Leadwork

Leadwork Explained

Reviewed by Martin, Select Roofing Services — Family roofers in Formby, Merseyside — 30+ years on the tools · Last updated August 2026

Lead chimney flashing — the most common leadwork job, and the most common failure point.

Leadwork gets less attention than tiles or slates, but it's arguably more important — every junction where a roof meets something else (a chimney, a wall, a valley, a dormer) depends on correctly specified and installed lead to stay watertight. This guide covers the British Standard that governs lead specification, why chimney flashing specifically fails so often, and what actually determines whether lead lasts decades or years.

Lead Codes Explained (BS 6915)

Rolled lead sheet manufacture is governed by BS EN 12588; installation and design is governed by BS 6915:2001+A1:2014, the British Standard that specifies bay sizes, joints, fixings and detailing for lead sheet roofing. Lead is supplied in numbered "codes" relating to thickness — getting the code right for the specific detail matters as much as the installation itself.

Code 4 is the most common specification for domestic chimney flashings and general use. The mistake to watch for isn't using lead at all — it's using too light a code for the exposure or the detail, which is a common cause of premature failure that has nothing to do with the material's genuine lifespan.

Why Chimney Flashing Fails First

Chimneys move slightly with weather, thermal cycling and age — more than most of the surrounding roof structure — and the lead flashing around the base has to accommodate that movement while staying completely watertight. This is a genuinely demanding detail to get right, which is exactly why it's also one of the most common places poor original work shows up years later.

The most common causes of premature chimney flashing failure: incorrect lead code specified for the exposure, sealant or mastic used instead of a properly dressed and fixed detail (a repair that looks fine for a year or two, then fails), and mechanical damage from previous chimney repointing work. See our chimney repairs guide for the full picture on chimney maintenance — leadwork and chimney condition are genuinely connected, and we assess both together on any chimney job.

Coastal Exposure & Code Selection

Formby, Southport, Crosby, Hightown, Ainsdale, Birkdale and Waterloo all sit close enough to the Sefton coast that exposure genuinely affects the right specification — this isn't a universal upsell, it's a real consideration a competent leadworker should assess per property, not skip. We specify to the actual exposure of your specific roof, not a blanket default.

Lead Welding vs Alternatives

Lead welding fuses sections of lead sheet together into a single continuous piece using specialist equipment — a more skilled, slower process than soldering or mechanical jointing, but one that produces a genuinely seamless joint that handles thermal movement better over the long term. Soldered or mechanically jointed lead can still perform well when done correctly, but welding is the superior choice for complex or bespoke details where a long-lasting, watertight finish matters most.

Repair vs Replacement

Not every leadwork problem needs full replacement. Localised lifting or a small split, where the rest of the lead is sound, can often be re-dressed and re-fixed rather than stripped out entirely. Where the lead has genuinely reached the end of its serviceable life, or was undersized for the application from the original installation, replacement to the correct code is the honest recommendation — we'll tell you which applies rather than defaulting to the more expensive option.

Our Process

1. Survey and diagnose — we identify the actual failure point, often not where the leak appears inside, and assess the existing lead code and condition.
2. Specify the correct code — selected to BS 6915 for the specific detail and exposure, not a default thickness for every job.
3. Strip and prepare — failed lead removed without damaging surrounding tiles, brickwork or stonework.
4. Dress and fix — new lead cut, dressed and mechanically fixed to specification, welded rather than soldered where a seamless joint is needed.
5. Inspect and guarantee — completed work checked and backed by our written guarantee.

Leadwork, Area by Area

We carry out leadwork across the whole of Merseyside and West Lancashire, with the same BS 6915-compliant, exposure-aware specification described on this page.

Frequently Asked Questions

Summary

Leadwork is one of the least visible but most consequential parts of a roof — the material itself, correctly specified and installed to BS 6915, will genuinely outlast most of what's around it. The failures that show up as leaks almost always trace back to the wrong code for the job, poor original detailing, or a sealant-based shortcut rather than a proper dressed repair. Get those right, particularly around chimneys where movement and exposure matter most, and lead becomes the most durable part of the roof rather than the weak point.

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