Where do extensions leave weak points?
The school was enlarged ten years after it was built, and the same story turns up on many houses: a lean-to, a rear wing or a porch added to the original. Wherever a newer roof butts against an older wall, a strip of lead should bridge the joint. One cost guide, updated in September 2026, puts lead flashing at over 80 years, but only if the wall behind it holds the fixings and the mortar is sound. We study each join first from the ground and then up the ladder, and the photos show you the exact spot. Our lead work page describes how flashings and valley linings are made.
A valley, where two slopes meet in an inward corner, deserves its own look. Leaves and moss build up there, the water has nowhere else to go, and a small crack in the lining shows up as a stain on a ceiling far from the roof edge. Clearing it and checking the lining beneath takes minutes, and it settles a lot of guesswork about where a leak starts.
Older buildings also carry chimney stacks, and a stack is where brick, mortar and lead all meet. Checkatrade's October 2026 guide puts chimney repointing at around £750 on average as a typical UK figure; for your stack the written price comes after we have seen the height, the access and the state of the joints. Our chimney repairs page goes through the options.