Sheet lead is a flat, malleable lead product manufactured by casting or rolling lead ingots into thin sheets, extensively used in construction for weatherproofing joints, flashings, gutters, and decorative roof detailing.
How it works
Lead has been used in construction for thousands of years due to its exceptional malleability, corrosion resistance, and longevity. Sheet lead is produced in various thicknesses, commonly designated by colour-coded standards. In the UK, for instance, BS EN 12588 classifies sheet lead by weight per square metre, with codes ranging from Code 3 (thinnest, at 1.32 mm) to Code 8 (thickest, at 3.55 mm). Each code is assigned a colour for easy identification on site.
The material’s softness allows it to be dressed by hand around complex shapes such as chimney stacks, dormer windows, valleys, and parapet walls. When properly installed, sheet lead forms a durable, watertight barrier that can last well over a hundred years with minimal maintenance.
Application in construction
Sheet lead is most commonly used for roof flashings, which are the strips of material that seal the junction between a roof covering and an abutting wall or penetration. Step flashings, apron flashings, and secret gutters are all typical applications. Lead is also used to line flat-roof areas, box gutters, and decorative features such as cupolas and spires.
Installation requires specialist lead-working skills. The lead is cut to size, shaped using lead dressers and bossing sticks, and fixed with lead clips or wedges set into mortar joints. Joints between sheets are formed using lead welts or lead-burned seams rather than solder, which can fail over time.
Builders must account for thermal expansion when installing sheet lead. Expansion joints and appropriately sized bays prevent the lead from cracking or fatigue-splitting as it heats and cools with changing weather. Health and safety protocols require dust control measures when cutting lead and thorough hand washing to minimise lead exposure.
Related terms
- Flashing
- Lead welding
- Roof valley
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