Base flashing is a continuation of the roofing membrane that is typically applied separately from the field application. The components, made of sheet metal, include cap flashing or counterflashing, which is applied to shield the exposed portions of the base flashing or to extend into the wall to divert any interior water to the exterior of the wall. Metal copings are used to seal and waterproof the top of a parapet or building wall. Edge flashings are used to hold the gravel in place on a ballasted roof or to finish off the edge of other types of roof. Expansion joints are structural separations that accommodate movement between two building elements, or at specific locations, such as where the roof deck changes direc- tion.
Scuppers create an exit for water through a parapet wall or an elevated edge.
Each of these metal flashing components require equal design consideration. Roofing details rarely come from architects fully thought-out, he says. They tend to fall back on the manufacturer s guidelines, which are generalizations, not job-specific details. Architects must take those generalizations and adjust them to the characteristics of the building. There is no such thing as a typical roofing detail.