Guided by its Quaker values, the prestigious Sidwell Friends School is committed to practicing responsible environmental stewardship. Sidwell’s Middle School Building is the first K-12 school in the United States to earn a LEED Platinum rating and the first-ever LEED Platinum building constructed in Washington, D.C.
One of the school’s storm water management features is a living roof, which was initially planted in 2005.
Because the school’s curriculum is grounded in teaching students about the natural world and their relationship to it, the 7,853-square-foot green roof acts as a living laboratory; upper and middle school science teachers and students use the site for hands-on learning and research.
After the initial planting of the roof five years ago, however, the plants - while native to the region - unfortunately did not adapt well to the “non-native” conditions of this rooftop.
In 2009, Sidwell Friends School officials made the decision to re-green the roof of the Middle School. They commissioned Brooklyn, Md.-based Furbish Co. to redesign the vegetated system for more-reliable coverage using plant varieties more fitting for the non-irrigated, shallow profile and extreme rooftop conditions - namely, sedum varieties proven successful on extensive living roofs in the mid-Atlantic region.
In fall of 2009, Furbish Co. removed all of the soil from the existing roof and replaced it with a different media blend designed specifically to enhance plant growth and drainage within a rooftop environment. Furbish Co. fully replanted the Middle School roof in March 2010 with proven materials. Supplementing the workhorse sedum varieties, various accent plants - Schizachyrium scoparium, Allium cernuum, Aster ericoides, Aster oblongifolius “October Skies,” Echinaciea purpurea, Liatris spicata - were introduced to embrace diversity in the micro habitat and add visual appeal.
The plugs were hand-planted at one-foot centers, allowing room for growth. Furbish Co.’s planting crew also mounded up areas of deeper soil in high-interest locations to hold perennial accent plantings such as native grasses. “The most interesting part was that Furbish Company spread cuttings randomly across the soil to fill in gaps between plugs,” said Steve Sawyer, Sidwell Friends School plant manager. “These look like half-inch-long pieces of succulent plant leaves that are just lying on the surface. The cuttings will eventually root and help create a ‘green’ carpet.”
Furbish will return over a two-year period to ensure proper plant establishment and maintain the vegetated roof system - feeding, weeding and monitoring conditions for long-term viability. Successful maintenance is the result of anticipating problems and preventing their occurrence. The sooner plants are naturalized and fully covering the roof, the quicker maintenance protocols can be reduced.
Now that the roof has been replanted, the students are back outside taking notes on the issues surrounding water reuse and conservation and the urban heat island effect. As an unforeseen bonus, Sidwell Friends School was able to use the replanting of the roof as a teachable moment - an example of the lessons learned when experimenting with new approaches.
Sidebar: Just the FactsProject: Sidwell Friends School, Washington, D.C.
Vegetated Area: 7,853 square feet
Design/Install: Furbish Company LLC
Green Roof Plant Specialist: Ed Snodgrass, Emory Knoll Farms
Client: Steve Sawyer, Sidwell Friends School
Perforated Aluminum Edging: Resource Conservation Technologies
Ballast Stone: Skyland USA
Rooflite Extensive Growth Media: Skyland USA
Rooflite Drainage Media: Skyland USA
Sedum Plugs and Cuttings: Emory Knoll Farms