A sustainable roof must first be simply a good roof. Charged with the critical role of keeping the weather outside a structure, dependability is the most essential feature of a roof.

Roofing materials comprise 12 to 15% of construction and demolition waste. A well-installed 50+ year rated roof can:

• Reduce roofing waste by 80 to 90% over its lifetime, relative to a roof warranted for 10 or 20 years.
• Further reduce waste by protecting interior materials from water damage and potential for mold.
• Keep insulation dry; most insulation is less effective when wet (with the exception of closed-cell foams).
• Save resources. It takes roughly the same materials, energy, and labor to manufacture and install a 50-year warranted roof as a 15-year roof.

Other key considerations include:

• Color: Better reflection of solar radiation with lighter colors (more precisely, high reflectivity) reduces heat gain and improves summertime comfort.
• Insulation and radiant barrier: Some roofing options incorporate additional insulation or radiant barriers, helping to maintain comfort and reduce ongoing energy use.
• Weight: Heavier roofing requires a more substantial structure, and larger or more numerous support members increase resource use and cost.
• Recycled content: The resistance to water, sun, pests, and chemical breakdown that make tires, rubber, and many plastics poor candidates for disposal in our landfills also help these materials perform brilliantly as roofing. The CIWMB Recycled Content Product Directory can help you find literally dozens of roofing products with more than 50% post-consumer recycled content and excellent warranties.
• Recyclability: Even the most durable roofing will eventually need to be replaced. For example, asphalt composition shingles and some plastic products can be ground up and recycled into new roofing, or into asphalt pavement (ideally keeping the material out of the landfill permanently).
• Water quality: Sediment or noxious chemicals released by many petroleum-derived roofing products are undesirable in rainwater collection systems.

The extraction, manufacture, transport, and disposal of roofing materials pollutes air and water, depletes resources, and damages natural habitats. According to the California Integrated Waste Management Board, construction and demolition are responsible for 28% of California's solid waste stream and more than 85% of that material, from flooring to roofing, is reusable or recyclable. Some roof materials, such as rubber or composite can leach contaminants and are thus inappropriate for potable water collection; check with manufacturers. The benefits of environmentally preferable roofing materials include reduced landfill waste, reduced energy use, aesthetically pleasing design options, and reduced impacts from harvest or mining of virgin materials.

See the following sections in this guide: