Shingle manufacturers have worked with zeal to protect their share of the roofing markets within the industry’s emerging green building environment. Traditional estimates peg asphalt shingles as supplying more than 75% of the roofing market, with some industry analysts saying it’s as high as 95%.
With that in mind, roofing manufacturers have upgraded the energy performance and resource efficiency of their products. Today’s shingles incorporate new attributes, including cool-roof performance, recycled content, and end-of-life solutions that can contribute to greening new and existing homes. This article explores the greenest asphalt shingle options available today and the highly successful initiatives in place to recycle the millions of tons of shingles torn off buildings every year.
Anatomy of a Shingle
Until about 10 years ago, roofing shingles were sold in two dominant varieties, organic and fiberglass. The organic part of asphalt shingles was a cellulose fiber substrate, often recycled paper, impregnated with asphalt that provided the shingle structure. Today, 95% of asphalt shingles manufactured are reinforced with a glass mat instead of paper and are called composition, or comp, shingles. Manufacturing improvements have made today’s composition shingles highly wind and impact resistant, quick to seal even in cold weather, and better looking, too.
The anatomy of a modern asphalt shingle starts with a highly engineered glass mat at the heart of the shingle, providing greater strength and requiring less asphalt than an older, paper-based organic shingle. This nonwoven, multidirection chopped glass mat resembles the structural composition of oriented strand board. “The glass strands are laid out in multidirectional fashion, providing all angles of strength,” explains Tony Ruffine, vice president of sustainability and strategic marketing at GAF, the nation’s largest shingle manufacturing company. This glass mat comes sandwiched between two layers of asphalt.
The top layer of asphalt is coated with stone granules that give the shingle color and protect it from ultraviolet rays and weathering. This refined, granite-like coating comes from basaltic deposits, including basalt and rhyolite, which are not only hard and durable, but opaque to keep UV rays from deteriorating the asphalt. Progress in granule technology has prolonged a shingle’s life from an average of 20 years to the now common 30, 40, and even 50 years. Granules are painted using a semi-ceramic process, similar to firing glazes on clay, but at lower temperatures. Made by only a few companies in the United States, these granules are also engineered to reflect infrared heat and keep roof temperatures cool. They also may contain additives, such as algaecides.
The area of shingle under the overlay row of shingles is called the head-lap, it’s the gray-black part of the shingle above the nailing strip. If a shingle boasts recycled content, here’s where the bulk of it comes in. The head-lap granules may come from coal slag, a power plant waste product. Recycled content varies with the manufacturing plant, so you must check with local resources to see which shingles in your area have the highest percentage.
The remaining critical components in a shingle include the adhesive tabs along the bottom of the shingle and at the nailing strip. These mechanical and chemical attachments lock shingles to the roof deck and fuse shingle courses as the sun warms the roof, melting the adhesive tabs. This combination of nails and thermal adhesives, along with the rip tolerance of the shingle, provides the product’s wind resistance. Most shingles meet a minimum 60 mph wind speed rating, but higher-grade shingles, such as GAF’s Timberline ArmorShield II, can carry wind ratings of 130 to 150 mph. This may speak to quality more than ecology, but keep in mind that when hail and windstorms hit, hundreds of roofs are damaged, then removed and replaced. Durability is one definition of ecological economy