Apron flashing is a type of roof flashing that is used to protect the transition between a roof and a vertical wall or chimney. It is a piece of metal or other material that is installed between the roof and the wall to prevent water from infiltrating the building through this area.

Apron flashing is typically installed along the lower edge of the roof, where it covers the transition between the roof and the wall. It is often made of metal, such as aluminum or galvanized steel, although other materials can also be used. The apron flashing is bent and shaped to fit snugly against the roof and the wall, creating a barrier that prevents water from entering the building.

In addition to protecting against water infiltration, apron flashing also helps to prevent damage to the roof and wall from water or other elements. It is an important component of a well-constructed roof system and should be installed correctly to ensure its effectiveness. Poorly installed apron flashing can result in leaks and other damage.