Sunday, July 3, 2011

How to Create a "Green Roof"

A poster on the Cleveland Park Listserv wrote this very helpful account of how she and her husband installed a "green roof." If you'd like to learn more, you can start with The Green Roof Manual by Edmund C. Snodgrass and Linda McIntyre.

We put a vegetated, a/k/a, "green roof" on our sunroom a couple of years ago. Ours is a simple roof with just a shallow root area accessible via a window, not an elaborate elevator accessible one such as on the American Institute of Architects' building. We didn't have a big budget. Ours is somewhat sloped -- flat roofs are easier.

Our new green roof looks much nicer than our old roof. Imagine looking at sedums interspersed with drifts of iris, phlox, chives and other flowers in bloom; it is now an extension of our garden rather than a barren gravel patch. Plus, the roof will last longer since the surface is protected from the sunlight and weathering, a savings for us. In addition, the sunroom is cooler in the summer due primarily to transpiration of water from the plants, but also just from the insulation provided by the plant-shaded soil mix.

Not surprisingly, the room is warmer in the winter. It is "greener" because it absorbs and/or filters rainwater rather than contributing to storm water runoff, which is a big pollution concern. The DC Riversmart Homes Project offers grants to offset the cost of greening a roof as a means to encourage DC residents to invest in the upfront cost of a vegetated roof in the interest of longer lived roofs, reduced energy costs and less pollution.

Alex Rounds of Green Way Works did the roof for us. Call 240-338-7049 or 301-270-668. A structural engineer he knows advised us on the reinforcement we needed. We did the planting, and we are very pleased with the roof.

We also consulted with DC Greenworks, 202-518-6195, which does a lot of grant work with the DC RiverSmart Homes Program.

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