumbling mortar before the new lead goes in is part of doing the job properly, not an optional extra.
Lead for flashings is supplied in rolls of different codes - the code number refers to the thickness of the sheet. Code 4 lead (1.8 mm thick) is widely used for step and cover flashings on chimneys. Code 5 (2.24 mm) is used in valleys and back gutters where water volume is higher and durability matters more. Using an underweight code is a false economy: thinner lead is more prone to cracking through thermal movement.
Each piece is cut to length on site, not pre-made to a standard template. Chimneys vary in width. Roof pitches vary in angle. The depth of the mortar chase that the flashing tucks into varies between properties. A flashing cut and formed to fit the actual dimensions of the job will always outlast one that has been bent to approximate the shape and filled with sealant to make up the difference.
For stepped flashings on a chimney, each individual step piece is cut separately to follow the line of the roof slates or tiles, overlapping the one below. The overlap between steps should be at least 75 mm to prevent water being driven under by wind.
Dressing is the process of pressing and shaping the lead into the mortar chase and over the surface it is sealing. A bossing mallet and dresser are used to form clean corners without splitting the lead. Splitting happens when lead is worked cold in winter - experienced roofers warm the lead gently before dressing in low temperatures rather than risk cracking it under the mallet.
The lead is tucked at least 25 mm into the mortar chase - ideally more on an exposed roof. It is then fixed with lead wedges driven into the joint to hold it in position, and the chase is repointed with a sand and cement mortar mix. The mortar seals the top edge of the flashing; the weight and fit of the lead itself does the waterproofing at the surface.
On valley gutters, the lead is dressed into the angle between the two roof slopes and turned up at the sides under the slates or tiles. The upstand - the height to which the lead turns up at each side - should be a minimum of 75 mm to cope with heavy rainfall. A valley with too low an upstand backs up in heavy rain and forces water under the adjacent slates.
Lead expands and contracts with temperature changes. A long, unbroken run of lead that has no allowance for movement will eventually crack or pull away from its fixing. The standard practice is to limit individual lead sections to no more than 1.5 metres in length, with a lapped or welted joint between each section to allow movement. On a long valley or a wide chimney back gutter, this means two or three separate pieces rather than one continuous strip.
This detail is one of the most commonly skipped on rushed or cheap lead work. If a flashing fails relatively quickly after being fitted, a lack of proper expansion joints is frequently the reason.
Lead work does not sit in isolation. The slates or tiles immediately around the flashing area are disturbed during the work, and any that were already loose, cracked or missing are identified at this point. Refixing or replacing a handful of adjacent slates as part of the same visit is practical and avoids a second call-out for something that was already failing. The area is also checked for any signs of underlying felt damage if the roof is stripped back enough to see it.
Once all the lead is dressed and the mortar has been pointed, the work is checked from the roof to confirm every joint is sealed and every step is correctly overlapped. Offcuts of lead, old mortar and any debris brought down during the job are cleared from the gutters and the area around the base of the house. Gutters blocked with mortar debris after a roofing job are a common complaint - a clean-up that includes the gutters is part of finishing the work properly.
Lead work covers several distinct tasks, each with its own materials and method. Understanding which type applies to your roof helps when getting quotes and checking the work.
Lead work pricing depends on the type and scale of the job. As a general guide for typical UK residential lead work:
These are indicative ranges based on current UK material and labour costs. The actual cost for your job depends on access, the condition of the underlying structure, and the extent of any associated tile or brickwork repairs needed. Any quote for lead work should specify the code of lead being used and describe which flashings are included - a quote that does not mention these details is one to query.
Catching a lead problem before it becomes a serious leak saves money on internal repairs as well as the roofing work itself. Look out for:
A visual check from the ground with binoculars is often enough to spot obvious lifting or cracking. However, identifying exactly which piece of flashing is failing - particularly on a four-sided chimney - usually requires getting onto the roof and checking each section directly.
We carry out lead work in Cromer and the surrounding area, cutting and dressing each piece on site to fit the actual dimensions of the job. Our work covers chimney flashings, valley gutters, dormer cheeks, flat roof edges and parapet flashings on domestic properties of all ages.
When you call us about a suspected flashing leak, we will arrange to inspect the roof properly and tell you clearly what we find, which flashings need attention, and what that work involves. If you want to know the code of lead we are specifying or why we are recommending a full re-flash rather than a patch, we will explain the reasoning in plain terms.
Call us to arrange a roof inspection in Cromer and get a clear, honest picture of what the lead work on your property needs.
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Call any time. Calls are answered day and night and passed straight to our roofers.
