Modern architecture emphasized freeform living spaces more than the masses surrounding the space. Walls grew thin and immaterial and seemed to slide by each other without touching. Flat roofs hovered, became as thin as possible, and tried to disappear. When cantilevered, the flat roof also emphasized horizontal space, another crucial aspect for modernist architects. Frank Lloyd Wright, whose work from the early 1900s greatly influenced Mies and the other Europeans, never adopted the flat roof as a signature—though some of his most famous houses, including Fallingwater, use flat roofs. But his typical low-slung, low-gabled roof was "was another means of achieving that horizontality," Brooks says.
Donald Olsen believes the stripped-down, flat-roofed forms of new types of architecture—factories, commercial buildings—also influenced modernist architects. There were practical reasons for adopting flat roofs as well. Corbusier, who saw his individual houses as reproducible, machine-like units that could be configured into apartment blocks, knew that couldn't be done with gabled roofs.
Corbusier also made use of flat roofs for freeform gardens and living areas—something that Olsen also provided for the roof of Peter Selz's house. "Corbusier knew that in France, land was scarce," says William Krisel, who designed many flat-roofed homes in Palm Springs and Los Angeles for the Alexander Construction Co. in the '50s and '60s. "So he put the garden on the roof, and the house didn't steal space from the garden. You ended up with more usable outdoor space than you started out with."
Krisel has another theory for the popularity of modern flat roofs—they made ideal outdoor bedrooms. "The weather [in California] was so nice, people liked to sleep outdoors," he says, noting that Rudolph Schindler, the European modernist who moved to Los Angeles in the 1920s, "was an outside sleeper." And Krisel notes that Richard Neutra designed flat roofs to serve as elevated viewing platforms, as at his Kaufmann house in Palm Springs.
And in the postwar years, Bay Area architects adopted the flat roof because it could be built with less material and much more cheaply than anything else, Brooks says. Brooks, who has designed flat-roofed houses but is better known for his unique pyramid-roof designs, recalls flat-roofed homes by such Bay Area pioneers as Fred and Lois Langhorst, Mario Corbett, and Brooks' former mentor, Roger Lee, who was known for designing elegant, low-cost houses for struggling intellectuals. "Roger Lee, a perfect flat-roof guy," Brooks says. "Economy."
But, as Olsen points out, few 'flat' roofs are absolutely flat. "Generally speaking," he says of his flat roofs, "I did what everybody else did. I introduced small slopes on the surface." If done properly, he notes, no one notices. "You simply had a small parapet, so if you look at the building, there was a straight line at the roof, and one was not aware of what was happening at the top."—Dave Weinstein
Photography: David Toerge, Michael Greene
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