Pry, chisel and scrape off old metal flashings and roofing cement. Before you do anything, get your ladder, roof brackets and safety harness set up so you can work safely and efficiently on the roof.

Asphalt, wood shakes, slate and other overlapped roofings are fine until they meet an obstruction. Up against a dormer, a vent pipe, a chimney, they need flashing — a patchwork of metal sheets, and ...