101 Ideas: Consider an ecoroof

Instead of tar or asphalt, an ecoroof has a thin layer of soil and plants, says Greg Haines of Portland, Ore., who has been installing ecoroofs for several years. With a traditional roofing system, rainwater washes off rooftops and onto driving surfaces, eventually mixing with antifreeze and oil before it ends up in the sewer system. On an ecoroof, rainwater is absorbed into a vegetative roofing system, filtering out air pollutants and making cleaner water.

How an ecoroof works is simple. Rain falls on an ecoroof. The rainwater is absorbed through a layer of soil, then a layer of spongy material and carpet padding. The plants on the ecoroof grow, helping filter the air, providing habitat and food for wildlife and insulating the building structure underneath.

"The plants are up taking the water. It's evaporating naturally, and it's being returned to the natural hydrologic cycle rather than becoming a waste product that the sewage treatment plant has to deal with," says Haines.

When creating an ecoroof, it's essential to have a professional roofer brace or install a roof that can support the extra weight that an ecoroof creates. Consult a structural engineer to examine the existing roof structure. Once the structural support is in place, a bottom layer of a durable, waterproof, heavy-duty rubber liner is installed over the roof. A pond liner works.

Next, install a layer of spongy material, like carpet padding, over the roof liner. This material is lightweight and absorbent, helping keep moisture at the root level. To help retain moisture at the top of the roof where it is first to dry out, install an extra layer of carpet padding. Drench the padding with water. Make sure to have drainage holes at the edge of the roof to allow excess water to run off. Install a layer of netting over the padding to help plant roots grab onto something.

When just an inch of rain falls, the ecoroof should absorb most of the rainwater. In a heavier storm, the ecoroof softens the impact of the heavy volume of rain, and water runoff is lessened in comparison to a traditional roof.

One disadvantage to having an ecoroof is the expense of installation. However, ecoroofs last twice as long as a traditional roof and look better. Plus, ecoroofs help insulate structures, keeping them cool in the summer and warm in the winter.

(For thousands of other ideas visit www.hgtv.com. Distributed by Scripps Howard News Service.)

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