The Green Roof Tilted


Living walls turn the industry a full 90 degrees

The innovation behind green walls is turning the turf industry a full 90-degree angle. Nowhere is the trend in unusual turf more noticeable, thus far, than PNC Financial Services Group, Inc.’s “living wall” at Fifth and Woods in Pittsburgh, Pa. It is a 24-ton, 85-foot-high green wall system mounted on the south-facing wall, which was once granite. Completed a year ago, it is the largest media-based vertical garden of its kind in North America.

The PNC wall is a living wall of plants spanning 2,380 square feet. It is located on the south side of PNC’s headquarters, at the corner of Fifth Avenue and Wood Street.
Photos courtesy of George Irwin.

With careful maintenance, as its plants continue to grow, so does the business of Green Living Technologies (GLT) of Rochester, N.Y. GLT held the installation and maintenance contract for the first year, though its CEO and President George Irwin makes it clear, “We’re still ultimately responsible.”

In 1999, Irwin first looked to install a green roof. By 2003, he’d done that, and by 2004, he’d developed his first extreme sloped roof. As the angle of desire grew, it became the premise for his first living wall. Early on, he named his company Green Living Roofs. Now, GLT operates on seven continents with four manufacturing plants, and he’s installed green walls as far north as Nova Scotia and as far south as Chile.

PNC’s wall is just under 2,500 square feet, or roughly two tennis courts standing upright. Irwin promises his work will continue to get bigger and better. In fact, in November, he’ll unveil a 17,000-square-foot living wall in Chile in collaboration with Santigao partner Impacto Verde.

The PNC project

The wall went up in six weeks and was finished in August 2009, but it had to for PNC’s environmental focus to begin paying dividends in time for the G-20 Summit in Pittsburgh late last September.

Installed by Philly Green Wall, licensed architects since 1988 and a design-build company since the mid-90s, Michael Bucci of Philly Green Wall often works on GLT projects. Bucci assigned a six-man team, and PNC’s own construction crew did most of the back work.

Philly Green Wall installed the waterproof membrane, mounted the hardware (the aluminum bracketing and panel system-602 panels) directly on the wall’s reinforced concrete masonry, and then the trim, catch basins and finish work.

The key hardware component is GLT’s low-volume drip irrigation system. While standard components, they’re modified for a green wall application. There’s an irrigation line every 2 feet on center that emits 2/10 of a gallon of water per hour per square foot.

The system runs for approximately 15 minutes every other day, but timers stagger the flow on separate valves through nine zones, depending on moisture levels, which are monitored. “There’s more irrigation at the top of the wall,” Bucci says. Then gravity kicks in. “The system might run 20 minutes up top, but 10 minutes at the bottom,” Bucci says. “It’s assessed and adjustments can be made.”

Irrigation and fertilization are actually supplied through the same pump system, Irwin says, but it’s tricky because some areas are in full sun, and some in shade because of neighboring buildings.

“Going in we knew we would be challenged,” Irwin says. “But because of the marketing value [to his clients and to his own company], any of our walls has to be 110 percent right all the time. In the industry, everyone looks at us, at me. PNC came directly to us.”

The plant material

Everything revolves around the plant material, Irwin says. The first year is the most critical in regard to how the plant matter takes. Each project has its own microclimate.

Installing the low-volume drip irrigation system. Irrigation and fertilization are supplied through the same pump system, which is sometimes tricky since some of the wall is in full sun and some of it is in shade because of the neighboring buildings.

GLT’s manufactured bio-soil, which does not leach, helps. Irwin’s soil is highly nutritious, in fact it’s so rich that it can actually go without fertilization the entire first year.

He also creates a proprietary matrix of fibrous organic material, so the plants become well-rooted so they have to be cut out. “You can almost try pulling one out, but you would almost have to pull the wall down first,” says Irwin, a former 23-year landscaping contractor out of Cape May, N.J.

Bucci has done some replanting because some of the plants weren’t fulfilling the design in the PNC logo. With replanting, there’s a set method in place. Up on a man lift, which is how all the maintenance is done, workers will core out the individual plant’s soil with a bulb cutting tool, then pack in the new plant, which is then tied in to its sides with a light fishing line to help it root in. “It’s like it’s been stitched in,” Bucci says. “When it’s rooted, it’s pretty tight.”

An entire individual panel of these vertical canvases can come off the wall, if necessary. Some companies have seasonal walls that are replaced three times a year.

Plants are selected for color and hardiness for each geographical region. PNC’s colorful palette of plants include variegated carex, sedge grass, heuchera, ajuga or bugleweed and evergreen ferns. It makes for a sea of small red and green lettuce-like leaves.

PNC’s wavy design was created by Kari Elwell Katzander of Mingo Design in New York to represent a wave of change and an example of a public sector company doing something different. She’s designed seven living walls in New York. “Some plants did better than others [initially and the first year],” admits Irwin, who explains that’s not good enough for his internal specifications. He’s swapped out ferns for kewensis. “It’s not that the ferns failed,” Irwin says. “They were getting too much sun [so they browned out].”

Keys to maintenance

Among the keys to short and long-term success of the green living wall in Pittsburgh, or anywhere:

1. Checking the perimeter and the edging detail. “That always gives us an idea of what’s happening between,” Irwin says.

2. Evaluating the irrigation system weekly, checking for clogged emitters, adjusting zone valves, changing filters and making sure the catch basins are draining freely from the bottom.

3. Studying the plants, which are always an indicator of what’s going right or wrong. “You can see it right away,” Irwin says. “You can tell from the ground level.”

As this first year ends, the physical maintenance will transfer to Plantscape, Inc. in Pittsburgh, under the direction of Chuck Croskey. GLT then becomes a consultant on a weekly basis, if necessary.

Plantscape did not have any green wall experience when it took on this local contract, but Irwin says his company helps to educate and to predict future problems, and does sufficient on-site teaching.

Once a month, Plantscapes will be up for scheduled maintenance on a supersized man lift. They could also use a window-washing unit and work down. “And, just because it’s December, it doesn’t mean maintenance stops,” Irwin says.

GLT makes it a point to use local labor unions, always creating local jobs. When all is said and done, Irwin says a typical project of his will create 100 jobs and an investment in each community he serves. “It’s the perfect storm,” he says. “We’re satisfied that we’re using local general contractors and labor union, but we also have the plant people who know the plants that are going in. We’re able to combine both industries and keep everyone in the community working.”

The author has been published in national and regional magazines as well as daily and weekly alternative city newspapers. A gentleman farmer in Quakertown, Pa., he writes about people, social trends, historic preservation and 18th century America, agrarian culture, land use and sports and recreation topics.