What to check periodically
Periodic checks should cover the condition of rolls, drips and welted joints, along with any signs of lead theft or vandalism, which unfortunately remains a real risk for exposed lead roofs.
Patina vs actual problems
Lead naturally weathers to a grey patina over time, which is completely normal — the things to actually watch for are splits, lifted edges, or movement at the joints, not just colour change.
Extending the roof's lifespan
Addressing small issues — a slightly lifted edge, an early split — promptly is what keeps a lead roof performing for its full multi-decade lifespan rather than failing prematurely.