Copper offers a character and durability that no other metal can match.
Its appearance can complement any style of architecture from the traditional to the modern.
Its warmth and beauty make it a preferred material for builders, contractors and architects.
The use of copper is based upon traditional practices proven over time, which is why it is commonly found on roofs of European cathedrals, Japanese temples and shrines dating back hundreds of years. There are numerous examples of copper roofs that have lasted one or more centuries. Copper’s resistance to the elements ranks among the highest of modern roofing materials. Unlike other metals, copper’s ability to develop protective corrosion products, what most people know as patina, makes it extremely long lasting in nearly all natural environments.
Each year high winds cause billions of dollars of damage to buildings. With that in mind, architects and contractors have a benchmark specification for roofing that meets the most demanding wind conditions. Standing-seam copper roofing is rated for resistance to the highest winds in Underwriters Laboratories’ tests: U.L. Wind Uplift Class 90.
High resistanceAlthough specific testing and safety procedures must be taken into consideration, a product that passes UL-90 testing has passed a simulated test of winds up to 188 mph. While it is important that these materials pass laboratory testing, proper installation of any roofing product is critical to its performance in high winds.
In the past, standing-seam copper roofing has met or exceeded the criteria of the demanding tests for uplift resistance at independent laboratories, and many architects have specified it based on these tests. Prestigious U.L. certification is especially relevant because the roof is a critical part of a building’s structure. When a building’s roof is compromised, what is left cannot always sustain the catastrophic damage caused by wind and rain.
The eaves of a roof are a general concern with regards to high winds. They are a very susceptible part of the building’s exterior, and in many cases, it is the ability of eaves and other roof edges to withstand negative pressure forces that prevent roofing from being peeled off during high-wind conditions.
For this reason, it is recommended that a continuous edge strip should be used to secure the lower edge of the eave flashing. The strip should be nailed to a secure part of the roof, fascia or eave with nails spaced no more than 3 inches apart in a staggered pattern.
Damp dangersIn areas with high wind and rain, moisture can also pose a threat. Moisture that penetrates the roofing system and leaks into a building could cause serious damage to its interior. In freezing temperatures, it can also wreak havoc to the building’s exterior, resulting in cracking and disintegration. Over a long period of time, moisture can weaken the structural elements of the entire building envelope.
Most modern construction materials are resistant to moisture penetration. However, many joints between masonry units, panels or architectural features are not. The effects of natural movement due to settlement, expansion, and contraction tend to compound the problems and may eventually lead to leaks. Flashing is used to prevent moisture from entering at such locations. It is also used to divert to the exterior moisture that has already entered various components of a structure.
Copper is an excellent material for flashing because of its malleability, strength, and high resistance to the caustic effects of mortars and hostile environments. Flashing, in general, is expensive to replace if it fails, so a material with long expected life, like copper, is a major asset in this application.
While numerous examples point to copper roofing lasting for centuries, various estimates conservatively set the lifespan of a copper roof at more than 100 years, while asphalt shingles - the most commonly used roofing material in America - are typically said to last 15 to 30 years, on average. This makes copper one of the most cost-effective roofing materials on the market.
Green with durabilityOne reason for its longevity is the natural blue-green patina that develops with age and serves as a protective shell when exposed to the elements.
In addition to its attractive patina, copper is environmentally friendly, boasting one of the highest recycling rates of any engineering metal. Because of its inherent value, copper building products are typically salvaged and recycled. This not only reduces the amount of building products destined for the landfill at the end of the building life, but also decreases the raw material needed for future copper products.
Copper roofing sheet is predominantly made from copper scrap and it is one of the most thoroughly recycled among what we might call structural metals. Most people don’t realize it, but nearly one half of the copper used in the U.S. today has been used before. Worldwide numbers are about the same.
Other key attributes of this premium metal are its fire resistance and ability to withstand excessive temperatures.
This article was supplied by the Copper Development Association. For more information on copper roofing, applications, tests, procedures and standards, visit its website, www.copper.org.www.copper.org.
For reprints of this article, contact Jill DeVries at (248) 244-1726 or e-mail firstname.lastname@example.org.