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So many great things found their footing in Chicago, Illinois. Yet when the history of the Windy City is written, all may be forgotten in comparison with the most important landscape architecture innovation in recent memory: green roofs. There are now more than 350 of them in the city on the shores of Lake Michigan.
Chicago may be the national epicenter, but there is huge opportunity in the green roof business all over the country. Alex Fransen, president of Steele Blades Lawn & Landscape, based in Louisville, Kentucky, runs a full-service landscape contracting company and reports that “green roof installation work falls in our lap every day. We don’t advertise that we do it. It just comes. Nobody else in our region is doing it. Work leads to more work. Even manufacturers’ representatives know to call us. There is no competition.”
Green roofs have to be sold, designed, installed, and maintained. That’s where the money is. Get up to speed on green roof technology and you can potentially be the Steele Blades of your region. If you don’t, you’re leaving money on the table for one of your competitors.
Don’t be daunted just because green roofs may be new to you. There was a time when no landscape contractor did irrigation installation—no less maintenance—or snow removal and de-icing. Contractors never used to think that they could put in ponds or do hardscaping. You have probably added services as your own business has endured. Green roof installation and maintenance may seem exotic now, but so did all those other new services before you added them to your repertoire.
If you’re in the green roof business already, you know how great the opportunities are. If you’re a newbie, the first step is to educate yourself. A great place for landscape contractors like yourself to start is the organization “Green Roofs for Healthy Cities,” which accredits green roof professionals, and runs a Living Architecture Academy that can teach you about the nuts and bolts of green roof installation and maintenance.
Once educated, your next job is to convince commercial and even residential customers to make their roofs come alive. There are a slew of great talking points, any one of which could make the sale for you.
The best place to start is with your potential customer’s wallet. Green roofs make dollars and sense. An economic evaluation by three Michigan State University engineers and economists revealed that green roofs have enormous back-end savings in heating costs, air conditioning bills, roof life, and the like, which will more than recoup your customer’s investment. The financial gain far outpaces the financial pain. An added plus is being eco-friendly and environmentally compliant.
Green roofs last longer than conventional roofs, says Tacoma, Washington roofing contractor and green roof installer Troy Wagner. Wagner believes that the green layer protects the roof membrane from UV rays and weather damage. “I’ve owned a roofing company for 18 years.
After looking at 25,000 roofs here in the Pacific Northwest, I can tell you that roofs that grew moss on them stopped aging.”
“Water isn’t what’s harmful to roofs,” Wagner argues. “It’s the ultraviolet rays from the sun. You can literally do a roof with treated tar paper as long as that paper is covered completely so that the sun can’t attack it.”
While money is always a good place to begin, other potential customers will respond best to an environmental argument. Green roofs fight global warming. A roof with plant life scrubs the air; a conventional roof can’t. Studies show that the surface temperature of a green roof can be as much as 90 degrees below that of a conventional roof. Because of evaportranspiration, the temperature of the soil material can actually be lower than that of the surrounding air.
You may find that that a particular customer sparks to the aesthetics. Green roofs look good; they can provide a fine local spot for contemplation and relaxation. Designated seating areas and walkways amid and amongst the planted areas can enhance the experience of the visitor.
Care should be taken if the green roof is going to be used as an amenity space, says Mark Fusco, a green roof consultant and eastern regional sales manager with Bison Innovative Products in Denver, Colorado. “If people are going to be walking around up there, enjoying the greenery, you want to protect the roof membrane and provide a walkable surface.” Bison makes modular pavers and tiles designed for green roofs.
In certain geographic areas like the parched Southwest, you can make a powerful stormwater management argument. On regular roofs, rain simply splashes down, gets funneled to drains, and then flows into sewers. Green roofs change all that. Professor Steven Cohan, who teaches in the plant science and landscape architecture department at the University of Maryland in College Park, Maryland, says that a well-designed green roof can retain up to 60 percent of a rainfall. With a green roof, your plant material and growing medium slows runoff and filters out pollutants.
Any one of the arguments laid out above could make the sale for you, but once you’ve sold the project, the green roof needs to be installed.
The biggest initial issue will be the additional weight that will be added. While the intricacies of roof load limits, lumber sizes, support braces, beams and the like are beyond the scope of this story, suffice to say that a man-made plot on a roof is not the same as an Almighty-made plot on the ground.
