For centuries, copper has proved to be one of the best, most cost-effective architectural metals for corrosion resistance. Along with stainless steel and titanium, it often is used where corrosion is a major concern. Although no roofing material is perfect, copper can satisfy the demands of building owners, architects and contractors when it comes to lifetime economy, ease of fabrication, low maintenance and environmental friendliness.
There are thousands of examples of long-lived copper roof system and flashing installations, many well over a century old. Time has proved those buildings were constructed properly with careful thought to design, details and installation. But many factors can limit the potential life of metal roofing and flashings, one of which is corrosion.
The surface of any architectural metal will react when exposed to certain chemicals. Some chemicals are natural, such as those found in water from rainfall. Others are manmade, such as industrial pollution. How a given metal reacts to a chemical is related to the type of chemical, chemical's concentration and amount of time to which the metal is exposed to the chemical.