Leadwork

Getting leadwork detailed correctly

Panel size and code decide the lifespan. Lead expands and contracts substantially with temperature, so panels must be sized to the code (thickness) used and fixed to allow movement. Oversized bays are the single most common cause of splitting, and they usually fail long before the metal is worn out.

Ventilate beneath the lead. Warm, moist air reaching the underside condenses and corrodes the sheet from below – underside corrosion is a frequent cause of premature failure on re-covered roofs. A ventilated substructure and a suitable underlay are part of a proper specification.

Ask which code and which method. Milled lead to BS EN 12588 in the appropriate code, laid with welts, drips and rolls suited to the pitch and exposure, is the standard; sand-cast lead is used on high-status historic work where matching the original matters.

Consider security and access. Lead theft remains a real risk on churches and isolated buildings, and insurers frequently require marking, alarms or a coating; some jobs justify a substitute material where insurers refuse cover, which is a conversation to have before the specification is fixed.