The 5th largest green roof in the United States sits atop the Target Center arena in Minneapolis, MN.
Since mid-2009, Green Roofs for Healthy Cities (GRHC), a decade old non-profit association whose mission is to develop the green, or vegetated, roof and wall industry throughout North America, has offered its GRP Accreditation Program. To become certified applicants must pass an examination process that focuses on five key areas including: predesign, design, contract management, quality assurance and support, and maintenance. One of the many goals of the program is to provide the baseline training necessary to keep green roofs at their optimal performance level.
"Many green roof requests for proposals across the country are now requiring that an accredited Green Roof Professional be part of the team," said Steven Peck, President of Green Roofs for Healthy Cities, at a recent green infrastructure presentation in Minneapolis, MN. "Successful green roofs require a combination of knowledge and expertise in the so-called 'black arts' and 'green arts.'"
Peck described the black arts as focusing "on critical, non-living elements of a green roof assembly, such as waterproofing, structural engineering, and project management." The green arts, he explained, deal with living architectural components, such as water management, growing media, plants, and maintenance.
Green roofs account for an estimated 10 million square feet of the 4 billion square feet of flat roofing that is either built or replaced in North America each year (GHRC 2010). Amazingly, despite the severe economic downturn over 2008, the green roof industry grew by 16% in 2009 in North America. It is anticipated that green roofs will continue to grow by 2% annually and, because of this growth, many roofing contractors and design professionals are turning to the GRP designation for answers.
Rex Greenwald, Project Executive for Tecta America (Stock Roofing), recognizes the unique niche for the GRP Designation. "I'm a roofer but this is an ever-expanding and necessary market in our industry, so I needed to have an avenue to learn the other components of the green roof business," he said. Having the GRP designation helps differentiate Greenwald from others in the industry, providing him recognition with respect to the design, implementation, technology, and maintenance of green roofs.
"We wanted to develop a consensus around green roof design and installation," said GRHC's Peck. "We began developing the GRP occupational standard back in 2002 and now over 400 professionals have become GRPs since accreditation began in mid-2009."
"GRHC is by far the most recognizable and professional organization out there in regards to this up-and-coming green roof market and I want to be on the forefront," said Greenwald.
Individuals with GRP accreditation will be qualified to identify and form project teams, function as team leaders for the green roof system portion of a project, and maximize green roof system benefits. While it's impossible to know for sure, having a GRP as part of the team for the Aquascape green roof may have changed the design.
The location of the Aquascape facility's failure was primarily within the unheated parking garage's down-slope edge. At over 8%, the building slope directed nearly 6 acres of icy runoff onto this area. Without the benefits of plant evapotranspiration of water during the winter, a GRP may have identified the issues with seasonal weight loadings on the roof. A typical ballast roof system weighs between 5 and 10 pounds. The design of green roofs as an extensive (shallow soil profile 2"-6") or intensive (deep soil profile 6"+) can weigh an additional 20 to 70+ pounds per square foot when saturated. Along with many locations in the Midwest, Aquascape's headquarters had an unusual amount of snow this year; this anomaly, combined with the prolonged freeze and thaw cycle over the unheated parking garage, could have resulted in massive ice dams, weight stresses and ultimately failure.
