When you want to add beauty and interest to your home’s exterior, consider using copper. While copper is quite pricey, used as an accent, it can make a strong impression. You’ll rarely see copper used over an entire residential roof More often, homeowners choose accents, bay windows, dormers, or other areas where they desire a touch of elegance. Sometimes you’ll find copper on institutional buildings, Banks, Universities, Church steeples, cupolas, and the like.
Copper comes in varying weights and thicknesses: 12 oz. (0.016”) and 16 oz. (0.022”) are common for preformed shingles, 16 oz. (0.022”) and 20 oz. (0.027”) are common for vertical seams. Because it is considered a precious metal, copper is measured (and priced) by the ounce.
Copper is a heavier metal, typically weighing between 150 and 200 lbs per square (one square = 100 sq. ft.).
Installing Copper
Copper is typically installed in short, standing seam panels or sheeting but is also available in shingles. Sometimes, copper serves as a flashing material in conjunction with other roofing materials, but that is not a recommended use with aluminum or steel roofing for three reasons. First, most residential metal roof systems come with preformed flashings, and second, when copper is left in direct contact with a dissimilar metal, it will speed up the deterioration of the other metal through galvanic action. And finally, as the copper patinas, the water runoff tends to stain other metals, brick, concrete, and almost anything else with which it comes in contact. It is important to understand where the water runoff over a copper portion of a roof is directed and channeled off the roof. One solution is to use lead-coated copper as a replacement for pure copper. However, there is a trend toward avoiding lead in all building products due to safety concerns.
Understanding the patina process
Copper is best known for the attractive blue-green, or verdigris patina that forms when copper is left exposed for 8-15 years. The actual time it takes to patina depends on what is in the air; salt spray in a coastalenvironment, for example, dramatically hastens the process. The patina works like a barrier against corrosive elements and is part of the reason for copper’s extremely long life. While treating copper can speed up or slow down the patina process, most homeowners elect to allow copper to weather naturally to ensure the rich, luxurious verdigris look.
Because copper is relatively soft and malleable, it is fairly easy to work with and usually solders well. Copper is also extremely durable and has a long life – sometimes more than 100 years. Copper has been used extensively for hundreds of years in the United States.
Fun fact: one of the first applications was the Massachusetts State House. The copper for this project was one of the first orders for Paul Revere’s newly founded copper rolling mill, in 1801.
