Copper flashing is a roofing material that acts as an extra layer of protection from leaks between roofing tiles and the rafters. One installs copper flashing, as opposed to aluminum or steel flashing, because it is more durable. For those concerned about aesthetics, copper flashing takes on a dark, greenish patina when exposed to air that some find attractive.
In general, flashing must be installed on parts of the roof where shingles can't provide enough of a barrier to water. These areas would include where slopes meet, such as at a ridge or valley; the space around units installed in the roof, such as air conditioners, fans, and skylights; and eaves where the edge of the roof meets the gutter system along the perimeter of the house. When properly installed, flashing helps to fight heavy water flow, the weight of snow, or precipitation during heavy wind fighting to get underneath shingles.
Investing in copper, a more expensive metal than galvanized steel or aluminum, is worth the durability. It can also be less time consuming to install because copper is a soft metal that's easy to form and bend into the appropriate shape. Installers don't need as many specialty on-site tools, so they are likely to charge less for their labor.
Copper flashing allows numerous methods of installation, because it comes in large rolls that can be trimmed into many shapes. The sheets of copper flashing can be formed into sculpted molds to exact dimensions of unusual shapes. But different sheets can also be soldered to create strong seams, or overlapped in a watertight pattern like tiles.
Copper flashing has been strongly recommended for use in certain applications. Use it in structures routinely exposed to the salty air of an ocean climate, because it is less likely to corrode. It is also ideal for use under woodshake, ceramic, or slate tile, where more of the flashing might show, because the metal is a complementary color. You must use this flashing near masonry structures, like brick or river rock chimneys, because other metals will corrode when coming in contact with the mortar.