Flashing is a construction detail used to seal and protects joints in a building from water penetration. The joints created by the intersection of the roof and roof mounted structures and projections, such as parapets, hatches, skylights, chimneys, vent stacks, or towers, are among the most vulnerable areas of roofing systems.
Flashing is used at these intersections to keep rainwater from leaking into the building.
Flashing is installed at intersecting roofs and parapets and walls. It typically consists of angled strips of corrosion- resistant metal that overlap in such a way as to discourage water entrapment.
The primary purposes of flashing is to collect, control, and discharge water. There are many areas in the building envelope where flashings should be installed. Simply stated, Flashing should be installed where materials stop, start, or change directions.
Flashings should discharge water out of the wall or off the roof with a path to daylight.