Chimney flashings, the correct build-up
A properly flashed chimney comprises four distinct components: soakers (small pieces of lead interleaved with each course of tiles or slates on the up-slope sides), stepped flashings or step-and-cover flashings (dressed over the soakers and stepped into the mortar joints of the chimney brickwork), an apron flashing on the down-slope face of the chimney, and a back gutter with a cover flashing on the up-slope face. Every one of these components has a role. Skipping any of them, as many older or amateur installations do, leaves a weakness that will eventually leak. We install the full build-up in Code 4 or Code 5 milled lead, chased into the brickwork, wedged with lead wedges, and pointed with a lime or sand-cement mortar as appropriate to the substrate.
Lead valley gutters
A valley is where two roof slopes meet at an internal angle, a huge catchment of rainwater discharges through it. We install lead valley gutters in Code 5 milled lead, laid over a boarded substrate, with correctly formed drips at maximum 1.5m intervals to avoid thermal-movement fatigue, tilting fillets to lift the tile edges clear, and correctly formed head and tail details. A valley detailed correctly will outlast the roof around it.
Abutment flashings
Where a pitched roof meets a wall, a lean-to, an extension abutting the main house, a garage against a boundary wall, the junction needs a stepped or straight cover flashing dressed down over the tiles and stepped up into the wall's mortar joints. We chase the flashing into the wall properly, wedge and point it, and dress it neatly over the tiles. Mortar-only 'flashings' at abutments are one of the most common causes of persistent leaks in older extensions.
Repair vs replace
Small splits and localised damage in otherwise sound lead can often be repaired by lead-welding (traditional 'lead burning'). Where lead has gone chalky-white through carbonation, has fatigue-cracked in multiple locations, or has been repeatedly patched, it's at end of life and needs replacing. We tell you honestly which category the lead work is in after inspection.
Why not just use flashband?
Bituminous flashing tape (flashband) has its place, as a very short-term emergency patch to stop water while a proper repair is scheduled. It is not a permanent flashing. It relies on adhesive that degrades in UV, its bond to the substrate breaks down within one to three seasons, and once it lifts, water is directed under it rather than shed over it. Every 'flashband' repair we're called back to is leaking. Lead, done properly, is done once.
