Let It Be: This Fan roof is planted with low-maintenance plants that reseed themselves. “At first … I tried to control them by weeding and plucking. Now I like to let it grow naturally,” Miller says. (Photo by Beth Furgurson)
The Benefits of a Green Roof
Whether it is part of a new home or added to existing construction, a green roof is not for the financially faint of heart. At two to three times the cost of a conventional roof, the investment is offset by solid benefits, especially if you are motivated by environmental stewardship. “A vegetative roof is an ecosystem that creates food and habitat for native birds and pollinators,” explains Patrick Farley, owner of Watershed, a local architectural firm specializing in ecological design. “The plants also help improve water quality by filtering rainwater and diverting storm runoff.” And, when vegetation absorbs carbon dioxide, releases oxygen and traps particulate matter, air quality is impacted as well.
Scott Birch of International Roofing has been putting green roofs on commercial and residential spaces in Richmond and Williamsburg since 2005. “Because it provides shade, insulation and evaporative cooling, adding green space to a roof can help reduce HVAC costs over time,” he says. “The vegetation extends the life expectancy of the roof by shielding it from UV rays, wind and temperature fluctuation.”
Susan Miller’s favorite place to stargaze is her rooftop garden high above the Fan where she can look down on the treetops below. Her green roof is a part of the LEED Gold-certified house that she and her husband, Kenneth Kendler, christened Phoenix Rising when it was resurrected in 2010 following a fire. The roof is a hybrid: part green roof, part roof garden, and includes a bat house and bird feeders. Designer Scotty Guinn Dilworth installed sedum mats for color year-round and planted two berms with native grasses as well as flowering perennials to support pollinators. “The plants take care of themselves,” says Miller, who simply scatters sedum cuttings to fill in bald spots. “At first, when they re-seeded themselves at random I tried to control them by weeding and plucking. Now I like to let it to grow naturally,” she says.
Green Roof Construction
“A green roof is built up in layers of waterproofing membrane, root barrier, drainage material, filter fabric, erosion blanket and insulation, explains Birch. “Combined, it can add up to 30 pounds or more per square foot.” It’s all topped off with growing medium — a mineral-based mix with low organic content engineered to support native plants but discourage weeds.
Scotty Guinn Dilworth, who specializes in sustainable garden design and installation, explains there are two types of green roof construction. “An extensive roof has less than 6 inches of growing medium, which limits plant options but is less expensive,” she says. “Intensive roofs have more than 6 inches of growing medium and will accommodate plantings similar to ground-level landscaping.”
“The plants themselves can be installed in several different ways,” says Birch. “Integral roofs are assembled on-site. We spread loose growing medium and then plant immature plugs of vegetation that will fill in after several months. Or, vegetation can be rolled out like sod in thick blankets of established plants.” Finally, Dilworth describes trays that are pre-planted modular “beds” of live plants which she assembles like tiles and locks in place to form a finished rooftop garden.
Trailblazer: This green roof was one of the first residential green roofs in Richmond. At 5,200 square feet, it is also one of the largest. (Photo by Beth Furgurson)
A Meadow Above
In 2004, when hurricane Isabel brought a massive oak tree down on the aging tar-and-gravel roof of their Midcentury modern home, owners Karen Raschke and Don Creech took advantage of the opportunity to add a vegetative roof. Theirs is one of the first residential green roofs in Richmond, and at over 5,200 square feet, the largest. The roof is planted primarily in sedum, a meandering carpet in shades of green that rolls over the sloping transitions from one roof level to the next. It has naturalized over the years as the plants have spread and today looks like a verdant meadow framed by the pavers along the perimeter that serve as a firebreak. And because there are no permanent steps (the roof is accessed by ladder for periodic maintenance) the building code doesn’t require guardrails. The roof is visually integrated with the surrounding landscape, making it a green roof in the most classic sense.
Plants that thrive in the harsh environment of a roof are typically sedum, succulents or native grasses that have adapted to the local environment, are easy to establish, and grow slowly with a low, spreading habit. They are available in a wide variety of leaf shapes, colors and textures and different species can be selected to bloom and go dormant at different times for year-round appeal. Some green roofs feature a spontaneous mixture of plant pairings that mirror nature’s style, resembling drifts of bright confetti. Others are designed as bold blocks of pattern and color.
Herbaceous annuals, edibles such as herbs and vegetables, and even shrubs and trees (planted in pots) are often added to conventional green roofs.
When you include pavers to support foot traffic, raised beds for variety, and furniture for relaxing or entertaining, a green roof becomes a roof garden.
Cascade of Greenery
John Duke planted a practice green roof on the overhang above the basement door of the log cabin that he and his wife, Darien, were renovating. It worked, and now the 100-year-old former hunting lodge in Bon Air has four green roofs. Their home office has a green roof, the balcony off of the office is a green roof and the office overlooks a green roof below. A cascade of sedum, native grasses and wildflowers seems to spill from level to level, ending in a pool of plants on the ground that were sprouted from sedum clippings. “It’s a different way of looking at a garden,” he says, “making something beautiful out of a necessity.”