As landfill availability decreases and tipping fees increase, solid waste generators are becoming more interested in finding alternative ways of managing shingle waste. This site discusses the recycling of asphalt roofing shingles, or “composition shingles” including shingle quantities, composition, processing, products, and products made with recycled asphalt roofing shingles.
Asphalt shingle scrap can be used in a variety of products, including:
- Asphalt pavement,
- Aggregate base and subbase,
- Cold patch for potholes, sidewalks, utility cuts, driveways, ramps, bridges, and parking lots,
- Pothole patch,
- Road and ground cover,
- New roofing, and
- Fuel oil
Approximately 11 million tons of waste asphalt roofing shingles are generated in the U.S. per year. Re-roofing jobs account for 10 million tons, with another 1 million from manufacturing scrap. California is estimated to generate 1.2 million tons per year, of which 1.1 million are tear-offs from re-roof jobs. Asphalt roofing comprises roughly 1.7% of the state’s disposed waste stream (2018), these quantities may fluctuate with the construction industry, and with natural disasters such as floods and earthquakes.
Asphalt roofing shingles are made of a felt mat saturated with asphalt, with small rock granules added, and are described as follows:
Asphalt cement: 19 to 36 percent by weight. Asphalt used in shingles is considerably harder than asphalts used in pavement.
- Organic shingles contain 30 to 36 percent asphalt.
- Fiberglass shingles contain 19 to 22 percent asphalt.
Mineral filler/stabilizer (limestone, silica, dolomite, etc.): 8 to 40 percent (90 percent is smaller than .15 mm, 70 percent is smaller than .08 mm.)
Mineral granules (ceramic-coated natural rock, sand-sized): 20 to 38 percent.
Felt backing (mat): 2 to 15 percent. There are two types of mats:
- Organic felt, made with paper (cellulose).
- Fiberglass felt.
Waste Stream Composition
Shingles in the waste stream can be either old or new.
Old Shingles. The majority of waste shingles are tear-offs from re-roof jobs or demolition debris. The load may contain contaminants, such as nails, and wood if the underlying plywood is also replaced. Roofs are replaced roughly every 20 years. Old roofs are often overlaid with new shingles, so some tear-offs contain a 20-year-old layer plus a 40-year-old layer. Twenty to forty years ago, most shingles contained organic mats.
New Shingles. After most shingles are manufactured, tabs are cut out to shape the shingles for assembly. These tabs contain fresh asphalt. Also discarded are new shingles that did not meet quality standards. Today, most new shingles contain fiberglass mat.
To prepare shingles for use in new products, the shingles must be ground to a specified size, and contaminants removed.
Grinding may be easier in the winter when the asphalt is more brittle. If the shingles begin to stick together in hot weather, or from the heat of the equipment, spraying with water or blending with sand or gravel may help.
Depending on the equipment used, primary grinding may yield 2″ or 3″-minus size pieces. Secondary grinding may be required to make smaller pieces if needed; for example, aggregate base may require 3/4″-minus, and asphalt pavement may require 1/2″-minus or 1/4″-minus.
Depending on the use, the shingles may have to be sieved after grinding, to conform to grading requirements.
For virtually all uses, contaminants must be removed. Possible contaminants may include:
- Metals, which can be removed by a rotating magnet.
- Wood, which sometimes accompanies shingles when the plywood is also replaced in a re-roof job. Wood can be removed by hand, or floated off in a water flotation unit.
Asbestos is no longer used in the manufacture of asphalt roofing shingles.
The incidence of asbestos-containing shingles in roof tear-offs today is extremely low. The total asbestos content of asphalt shingles manufactured in 1963 is only 0.02 percent; in 1977, it dropped to 0.00016 percent. Due to the practice of covering a worn out roof with new shingles, there may continue to be a very small amount of asbestos in the shingle waste stream until about 2016.
The agencies regulating asbestos are the U.S. EPA, CalEPA (Air Resources Board and Department of Toxic Substances Control), federal Occupational Safety and Health Administration (OSHA), CalOSHA, and city and county health departments. U.S. EPA and CalEPA regulate friable asbestos over 1 percent. OSHA regulates friable and nonfriable asbestos over 0.1 percent. Processors would need to contact these agencies to determine permitting and test monitoring requirements, if any.
Most processors improvise by modifying simple equipment. A hammermill will grind shingles, though it works best with the softer aggregates, such as limestone, rather than granite. Following is a partial list of manufacturers that sell equipment that can grind asphalt shingles.
Siting a shingles recycling plant may require certain State and local permits, such as air, water, zoning, and possibly solid waste.
Where Can I Get Help?
Businesses starting or expanding into recycling activities may get financial, technical, marketing, business and permitting assistance from the “Zone Contacts” at CalRecycle, at (916) 341-6199
- Air Permits
The local air districts may be concerned about nuisance odors and various emissions, and may require processors to spray with water to control dust. The local district may also want certification that the incoming loads have been tested for asbestos. Locate your local air district by calling the Air Resources Board at (916) 322-2990 or check their Web site.
- Water Permits
Your Regional Water Quality Control District may need to permit the facility depending on feedstock and location. The Regional Board may distinguish between old shingles with hard asphalt and new shingles with fresh asphalt. Look up your district in a local phone book under State Government, Water Quality Control Board or check their Web site.
- Solid Waste Permits
The CalRecycle developed a tiered permitting system for the transfer and processing of construction demolition and inert materials (CDI); several categories may require less than a full permit. Contact your Local Enforcement Agency (LEA) for projects specific permitting guidance. To find out who the LEA is for the project area, check the CalRecycle’s LEA Directory.
All new asphalt roofing shingles manufactured in California are fiberglass-based, and are produced at the following plants:
Fremont, Alameda County
Los Angeles, Los Angeles County
GS Roofing Company, Inc.
Southgate, Los Angeles County
Wilmington, Orange County
Compton, Los Angeles County
Richmond, Contra Costa County
GAP Materials Corp.
Fontana, San Bernardino County
Shafter, Kern County
Construction and Demolition Recycling Association (CDRA)
Asphalt Roofing Manufacturers Association
6000 Executive Blvd.
Rockville, MD 20852-3803
To download or order publications, and to see a complete publications list, go to the CalRecycle Online Publications Catalog.
Free Directory of Construction Industry
The Blue Book–Building & Construction