Ten years after Ford planted vegetation atop a massive truck assembly plant, the largest living roof in the U.S. is flourishing and others have followed the automaker’s lead.
Ford was a pioneer a decade ago when it created a living roof on top of the Dearborn Truck Plant. It was a unique way to save on roofing materials and cooling costs while addressing water runoff and other ecological concerns.
“Ford was incredibly courageous and forward thinking when they evaluated and moved forward with a green roof,” said Clayton Rush, manager of Xero Flor America in Durham, N.C., whose parent company in Germany worked with Ford on the project. “They became a well-recognized pioneer.”
The success of the Dearborn truck plant roof prompted Ford to do more. A year ago, when a 2,500-square-foot portion of Ford headquarters needed to be redone, the automaker turned a second time to water absorbing plants.
When Ford took the plunge, there were fewer than 50 living roofs in the U.S. Today there are about 10,000 and growing, Rush said, with numerous companies supplying them. They adorn everything from doghouses and homes to commercial, government academic buildings.
Grasses now grow on the Empire State building; Nintendo headquarters in Redmond, Wash.; a FedEx facility at Chicago O’Hare International Airport; and a 7-acre spread atop the Javits Convention Center in New York.
Don Russell worked in Ford’s environmental quality office in 2000 when he was given a unique assignment: Refine Bill Ford’s vision to reinvigorate the historic Rouge industrial complex by covering the roof with grasses instead of tar or shingles.
“I’m a chemical engineer, so it was far from my comfort zone,” Russell remembers. “I was told to evaluate what was out there commercially to do this roof.”
The assignment was more than ecological whimsy. Ford wanted to expand the facility, situated in marshland. There was a cost of about $50 million to meet new water quality regulations by reducing toxic storm water runoff from the plant site into the Rouge River.
Famed eco-architect William McDonough was tapped by Bill Ford to develop the master plan for plant expansion and installing a 10.4-acre roof of thirsty grasses and meadows over porous paving materials as a natural storm water management system at a cost of only $15 million. Ford spokesman Todd Nissen said studies show the roof has reduced runoff by 42 percent and contains 85 percent fewer suspended solids.
Russell’s research found it was not being done in the U.S., but Europeans had been doing it for 40 years. The truck plant roof could support 25 pounds per square foot, and Xero Flor of Germany had a lightweight vegetation that weighed only 11 pounds per square foot when saturated with water.
About 15 acres was turned into a farm to grow a collection of 11 grasses known as sedum, and in fall 2002 the sedum was installed on the roof, much like laying sod.
Rush said the Ford roof cost $8 to $15 a square foot to install and maintenance is 5 cents to 50 cents a square foot annually.
After Ford’s large-scale project, the idea gained popularity, Russell said. “The rest of my career was giving presentations and responding to mail about it,” he said. He retired in 2006.
Earlier this year, the 64-year-old was asked by the company that maintains Ford grounds to help look after the roof again. Russell checks it once a month.
The roof never needs mowing. It gets fertilized each spring and relies on rainwater, but there is a backup irrigation system that is used a couple times a year if there is a dry spell.
“It is 10 years old and has shown it can last,” Russell said. “We have never replaced anything.”
The original bird species have all survived, but four have become dominant, including killdeer and sandpipers, which are roof-dwelling birds.
“The only thing we didn’t plan for was the Canada geese,” Russell said. They come over in the spring and raise their young. The downside: goose poop on the paths between buildings and on the roof.
Rush said a living roof can last 35 to 70 years compared with conventional roofs that have to be replaced after 15 years, at a lot of cost and disruption. Vegetation keeps the roof, and the building it covers, cooler.
Xero Flor America expects demand for naturally covered industrial roofs will keep growing because of the long-term savings and the need for storm water management in cities.
Consumers tend to look more favorably on products from companies seen as environmental leaders, Rush said.