Dear Umbra,

Our roof is getting pretty old and starting to fall apart. It’s one of those asphalt-shingle roofs that most houses have these days. Before we call the roofing company, I’d like to know what’s the greenest kind of roofing material to use. Metal? Cedar? More asphalt? I’m sure lots of other readers would like to know, too!


Wally Bubelis
Seattle, Wash.

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Dearest Wally,

Like other readers, you may need a drink or two to wade through the perplexing nexus of budgetary, aesthetic, and environmental concerns involved in making sustainable-building decisions. It sounds to me like you’re looking for a life-cycle analysis of roofing materials, and none of the knowledgeable folks I spoke with could provide one. In other words, there is no way that I can answer your question. No, I’m not wimping out. Even my friend at Northwest Eco Building Guild says there is no clear answer. Let me explain:

It’s roof, roof, roof for the home team.

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Your asphalt roof lasted maybe 30 years. When you dismantle it, it could probably be partially recycled into pavement, but you’ll have to call around to roofers and recyclers to see if this is an option in your area. Asphalt-shingle roofs are cheap and easy to install. Another cheap option would be a metal roof, which lasts for decades and amplifies the pitter patter of little rain drops. Although its manufacture may be energy-intensive, you may be able to find metal material with recycled content, and then recycle the roof when you’re done. (Although, not to be morbid, a metal roof may last longer than you do.)

Other options: Cedar shingles may work for your roof’s pitch and weather demands, and in your West Coast eco-city, it’s possible to find sustainably harvested cedar certified by the Forest Stewardship Council, or salvaged from stumps left behind after logging. You could look into getting a thatch roof, or make an earthen plaster one. It is also possible to make a living roof, a roof covered with a layer of soil and growing plants. Sounds wacky, but homes and businesses are installing them around the country. Living roofs have excellent heating and cooling properties and they reduce storm water runoff.

How to choose? For starters, look for longevity of the material you use and its recycled or renewable content. All materials, even recycled ones, have some kind of manufacturing impact. Logically, the less often you need to replace your roof, the lower the manufacturing impact. But the best advice I can give you is to talk with a professional and work together to decide what will be best for your specific set of needs. Look around your city and see who can advise you about locally appropriate choices. In Seattle, you could start with and the Environmental Home Center. Homeowners with rotting roofs in other parts of the world could also glean some useful information from these sites, as well as from the U.S. Green Building Council and the links on its web page. Follow the trail to a local or regional group that can begin to advise you.