What lead flashing is, why chimney flashings fail, and what correct-specification replacement involves. Everything a Winchester homeowner needs to know.
Lead flashing is mentioned in almost every roofing survey report. Many Winchester homeowners know it is at their chimney but are unclear what it actually does, what the four elements are, or what correct replacement involves. This guide covers everything you need to know.
Every time a roof surface is interrupted — by a chimney stack, a dormer, a side wall, a skylight — there is a junction between the waterproof tile surface and a vertical element. Tiles cannot be lapped against a vertical wall to create a watertight seal. Lead flashing is the element that makes these junctions watertight. It is formed to fit exactly the profile of the junction, set into the masonry above and dressed down over the tile surface below, creating a seal that accommodates the movement of both elements without cracking.
The apron covers the junction between the chimney stack and the tile course directly in front of it. It is dressed over the tile surface and turned up the face of the chimney into a chase in the brickwork. The apron is the most visible lead element from the ground and often the first to be noticed when it fails.
Soakers are individual pieces of lead, one per tile course, set between each tile and the side of the chimney on both sides. They are hidden beneath the step flashings and interlace with the tile courses to create a stepped waterproof junction up both sides of the stack. Soakers that have not been fitted — a common shortcut — mean only the visible cover flashing is keeping water out at the sides, and it will fail faster as a result.
Step flashings are the visible stepped lead strips on both sides of the chimney, set into a raked chase in the masonry and dressed down over the soakers. They step up the roof slope following the tile courses. Step flashings set without soakers behind them — another common shortcut — look correct from the ground but lack the secondary waterproofing layer.
The back gutter is the lead tray behind the chimney stack, collecting water running off the upper roof slope. It is the most difficult element to see from the ground and the most common failure point on Winchester period properties. Back gutter failure causes water to track across the ceiling well away from the chimney — it is frequently misidentified as a ridge leak or a tile failure.
Lead is sold in codes that represent thickness and weight. Code 4 (1.8mm, 20kg/m²) is the minimum for cover flashings. Code 5 (2.24mm, 25kg/m²) is required for back gutters and valley linings. Code 3 lead in these positions — a common cost-cutting measure — fails 20–30 years earlier than correct-weight lead. Always ask what code is being specified.
There are three main causes. First, age — original Victorian lead on Winchester period properties is now 100–130 years old. At the correct specification and properly installed, lead lasts 60–80 years. Beyond that, it has reached end of design life regardless of condition. Second, underweight lead from previous repairs — replacing a failed flashing with code 3 rather than code 4 lead is common and creates a 20–30 year shorter lifespan for the replacement. Third, silicone patches — pointing silicone over a failed lead joint is the most common roofing bodge we find in Winchester. Silicone over lead is not a repair; it delays the correct repair by 1–3 years at most, after which the silicone cracks and the original failure is now worse.
We replace all four elements of the chimney lead set when any element has failed — not just the failed piece. This is because the remaining elements are the same age as the failed one. Replacing just the back gutter and leaving 100-year-old soakers and step flashings means a return visit in 2–5 years for those elements. We confirm the scope at survey and give you a fixed price for the full set.
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We survey and quote all four elements of chimney lead work in a single visit. No call-out fee.
📞 01962 809171The most common lead failure pattern we see across Winchester is back gutter failure on Victorian and Edwardian chimneys. Original lead in these positions is now 100-130 years old — at the absolute limit of its design life even if installed correctly. Back gutter failure causes water to track horizontally across the ceiling before appearing as a damp patch, often 1-3 metres from the actual failure point. It is consistently misidentified as a different roof problem.
Second most common: valley lead failure at extension junction junctions. Winchester's post-war housing stock has a high proportion of rear extensions added in the 1960s-80s, creating valley junctions between the original roof and the extension roof. Lead at these junctions was often installed below specification (code 3 rather than code 4) and is now failing across the estate housing areas of Stanmore, Winnall, Boyatt Wood and Badger Farm.
