Green Roofs: An Aesthetic Upgrade That Can Lower Costs

From the stunning entrance within Boston’s Back Bay, the Four Seasons Hotel Boston, seems like just another luxury hotel. But there’s a lot more to this lavish high-rise than meets the eye. Visible from more than 50 rooms in the hotel—and from other high-rises throughout the city—is a lush, vegetative roof that provides aesthetic appeal and fresh vegetables for the hotel’s restaurant. 

The Four Seasons Hotel Boston is one of many facilities in the United States with vegetative roofs. More than 4.3 million square feet of green roofs were installed in North America in 2010, according to the Annual Green Roof Industry Survey. 

“The wonderful thing about the roof is that in addition to the many environmental benefits, It's also aesthetically pleasing to look at,” says Kristan Fletcher, director of public relations for Four Seasons Hotel Boston. 

With endless design possibilities, complex installations and long-term maintenance requirements, specifying a green roof for your facility can be a complex decision.  From hiring the right contractor to tailoring plants and features to meet the needs of your building, here’s the 411 on effectively implementing a functional, sustainable roof. 

Why it’s good to go green

The EPA cites key benefits to green roofing, including reductions in energy use, air pollution and greenhouse gas emissions, as well as improvements to human health and comfort. But for many facility managers, the key purposes of adding a green roof are to improve a facility’s insulation, reduce stormwater runoff and extend the leak-free life cycle of a building’s roof. 

“The investment is that water proofing won’t have to be replaced in 15 or 20 years,” says Geoff Arthur, a former project manager at Apex Green Roofs, Inc., a Somerville, Mass.-based design, build and maintenance firm that specializes in the green roof industry. “Green roofs will double the lifespan of your roof—that’s the ROI for facilities.”  According to the Apex Green Roofs website, green roof installations can improve insulation and reduce heat flow as much as 90 percent in a warm climate and 30 percent in cold climates.

Those aren’t the only reason green roofs are being installed. While it’s a popular trend right now because of their aesthetic appeal, many architects and builders are interested in installing green roofs to create more useable space, Arthur says. “Budgets are tight, so the prospect of increasing a facility’s value is often more attractive than the environmental and sustainable features,” he says. “And while it’s expensive to create an amenity space on the roof (installing walkways, railings, etc.), the additional usable space makes it worth it for the experience.” 

Preparing to install the roof

If you’re interested in creating a green roof, it’s important to develop project expectations before hiring a roofing contractor by clearly define your objectives and goals to ensure your green roof is designed and installed with an established ongoing maintenance program correctly to achieve optimal results, suggests Steve Koneval, executive vice president of Roth Brothers, Inc., a Sodexo Company that provides building services and construction nationally, and is headquartered in Youngstown, Ohio. Use the following three criteria to help establish the goals of the installation, Koneval suggests.

• Do you want to reduce stormwater run-off? If so, the type of vegetation as well as the layout of the system can achieve this goal.
• Do you want to reduce the urban heat island effect?  Having vegetation on the roof reduces the effects of conventional black rooftops that absorb and then re-radiate light from the sun as heat.
• Are aesthetics a priority? If so, then budget for benches, walkways and decorative lights. In addition, various types of vegetation can add architectural appeal. 

After answering these questions, look at the structural capacity of the building, and design a system based on how much weight the facility’s infrastructure can hold, Koneval says. “Green roofing is a niche market and although there are many reasons to install one, this type of system is not for everyone.,” Koneval cautions. “The worst mistake you can make with this type of roof system is to cut corners or not thoroughly research up front.”

Installing the roof

Just like any other job in your facility, it’s important to know the specific materials that go into installing a vegetative roof. “Make sure you don’t structural overload your building,” Koneval says. “Do your homework upfront to get materials that are easy to get in your geographic region, require minimal maintenance and are cost-effective.”

If your facility’s roof can support the extra weight of a green roof, Arthur breaks down the build process in four steps: 

1. Get a standard waterproofing element. You’ll need a membrane to prevent leaks.

2. Add a drainage layer to drain excess water from a storm or oversaturation. 

3. Then apply engineered growth medium. The custom-blended rocky soil can contains perlite or specially treated shale. It is professionally blended to hold a certain amount of water, making it easier to trap vegetation and keep plants healthy. It also gauges the maximum amount of weight the roof can hold at saturation. 

4. Add plants and vegetation. Consider the types of plants you want to incorporate in the roof, including planters, seeding, flowers, vegetables, features, etc.  

Maintenance considerations

Green roofs can incorporate other elements beyond planted material, such as patio designs or solar panels, but the more you add, the more extensive maintenance will become, Koneval says. “Native plants are generally low maintenance,” he says. “They can be miniature plants and still keep your objective of adding color, protecting your roof and reducing urban heat gain.”

Maintaining a green roof is more than just watering and weeding plants, as safe maintenance is key to reducing hazards for the building and the community. “Plants have to be kept up or they become a fire hazard,” says Ron Burton, independent contractor and former vice president of codes, standards and regulatory affairs for Building Owners and Managers Association International (BOMA). “Make sure to connect with local authorities and check your local regulations and inspection requirements.”

How to find the right contractor

It’s important for any facility manager to find the right contractor, especially when taking bids. “Relationship building starts at the budget phase,” Arthur says.  “Make sure you are getting responsible quotes, good estimates and any available LEED [Leadership in Energy and Environmental Design] credits from contractors with professional affiliation, a portfolio and lots of experience.”

Don’t be afraid to bring in contractors and designers at the initial brainstorming session before the project takes off. “The more opinions and background you get into the project early,” Arthur says, “the more responsible you’re going to be with your budget by avoiding surprises and change orders.”