Earth-level planting can support just about anything, including a fullgrown oak brought in by crane. Rooftop gardens, not so much. Know the permissible persquare-foot load at every point on the roof that will support additional weight. Cohan says most commercial structures can handle 100 pounds per square foot.
Then, work with your customer to determine what kind of green roof to install. There are two principal types: extensive green roofs, and intensive green roofs. They’re distinguished first by the weight and stress they put on the roof, and second, by their plant material.
Extensive green roofs tend to have lower weight loads—the combined weight of framework, soil composite, and plant material. Weight loads fall into the 15 to 50 pound-per-square-foot range. The best plant material for extensive roofs are hardy varieties that require minimum maintenance and water, like those in the sedum, alliums, sempervivums, and delospermas families. Extensive green roofs can be lightweight. Moss roofs may require as little as two inches of a soil medium and put less stress on the roof than a decent snowfall.
Intensive green roofs bear greater weight loads—up to 150 pounds per square foot. They offer the opportunity for great creativity in your choices of plant material. Some green roofs even include trees and shrubs. Irrigation, maintenance, and climate will be some of the major variables here.
Intensive or extensive, the basic configuration for a green roof is the same, says Cohan. There’s structural support below the roof level. Above that is the roofing membrane. Above the roofing membrane is a root barrier that protects the roofing membrane and stops roots from penetrating it. Beyond that will be the insulation, then a layer of landscape fabric, and then a mostly-inorganic growing medium with strong water-retention qualities. Finally, there’s the vegetation.
An attractive option for new green roofs may be modular installations. Available from such companies as Weston Solutions in West Chester, Pennsylvania, LiveRoof in Spring Lake, Michigan, Firestone Building Products in Indianapolis, Indiana, and American Hydrotech in Chicago, Illinois, modular green roofs arrive in rectangular grid modules, often with vegetation already fully grown. You simply transport the interlocking modules up to the roof—they may even be sufficiently lightweight to be carried by hand—and lay them in place.
Modules vary in size, composition, weight, vegetation, growing medium, and more. They offer green-fromthe-get-go convenience and easy portability even after installation, in case the owner needs access to the underlying roof membrane.
“I’ve installed modular systems of all kinds,” says Steele Blades’ Fransen. “They work fine for all kinds of projects, including multifamily residential projects.”
Andy Subrock, who runs Southeast Green Roofs in Fairview, Tennessee, is both a licensed LiveRoof installer and a grower. “The beauty of the modular system is its efficiency,” Subrock explains. “We ship the modules with the plant material fully grown; every project is custom-grown, since local conditions will dictate what kind of plant material is used.”
Finally, don’t overlook permitting or utilities. Depending on your location, a green roof installation may or may not require the same permitting process as other structural renovations. Know your local zoning and building codes, or consult with someone who does. As part of your pre-installation analysis, take note of electrical resources and water supply.
When all is said and done and the green roof has been installed, whether modular or constructed, intensive or extensive, green roofs don’t take care of themselves. Even if you didn’t install a particular green roof, it doesn’t mean you can’t maintain it. Maintaining green roofs could be a great additional revenue stream for landscape contractors.
Debris needs to be removed. Weeding has to be done. Some patches may have died off and require replanting. Fertilizer may need to be applied. Rooftop irrigation may need to be repaired. Even extensive green roofs ought to be visited twice a year by a landscape professional.
To be fair, green roofs are not without their problems. Critics point to the possibilities of fires spreading easily on roofs that have gone tinder-dry, gusty updrafts blowing debris or pebbles onto streets or people below, and especially to potential rooftop damage from a faulty or overly ambitious installation. Fransen has also seen problems with inadequate aeration and poorly designed drainage. As he says, “Many plants, particularly the sedums, don’t like wet feet. It doesn’t matter if the plant is in the ground or on a roof.”
The benefits of a green roof can be remarkable for both the consumer and society. A year 2000 estimate posited that if every Chicago roof were made green, the city would cut electricity demand by more than the production of a typical nuclear power plant, and save an annual $100 million in energy costs. Best of all, someone needs to install and maintain them.
That’s a lot of green changing hands. Add green roofing to your array of services, and some of it will find its way to your pocket.