Green Roof 101

Washington, DC (July 31, 2008)- We’ve heard about green roofs, seen lots, and even trampled across a couple, but we really didn’t know too much about what makes ’em so great, so the other day we accompanied DC Greenworks executive director, Sara Loveland, on a tour of a few of DC’s eco friendly rooftops. We know green roofs help get LEED points, but wondered: What does the sparse vegetation actually do?

Sara shows us the modular green roof system DC Greenworks installed atop The Reeves Building on 14th St. She says the main thing green roofs do is reduce run-off. When it rains, storm runoff goes right into local sewers and water treatment systems. So when it really storms, the water floods those systems, causing overflow of raw sewage into the Potomac, Anacostia, and Chesapeake Bay watershed. With an extensive green roof, you hold the first inch of rainwater, which doesn’t sound like much, but can make a huge difference when it comes to reducing runoff. And the vegetation also acts as an insulator, lowering heating and air conditioning bills.
Next we swung by Taurus Development Group founder Gail Montplaisir’s condo at City Overlook on Belmont St. Gail tells us she’s been using green roofs since ’86 and couldn’t resist including them when she developed City Overlook two years ago. She says that ideally green roofs are self-sustaining with no help from a gardener or irrigation system; the vegetation should be able to thrive on rainwater alone. Two years ago, when they were first delivering condo units, she says green features were a nice plus. But now that Taurus’ 27-unit Lofts 11 project on 11th St. is coming online, she says sustainability has become a major factor in some purchases.
Finally, we made our way to 1353 U St. where we snapped Sara with Bognet Construction’s Bill Shake, helping do the build-out for Greenstep’s “510nm” mixed-use sustainable renovation of a 1920s building. Bill shows us the JDrain (which we thought looked like egg crate bed foam), which they lay down on the roof over a watertight membrane. The holes in the JDrain allow water to collect in the cells feeding the plants, and whatever water overflows collects on the membrane and drains off the roof.
We even climbed a ladder to get this “before shot” of the roof while the Bognet guys were hard at work. Sara tells us this project was a recipient of the District Department of the Environment Greenroof Pilot Subsidy Grant Program, earning the developer $3/SF towards the cost of the roof install. The next round of applications are due Sept 9 and Sara invites anyone interested to contact her directly.
The same shot a few days later once several tons of Rooflite soil (a special kind of dirt which minimizes roof load but is heavy enough not to blow away in the wind) was laid down over the JDrain. Sara tells us the actual plantings for the installation won’t take place until the fall when the weather is more moderate, but in the meantime, DC Greenworks is busy with what Sara says has been a “huge” increase in business in the last 18 months.
For the full article, visit Real Estate Bisnow- Green Roof 101.