flashing
n. C / Un. thin pieces of metal or other material used to stop water from getting into a building. You usually find it around windows, chimneys, or where the roof meets a wall.
n. strips of impervious material, typically lead, zinc, or plastic, installed at roof intersections or joints to prevent water penetration. Uncountable when referring to the material generally; countable when referring to specific installed sections.
The rain leaked through because the flashing was old.
The contractor replaced the lead flashing around the chimney to prevent further water damage to the attic ceiling.
Properly installed flashing is essential at every roof penetration, as even a minor gap in the metal stripping can lead to significant structural rot over several seasons.
From flash + -ing. * (weatherproofing): From original flashing material of copper or aluminum that reflects flashes of sunlight.
Often used with 'lead' or 'roof' as a modifier.