Materials, thickness, and Shape:
ARCO Metal manufacture as per your specification. But as per International Building Code IBC, our recommendation is metal flashing from galvanized steel with minimum thickness OS mm.
1503.2 falshing :
Flashing shall be installed in such a manner so as to prevent water from entering the wall and roof through joint in copings,through moishtre-permeable materials and at intersections with parapet walls and other penetrations through then roof plane.
Flashing shall be installed at wall and roof intersections, at gutters,wherever there is a change in roof slope or direction and round roof opening. where flashing is of metal, the metal shall be corrosion resistant with a thickness of not less than 0.019 inch ( 0.983 mm ) (No.26 galvanized sheet).