Leadwork & Flashing

Lead is the traditional material for roof flashings, valleys, chimney backs and parapet capping — and for good reason. Properly installed lead lasts 100+ years and remains the gold standard for period properties.

What is leadwork?

Rolled sheet lead (milled lead) used to weatherproof junctions and transitions on a roof:

• Flashing — joins between roof and wall/chimney/abatment
• Valley gutter — internal angle between two roof slopes
• Chimney back gutter — where chimney meets rear roof slope
• Apron flashing — joins roof to vertical wall
• Parapet capping — covers top of parapet walls
• Bay window roof — covers flat or pitched bays

Why lead?

• 100+ year lifespan — outlasts most other roofing materials
• Fully recyclable — sustainable choice
• Malleable — can be bossed (shaped) to fit any detail
• Self-healing — small scratches form protective patina
• Heritage-correct — the original material on Victorian/Edwardian properties

Lead codes (thickness)

Different applications require different lead thicknesses:

• Code 3 (1.32mm) — soakers under tiles/slates
• Code 4 (1.80mm) — flashings, apron pieces
• Code 5 (2.24mm) — horizontal flashings, chimney backs
• Code 6 (2.65mm) — valley gutters
• Code 7 (3.15mm) — flat roof bays, parapet cappings

We always specify the correct code for each application. Using thinner lead to save money is the most common cause of premature failure.

How we install leadwork (to BS 6915)

1. Measure and cut lead to correct dimensions (with 150mm minimum laps)
2. Form upstands, steps and welted edges as required
3. Fix with copper or stainless steel clips (NOT galvanised — they corrode)
4. Weld joins using traditional lead burning techniques
5. Patination oil treatment to prevent white staining on adjacent materials
6. Integrate properly with surrounding tiles or slates

Common leadwork problems

• Splitting at joints — usually thermal movement without proper expansion allowance
• Slipping — clips failed or absent
• Staining — lead run-off staining brickwork or render (mitigated with patination oil)
• Pinhole leaks — corrosion from acidic mortar contact
• Storm damage — high winds tearing flashing from chimney

Conservation area work

Most conservation areas (Wimbledon Village, parts of Putney, Carshalton Ponds) require leadwork on period properties — both for visual heritage and for longevity. We're experienced with Merton, Wandsworth and Sutton conservation requirements.

Cost guide

• Chimney flashing renewal (per chimney): £400-£800
• Valley gutter replacement: £80-£150 per linear metre
• Bay window roof: £600-£1,200
• Parapet capping: £100-£180 per linear metre