When building meterials intersect, there is the potential for water infiltration. Flashing is a thin material used to prevent water penetration by providing a seal at joints exposed to the water.
Flashing prevent moisture from penetrating into masonry walls where the wall intersects the roof. Internal flashing, or concealed flashings, catch water that has penetrated a masonry wall and drain it through weep holes to the outside of the wall
Additionally, internal flashing is required at any location where the cavity is interrupted, such as the heads of windows or doors, and window sills.
Flashiing is also categorized by the material that it is made from, as well as the location of the flashing within a building structure, such as at roof valleys or at chimneys.
