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Up on a housetop, green, green, green
Thursday, November 23, 2000 By Tom Gibb, Post-Gazette Staff Writer
So, winter skulks in, and Northern Hemispherians hole up in living rooms, groping for solace by pondering such springtime issues as, say, what to plant on the roof this year.
A little buffalo grass, perchance? Wild onions? How about some sedum surprise?
Academician David Beattie and business executive John Maravich might be a few steps ahead of the pack on this one. They've been pondering how to make it easier and better to do away with shingles and cover the roof in vegetation instead.
Beattie is an associate professor of ornamental horticulture at Penn State University. Maravich is business development manager for JSP International, a Pennsylvania company with a Butler-area plant. And if one idea they've discussed works out, roofers might be making house calls, toting big sheets of roofing material bearing live, growing plants -- sort of vegetative roofs to go.
Which, of course, begs the question: Are Beattie and Maravich men with way too much time on their hands?
Not according to kindred thinkers.
"I like the aesthetics and I like the environmental factor," said Kin, a purchasing manager in his family business. "Part of what I like is that it makes a statement to the people who see it."
"Frank Lloyd Wright would have loved it," Beattie said of green roofs. "He might have thought it was great for Fallingwater. He wanted to bring the outside inside. He might say, 'What an idea!' "
America is land of the free and home of people whose concept of rooftop greening doesn't stretch much beyond moss in the gutters.
But a handful of American enthusiasts have lifted the idea from Europe and Asia and are cloaking roofs in vegetation, laying down a waterproof undercoating and topping it all off, usually with varieties of simple, durable plants -- often sedums, perennial grasses, "rock garden plants," Beattie explained for the horticulturally bereft.
It's not an oddball notion, either, proponents say.
Greened roofs last longer than their flat, tar paper counterparts, advocates say.
Studies show they're cooler, make the buildings underneath easier to cool and become sort of an oasis when summer turns cities into heat islands.
They breathe oxygen into the carbon dioxide of urban congestion.
And they handle water runoff that normally taxes storm-water systems, according to European studies.
"Do I see everybody putting a green roof on their building? Not now, not yet," said Robert Berghage, an associate professor of ornamental horticulture at Penn State University and Beattie's fellow researcher in figuring out how the whole process can be tweaked for the better. "Do I see more of these happening? Yes."
"Look out your window at this vast expanse of crummy-looking roofs, with their air conditioning units and asphalt. Then, close your eyes and imagine green, a rock garden," said Beattie, who studies the green roofs of Europe and waxes optimistic about someday seeing green in places like Pittsburgh's skyline.
Making green work
Enter JSP
The company's domestic headquarters is in suburban Philadelphia. But at JSP's plant on Route 422 just outside Butler, about 250 workers turn out something called expanded polypropylene, stuff that feels like Styrofoam but looks like burned macaroni stuck together.
Most people have never actually seen it, but they're around it every day.
It's an impact absorbent that auto makers fit around car bumpers, under the vehicle's skin.
But JSP, trying to expand the business, set out looking for other uses, too. On the journey, they bumped into Beattie, who filled one of Penn State's roles, offering technical assistance to commonwealth employers.
"We're an idea factory," he said.
Rule No. 1 for green roofs is that they have to be lightweight. The idea is to cover the roof, not collapse it.
Some of the secret in reducing mass lies in picking simple vegetation. "You're looking simply for a green roof, not a green garden," Beattie said.
Some of it has to do with what that vegetation is planted in. JSP came up a more porous formulation of expanded polypropylene, a version through which water can flow.
"When you ship it, you're mostly shipping air," Maravich said.
It weighs about 5 pounds a cubic foot, compared to 100 pounds for a cubic foot of soil.
It's also durable, a point Beattie makes by dropping an exercise mat-size sheet on the floor and strolling back and forth across it.
So, Berghage and Beattie decided they could poke holes in the sheets, plug in sedums and fescues and -- voila! -- have the top layer of a green roof, ready to be set down on a clay base and nourished with fertilizer.
Beattie figures the sheets could be shipped with the plants already plugged in place.
"We're hoping to take our package and go to people in the roofing business," Maravich said.
For now, Beattie and Berghage are massaging the concept, monitoring boxes of sedums planted outdoors, seeing what grows well, heading into the winter cycle in their first year of experimentation. Next year, they're hoping to test it on a larger scale by building their own green roof, 70 feet square, atop a Penn State root cellar.
"It's not a market that will grow next week," Maravich said.
But in the longer run, there could be green cash in all those green roofs, he guesses.
The selling points
Roof greening has become almost commonplace in Europe during the past 15 years, driven in part because a crowded continent will get its green spaces where it can.
"The Europeans face these issues before we do because we're a land-rich society with all the natural resources," Beattie said. "But we're screwing up our environment at a rapid rate, and at some point, we have to say we're going to do something about it -- whether it's solar panels or wind power or green roofs. They're all interconnected."
Swiss cities mandate that new buildings don green roofs to make up for the vegetation they destroy. For 15 years, Germany has planted green roofs -- Dachbegrunung, they call them -- anywhere from industrial plants to mailbox tops.
"In Germany, you go into their version of Home Depot, and you can go right to the green roof section," said Charlie Miller, owner of Philadelphia-based Roofscapes Inc., a company specializing in green roofs.
But proponents say that in the United States, greening roofs are still too technical to be a do-it-yourself project.
For the most part, high-profile buyers have been the owners of commercial and government buildings. "You're not going to sell it to John Q. Public," Beattie said. "You're going to sell it to John Q. CEO."
Among the selling points:
So, just how much does all this greenery cost?
Estimates run as low as 33 percent more than a conventional roof. Carl Kuhn -- whose Soprema Inc. in Wadsworth, Ohio, 15 miles west of Akron, offers customers greening amid a menu of 60 other roofing products -- figures he can vegetate a rooftop for $8 to $12 a square foot but do a conventional roof at as little as $3 to $6 a square foot. Miller estimates a premium green roof is twice as expensive as its conventional counterpart.
But the trade is still too new to really figure if a live roof can pay for itself, Berghage said.
"I suspect it would be a wash," he said.
A key, Berghage said, is greening a roof with low-upkeep vegetation.
"You may have to go mow the roof a couple times in the summer. You want to look nice for the neighbors," he said. "But my thinking is that the lower the maintenance, the more care-free it is, the more clients will buy it."
Besides, isn't the work of roof-top mowing a high-hazard occupation?
"If you think about it," Beattie said, "is it any more dangerous than sending the air conditioning man up?"
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Atop Chicago's 90-year-old city hall, workers are putting the last of 20,000 square feet of vegetation in place -- a green roof, advocates call it -- and touting it as environmental kindness in a steaming, smoking cityscape.