The use of copper flashings, gutters and leaders is desirable, and indicates substantial construction, although good galvanized iron, if well painted, is extremely durable and gives excellent results, and is most commonly used in six-story buildings or those of lesser height.

If a plastic slate roof is used, plastic slate may be used for flashing. It is most important to have the roof watertight, and the flashing of the roof is one of the most necessary things to have done properly. To make a thoroughly good job of flashing, where metal is used, the flashing should be continued completely through the brick work or coping wall, and all plumbing pipes running through the roof should pass through a lead collar and sleeve, made fast to the roof covering, and flashed with copper and then counter-flashed - i. e., a cap flashing run around the pipe some six inches above the roof.

Where plastic material is used for flashing, the higher the fire walls are flashed the better the result.