The Garden Upstairs

Lee Skabelund stood in the midst of his creation, contemplating its every aspect without moving from where he stood. It’s not often that a designer can enjoy such complete perspective over a finished project.

That the creation is only 15 feet by 20 helps. This experimental green roof, or living roof, has been installed over a third-floor breezeway in Seaton Hall’s west wing. Black plastic irrigation lines contrast with green rows of native plants and the reddish soil substitute that overlies layers of root barrier and waterproofing. New copper flashing, left over from a project elsewhere on the Kansas State University campus, reflects the morning sun, and an anemometer spins in the breeze.

That instrument and a bundle of coaxial cables hint at how closely monitored this fledging garden will be. Fluttering pink surveyor’s flags mark temperature sensors, which every five minutes send a fresh set of readings from various soil depths to the on-site recording station.

“This one is probably in the worst shape,” Skabelund said, examining an inch-high purple prairie clover with a clinician’s care. “Probably due to predation by birds. But it’s starting to bounce back.”

This high-wire gardening act won’t provide heirloom tomatoes or cut flowers. Instead, it aims to assess how such a roof can reduce the urban heat load and control runoff from the region’s intense thunderstorms.

The design mixes 14 grasses and forbs native to Kansas inside a border of sedum, a shallow-rooted succulent. Even at its deepest point, the roof offers only about 6 inches of growing medium, so a big question for the experiment is simply about plant survival. After two growing seasons, the irrigation will be removed and the 200-plus plants will have to make their own way.

This is the first such living roof in the Flint Hills since settlers left behind the sod house, said Skabelund, an assistant professor of landscape architecture at K-State. Larger variations on the theme have been installed in settings as diverse as Seattle’s city hall and Salt Lake City, where a 70,000-square-foot meadow covers a conference center. But they’re still uncommon, and because most are flat they remain invisible to pedestrians.

A conventional roof, whether a rolled commercial type or a residential installation of three-tab shingles, has two big weak spots: It soaks up heat, which raises summer cooling costs, and it sheds water too quickly.

Isn’t shedding water exactly the point of a roof? Yes, but rain water gushing from every downspout has an unfortunate side effect of washing contaminants, from gas spills to dog poop, right into the town’s waterways. “Such storm surges also cause erosion, sedimentation and habitat loss for species that depend on those waterways,” said R. Todd Gabbard, assistant professor of architecture, who joined Skabelund on the project. “Green roofs, ideally, will slow building runoff to a long-lasting trickle rather than a short-term deluge, mimicking natural hydrology.”

All very appealing, but data is lacking, Skabelund said, particularly in the Flint Hills eco-region.

“There is a higher design cost, and higher materials cost,” he said. “It’s been said that green roofs can last twice as long as a conventional roof. But except in Europe, not many green roofs have been in place for very long.

“We know that living roofs work,” he said. “But what are the actual life-cycle costs? And can plants survive without being irrigated year after year?”

The possibility of answering these questions prompted Kansas WaterLINK, which funds research into improving the state’s streams and groundwater, to award a minigrant. But it took many hands and heads to make this roof a reality, Skabelund said.

For one thing, K-State Facilities understandably wants to know what’s happening on any university roof, however small.

“Bob Williams was very supportive from the beginning,” Skabelund said of the physical plant supervisor. And Abe Fattaey, interim director of facility planning, gave the go-ahead once funding was in place and he’d seen design drawings by architecture students Michael Knapp of Prairie Village and Mark Neibling of Derby.

They were among more than 30 students who participated from eight disciplines, from horticulture to biological and agricultural engineering, going back to fall of 2007. During that semester, Skabelund charged his specialized landscape architecture studio with conceptualizing green roofs for buildings across campus.

In spring 2008, students in the natural resources and environmental science capstone projects focused their proposals on three small green roofs atop Seaton’s west wing.

“That helped faculty members and Facilities staff think through the budget and other requirements for creating the first green roof on campus,” Skabelund said.

As the donations of materials show, this is not futuristic technology. The waterproofing (from Derbigum) is used across campus. Chicago-based American Hydrotech, which donated lightweight soil substitute and filter fabric, developed its “garden roof” business as an outgrowth of its traditional membrane roofing.

The roofing labor, donated by Danker Roofing as well as Facilities staff, relies on time-tested skills and principles.  Many of the plant varieties, from Kaw River Restoration Nursery, have been growing in the Flint Hills for centuries. And the garden border was made from a load of muddy gravel.

“We washed it all by hand,” Skabelund said, “with a hose and an old screen and some five-gallon buckets.”

Students from agronomy and biological and agricultural engineering made the planting and irrigation installation go quickly. And without state climatologist Mary Knapp and Stacy Hutchinson, an associate professor of bio and ag engineering, “monitoring would not be happening,” Skabelund said.

From this third-floor roof, the view takes in Seaton Hall’s many other roofs, and those across campus and the surrounding town. It’s a lot of asphalt shimmering under the summer sun at 11 a.m., but Skabelund and Gabbard resist declaring a roofing revolution.

 “Green roofs do have the potential to cool buildings, but are not the only option,” Gabbard said. “‘Cool roofs’ - light-colored, reflective roof materials - work well and are less expensive. The data we obtain here will be a good indication of the contribution green roofs can make.”

Skabelund concurs. “If we can have multiuse roofs that reduce stormwater, that reduce the urban heat load and increase oxygen production and biodiversity, then certainly it’s our duty to examine such potential.”

To that end, Skabelund and Gabbard are seeking funding and donations to convert the two small neighboring roofs, two stories below this one, to living status. Not a revolution, maybe, but something like an oasis.

Watch a clip from TV Channel 49 in Topeka

Here’s what the K-State Library staff think about the green roof.

For more information, contact:
Lee Skabelund, 785.532.2431
Todd Gabbard, 785.532.1129
Diane Potts, 785.532.1090