Solar Isn't the Only Way to Green Your Roof

One of the most striking things about the new California Academy of Sciences building in San Francisco is its roof. The 2.5-acre undulating span is planted with 1.7 million native plants. It's green, lush, and quite functional.

While they're still rare, living roofs are part of the much larger green movement in the U.S. They can improve air and water quality, help reduce cities' heat-island effect, they're durable, and can cost the same as a conventional roof, as well as can help preserve animal habitats and biodiversity.

And such green roofs aren't just for large commercial buildings.

Think of England, where almost half of nation's residential roofs are thatched or topped with layered straw, water reed, and other dry vegetation. It's an ancient practice that's suddenly cool and hip. While it's unlikely people in the U.S. will start thatching their roofs anytime soon, don't be surprised if you see smaller, less extravagant versions of the California Academy of Sciences' being installed near you.

Building a Truly Green Roof
So what is a green roof, really? They're "vegetated roof covers" that take the place of shingles or tiles.

There are two types of green roofs: extensive, which are low-maintenance and are generally planted with low-profile ground covers that traditionally do well in all kinds of weather, and intensive roofs, which are higher-maintenance, and resemble a park, with high-profile plants and architectural features such as ponds or waterfalls. The cost of installation may range from $9 a square foot to more than $40 a square foot. 

There are plenty of great reasons to consider planting a living roof--rather than covering it in metal, ceramic or standard asphalt tiles--when it's time to replace what you've got. One of the best motivations is that they can last twice as long as a conventional roof. You can grow herbs and other practical plants. They better insulate your home, saving in heating and cooling costs.

They're quiet. Forget about traffic or airplane noise.

And let's be honest here, a green roof's cool factor is very high. Your house would be a must-see attraction for everyone in town.

Sources
Green Roofs for Healthy Cities
GreenRoofs.com
Roofscapes

About the Author
Mary Butler is a Boulder, Colorado-based writer and editor, who spends much of her free time remodeling an old house.