Chimneys are the most vulnerable part of the roof. All chimney components need to be in place for the chimney area to function properly.
Faulty flashing is frequently to blame for roof leaking at chimney. Chimneys are protected from moisture penetration with flashing. The flashing is the sheet metal that keeps the intersection between the chimney and roof water-tight. Proper flashing around a chimney includes two components, step flashing – where sections of L-shaped sheet metal are woven into the shingle course and lapped up the side of the chimney, and counterflashing – where the second component of metal is embedded into the chimney mortar joints and folded down to cover the top of the step flashing.