The horizontal top surfaces of walls are the most vulnerable point for water to enter the wall. There are a number of ways of protecting this surface with metal flashing alone, or in combination with stone or precast concrete. In general, metal flashing for copings comes in lengths of 8 or 10 feet. Adjacent sheets are joined with standing seams or transverse seams that are locked and/or soldered.
On roofs with short parapet walls, positive roof drainage must be provided. The water level on the roof must not reach any point where the the roofing membrane terminates or has been punctured, such as at cleats.