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 (Mich.) 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 it evaluated and moved forward with a green roof," says Clayton Rush, manager of Xero Flor America in Durham, N.C., whose parent company in Germany worked with Ford on the project. "It 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 the 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 that number is growing, Rush says. Numerous companies supply them, and they adorn everything from doghouses and homes to commercial, government and academic buildings.
Grasses now grow on the Empire State Building; Nintendo headquarters in Redmond; 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.
Bill Ford tapped famed eco-architect William McDonough to develop the master plan for plant expansion, and install 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 $15 million. Ford spokesman Todd Nissen says 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 says 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 says. "The rest of my career was [spent] giving presentations and responding to mail about it," he says. He retired in 2006.
Earlier this year, the 64-year-old was asked by the company that maintains the 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 says. "We have never replaced anything."