Lead is the oldest roofing material still in everyday British use, and it survives because nothing else does its job as well. It can be dressed by hand into any shape, it lasts for generations, and it is the default for flashings, valleys, bay roofs, dormer cheeks and porch roofs on anything old enough to have them. It is also expensive, heavy, and worth stealing.
Where lead still earns its place
Flat and shallow bay and porch roofs, where a sheet can be dressed over a curve no membrane will follow. Valleys, where two slopes meet and the water concentrates. Chimney and abutment flashings, where the metal has to step with the brick courses. Dormer cheeks and tops. On a listed building or in a conservation area it is frequently the only material that will be permitted, because the alternatives look wrong and weather differently.
How a lead roof fails
Fatigue is the main enemy, and it is a design problem rather than a material one. Lead expands and contracts a great deal with temperature, and a bay that is too long between joints or fixed too rigidly will crack along the line where it has been flexing, usually within a decade. The second failure is the mortar joint holding an upstand into the wall, which weathers out and lets the flashing lift. The third is simple wear at the drip edges on very old work.
Repairs, replacement and theft
A split from fatigue can be lead welded by somebody who does that work, but if the bay is oversized the crack will return, so the real repair is re-dressing it in correctly sized panels with proper joints. Replacing lead on a large roof is expensive because the material is heavy, the labour is skilled and the scaffold is real. Where theft is the problem, forensic marking and alarmed fixings are common answers, and some owners replace stolen lead with a coated substitute where the position is not visible and the planning position allows.
Questions people ask about lead roof
How long does a lead roof last?
Correctly sized and dressed lead commonly outlasts the structure around it, and there is plenty of British leadwork more than a century old still in service. Badly sized lead cracks within a decade, which is why the detailing matters more than the age.
Can lead be replaced with something cheaper?
On a listed building or in a conservation area often not, and elsewhere it depends on the shape. Coated substitutes work on simple flashings and are much harder to dress into complex detail.
Is a lead roof safe over a living space?
Yes. Sheet lead on a roof is not a health risk to occupants; the concerns about lead relate to paint, pipework and dust rather than to roofing sheet.