Last spring was special for Karen Raschke and Don Creach. For the first time, purple flowers peeked over the eaves of their Richmond, Va., roof, greeting them as they pulled in their driveway. “It’s weird to want to come home and see how your roof is doing,” Raschke says, “but we had that sense of expectation and delight.”

Marcus de la fleur and Ben Rush know the feeling. Last year, they completed their own green roof atop a porch attached to the two-flat house that Rush owns and de la fleur rents in Elmhurst, Ill. “In and of itself, [the vegetated roof] isn’t going to change the world,” Rush says. “But we’ve managed to regreen something like a billionth of the square footage of Elmhurst.”

And that, say green roof advocates, is a start. Green roofs, also known as living roofs, are a multilayer system usually installed on flat or low-slope roofing. Capped by a vegetated cover that is often comprised of hardy, droughtresistant plants, they can last for 40 years — about twice that of traditional flat roofing.

For decades, houses in Germany and Japan have sprouted such roofs, but Americans are just beginning to take note. “It’s a nascent industry in the United States, but it’s growing quickly,” says Leslie Hoffman, executive director of Earth Pledge, an environmental organization that runs a green roof awareness program.

In America, cities are interested in green roofs for potential environmental benefits — combating pollution and the urban heat island effect as well as providing a way to address storm water run-off problems. Chicago was one of the first to embrace the trend, with Mayor Richard M. Daley installing a 20,000-square-foot green roof on top of City Hall in 2001.

Ed Snodgrass, who runs Emory Knoll Farms, the only green roof plant supplier in the United States, says the residential market is still tiny. “The demographic [of a green roof homeowner] would be a person who’s really concerned about their own little footprint.” And a person who can afford to do something about it. For the individual homeowner, a green roof can double or triple the cost of typical roofing.

But a green roof’s value is not about greenbacks, Snodgrass says. “People see an intrinsic value in that green space whether it’s from a sense of ecological responsibility or whether it’s the idea that ‘I don’t want to look at this roof any more. I’m going to put something more natural there.’”

For de la fleur, a landscape architect who works for the Conservation Design Forum, the group that designed Chicago City Hall’s green roof, one benefit was immediate. “[Our] porch finally became useable space,” he says. “Prior to that it was the hottest room in the summer and the coldest in the winter. We could only use it for storing things. Now we use it all year round.”