When it came time to create a new science building for the Brooks School in North Andover, Massachusetts, there was no question that the building would be a sustainable facility. However, with every project, there is a budget and identifying innovative green features required going outside the box – or, in the Brooks School’s case, up to the roof.

“The green roof provided a range of benefits,” says Brian Palm, science department head at the Brooks School. “It’s one of the most visible green components available, and it’s something that can be seen and touched.”

By compiling a team with extensive green building experience and doing the appropriate
legwork up front, a green roof can become a wonderful addition to any school facility.

While green roofs have been identified as a signature feature of sustainable facilities, they also provide numerous “behind the scenes” benefits, Palm notes. These include storm water retention, reduced energy costs and providing a reinforced layer of insulation. For academic institutions, however, they also offer a teaching tool that can support numerous academic missions, from understanding the inner-workings of a living, breathing ecosystem, to a school’s efforts to become a LEEDcertified facility. Given the variety of options, it is important for schools to understand their reason for selecting a green roofing system and making sure their construction team – architect, engineer and construction manager – supports that mission.

Go Green or Go Home
At the Cambridge School of Weston (CSW) in Weston, Massachusetts, building a facility that would serve as a teaching tool for generations was the end goal of the Garthwaite Center for Science & Art. In addition to harnessing the school’s artistic abilities and scientific expertise in one building featuring art galleries and laboratories, the facility was designed and built to LEED Platinum standards. For CSW, the green roofing system enables the school to collect the maximum amount of sunlight while also creating a low-lying surface that catches storm water runoff and channels it through the plants to a natural splash bed running along the perimeter of the building. It compliments an already hands-on approach to learning, while also substantially reducing the school’s impact on the municipal water systems. Ultimately, while having such a facility enables the school to market itself as a leader in its commitment to sustainability, the Garthwaite Center is so much more than that – and therein lies the logic for highly visible components like the green roof.

“One of the primary goals in building the Garthwaite Center was to try and maintain as much of the natural world around us as we could in its design, and the green roof helps us accomplish that goal,” says Marilyn DelDonno, chair of the school’s science department.

The Brooks School’s Palm echoes that sentiment, noting that the green roof on the science building helps support multiple components of the school’s mission, while offering benefits tied to storm water management, greater heating and cooling efficiency and creating a natural habitat for students and faculty to nurture and grow. But perhaps most importantly, it emphasizes the importance of embracing green technologies.

“We’ve always been committed to supporting new ideas,” says Palm. “The green roof enables us to take a leadership role showing the benefits, and invite the community in to learn how we can improve our environment.”

Getting Your Team Planted
For both schools, it was necessary to seek out the resources with the proper background in sustainable design and construction to oversee the work. There are numerous questions to ask before moving forward on a green roof installation. To begin, schools should determine if their facility is strong enough to support the added weight associated with a green roof. At Brooks School and CSW, both facilities required additional steel reinforcement beams to ensure that the roof system could support the extra load.

Other factors to consider include the different types of vegetation to grow on the roof. This is of particular importance as most commercial green roof systems will not allow customized planting plans, requiring that customers stick to those species that the manufacturer has determined will work with a specific system. In addition, end-users need to determine up front whether they want an extensive or intensive roofing system, which will also impact the support structure for the roof. An extensive system typically has a growth media between 2 and 6 inches deep, with a maximum weight of approximately 35 lbs/sq. ft. when fully saturated. An intensive system has a higher saturated weight, ranging up to 200 lbs/sq. ft., with a growth media depth from 8 inches to 2 feet.

Schools should also consider the importance of energy modeling before embarking on a green roof installation. Energy modeling performs a comprehensive evaluation of a building’s energy usage and then identifies the best design possible to maximize potential energy benefits. In the case of a green roofing system, energy modeling can help schools make the most informed decision possible regarding an intensive or extensive system, optimal siting on the roof, and what the end-user can expect in the way of possible energy savings. Having the right architect on board can make energy modeling a seamless process that helps schools make the best use of their green roof.

Keeping a Checklist
While any building project requires a team, green roofs bring different players and responsibilities into the mix. Jeff Navin, project executive for Consigli Construction Company, Inc., in Milford, Massachusetts, noted that there are many steps to take that will help ensure as seamless of an installation as possible.

“You absolutely need all parties on the same page,” says Navin. “When you’re dealing with details such as ensuring the membrane is compatible with the extensive or intensive system, or making sure the plantings are consistent with the growth media, close coordination between the architect, owner, CM and
subcontractors is critical.”

Inspecting the work before completion is also a must, as any mistakes will require a costly removal process, not to mention the dollars lost when plants and soil have to be replaced. Additionally, any errors in installation could also result in the violation of the product warranty. At the Brooks School, project manager Richard Scopelliti came up with a creative solution for a possible roadblock when the school asked for their green roof to have a dedicated foot path in between rows of plantings. Initially, the team decided to use steel angles attached to the roof deck in order to support the stone pavers above, but careful review revealed that penetrating the TPO membrane to connect with the plywood below would void the warranty. A new design was created, and the team worked around the problem before any work took place. By adopting a unique cribbing system to support the paver installation, the team avoided membrane intrusion and potential warranty violations.

End-users need to determine up front whether they
want an extensive or intensive roofing system, which
will also impact the support structure for the roof.

In both cases, high levels of preparation created a wonderful end result that has helped the schools to enhance their environment, both with an innovative teaching tool and improved energy efficiency. By compiling a team with extensive green building experience and doing the appropriate legwork up front, a green roof can become a wonderful addition to any school facility.

Todd McCabe, LEED AP is a project executive with Consigli Construction Company, Inc. He can be reached at: 508.473.2580.