When getting a lead work quote, always ask the contractor to specify the lead code they are using. Code 4 minimum for chimney cover flashings and soakers; code 5 for back gutters and valleys. Any quote that specifies lead work without mentioning the code has not been thought through to the specification level required. Code 3 lead in a back gutter position will fail 20-30 years before correctly specified code 5 lead. The cost difference is marginal; the lifespan difference is significant.
We specify lead code on every Winchester lead work quote. Free survey, written fixed-price quote. Call 01962 809171.
How do I tell if my Winchester chimney has soakers fitted or not?
You cannot tell from the ground. Soakers are hidden beneath the step flashings. The only way to confirm their presence is to lift a step flashing and look beneath it. During a survey, we check whether soakers are present on all chimney stacks — their absence is a significant finding.
My Winchester chimney has been repointed but the lead was not replaced. Is this a problem?
Potentially — if the lead was left because it appeared sound, this may be fine. If the lead was left to save cost, the mortar work will outlast the lead and the stack will need attention again within 5–10 years when the lead fails. We assess lead condition independently of mortar condition at every survey.
Can I paint lead flashing to extend its life?
Patination oil (a specific product for lead work) is the correct treatment for new lead to accelerate natural patination and resist staining. Painting lead with standard paint is not recommended — it traps moisture and accelerates corrosion. Old lead beyond re-dressing cannot be extended with any coating — replacement is the correct approach.
How long does it take to replace chimney lead flashings on a Winchester property?
A full four-element chimney lead set replacement on a standard residential chimney stack: 4–8 hours for a one-person team with ladder access. Complex stacks, multiple stacks or difficult access add time. We confirm the work duration at survey stage.
Victorian terrace, Hyde — back gutter failure: homeowner reported ceiling damp below chimney breast, 1.5 metres from the stack. Previous contractor had repointed the chimney and replaced the front apron — damp continued. Survey confirmed back gutter failure. Water entering at the back gutter junction ran horizontally across the ceiling joist before appearing at the visible stain location. Full four-element lead replacement resolved the damp completely.
1930s semi, Chandler's Ford — step flashing failure without soakers: homeowner had had step flashings replaced 8 years previously by a previous contractor. Damp at the chimney breast recurred within 3 years and had been ongoing. Survey confirmed step flashings installed without soakers beneath — the visible step lead was present but without individual soakers, water tracked behind the lead at each tile course. Correct installation with soakers and new step flashings resolved the issue.
1960s semi, Eastleigh — code 3 valley lead: valley replacement carried out 15 years previously. Now failing. Survey confirmed code 3 lead installed rather than code 5 — 40% underweight for the application. Replaced with code 5 to BS 6915 specification. Expected service life 60–80 years. The cost difference between code 3 and code 5 on this valley replacement: approximately £80. The lifespan difference: approximately 40 years.
Lead flashing is the sheet lead used to waterproof the junctions between the roof and vertical elements — chimney stacks, dormer walls, abutments and parapet walls. It is the primary waterproofing at every roof penetration.
Correctly specified and installed lead (code 4 minimum for flashings, code 5 for valleys and back gutters) lasts 60–80 years. Lead installed below specification or bodged rather than properly replaced typically fails within 10–20 years.
Front apron (covers the junction between the chimney and the tile course in front of it), side soakers (individual lead pieces between each tile course on both sides), step flashings (stepped lead cover pieces set into the masonry on both sides), and back gutter (the lead tray behind the chimney that collects water from the upper slope).
Water staining on the ceiling near the chimney breast, damp plaster on the chimney breast wall, or visible gaps or lifting of the lead at the chimney base. Back gutter failure often shows as staining across the ceiling rather than directly below the stack.
Full four-element chimney lead set: £400–£800 on most Winchester properties. Complex stacks or conservation-area work costs more. Free survey and written quote.
No call-out fees. No obligation. An honest quote from a local roofer.
01962 809171