IN 1980s SAGAPONACK, a village in the Hamptons, new houses were awash in shingles and classical columns, to the dismay of the architect Fred Stelle.
“It was raging postmodernism,” he said, still sounding bewildered. He took modest architectural jobs expanding old houses with contemporary extensions and bided his time. Finally in 2001, he said, a Manhattan creative director requested a fully modern 2,500-square-foot new house.
Then came one client after another. Some are famous like Calvin Klein, Aerin Lauder and Michael Kors, sprinkling stardust on a firm that is housed in a converted potato barn in Bridgehampton.
As the business expanded, Mr. Stelle added three partners, Viola Rouhani, Michael Lomont and Eleanor Donnelly. Their firm, Stelle Lomont Rouhani Architects, quietly became known for a brand of beach modernism that sits lightly in nature, with million-dollar water views of sea grass and open skies.
This East Hampton home overlooking the Three Mile Harbor is one of the creations by Stelle Lomont Rouhani Architects.
This place to relax in solitude sits near one of the houses designed by Stelle Lomont Rouhani Architects.
The houses grew, along with the business. “Sometimes they got big,” said Mr. Stelle, 77, recalling one with 30,000 square feet.
Up and down the Eastern Seaboard, where the pleasures of a sunny day can dissolve into a roiling superstorm in the course of an afternoon, a confluence of laws and constraints point away from traditional architecture. Flood maps from the Federal Emergency Management Agency dictate construction, low-lying structures must sit atop steel posts to let rushing water surge safely underneath, and local height restrictions leave scant room for an attic, let alone a sloped roof.
A FLAT ROOF maximizes living space below and can host a 13-kilowatt solar array, planters thick with sedum or a mahogany sun deck. Atop a 4,900-square-foot house on Mecox Bay — with interiors by the designer Shawn Henderson — the partners gave a Manhattan real estate executive and his wife all three.
ON A SPIT OF LAND between the ocean and a pond, gossamer floor-to-ceiling white curtains by the interior designer Julie Hillman billow at open Fleetwood sliding doors, in high-performance glass crystalline rather than tinted “like very dark sunglasses,” Mr. Lomont, 58, said.
“MY HOUSES ARE ALL GLASS, WITH WATER VISTAS TO FEED YOUR SOUL,” said Deborra-Lee Furness Jackman, the Australian actress.
She worked with the firm for more than six years to completely replace an unremarkable two-story tear-down in the East Hampton woods. She also acquired and remade a modest midcentury house next door. That house is now stained black, its lot folded into her waterfront compound.
She requested cozy elegance, whimsy, and the feeling of a museum gallery in tune with her artistic aspirations. “I walk into any space, and I start creating,” she said. Her estranged husband, Hugh Jackman, attended the design meetings, but “this was my passion piece,” she said.
Ms. Furness Jackman admits that she is not good at compromise, but she listened whenever the architects and the designers said “That won’t work.” An early version of the layout had two stories, but one day Mr. Stelle lopped off the top to produce an unexpectedly elegant single-story pavilion at ground level, above a tall walkout basement with a screening room, an art studio and the garage.
Ms. Rouhani, 54, said she developed the plan “to incorporate this idea of drama” casual enough for family life.
A visitor might nominate the 15-foot asymmetrical pedestal dining table that Ms. Donnelly modeled to scale in Plasticine, and then carved full-size in blue foam.
After 18 months of development, the massive bleached walnut table, with a steel interior structure reinforcing its 11-foot cantilever, arrived by crane at one end of the sprawling great room, on the main level, and got welded into the floor beams. “Design is my passion,” Ms. Furness Jackman said, and “cantilever is my favorite word.”
AT A PROPERTY IN WATER MILL, Ms. Rouhani started from scratch and fortified a new design with disastrous weather in mind. Concerned that a beach cottage that once belonged to Christie Brinkley would not survive another storm like Hurricane Sandy, the architects shifted the replacement house back from the ocean as a further precaution, and LaGuardia Design Group restored the dunes.
When new owners bought the property for $11.7 million in 2017, they also tapped Stelle Lomont Rouhani and got a free-standing garage topped with a pool house. In charge of the interiors, Ms. Donnelly, 51, oversaw the painting of the walls. They are white, though the décor pops with pink and orange accessories. “There’s no rainbow of fruit flavors in our architectural palette,” Ms. Donnelly said, though she quickly added that color was possible at request.
A CEDAR HOUSE IN AMAGANSETT for George Yabu and Glenn Pushelberg, the Canadian interior designers, added exterior zinc-wall panels that are nontoxic, recyclable and reflect heat from the sun.
The couple owns homes in other places, but Mr. Yabu said they considered this one their “effortless” primary residence from late spring through October. “The beach is really us, and this time of year we yearn for it,” he said.
The upper level thrusts daringly toward the dunes while maintaining a respectful distance of five feet. The men wanted to step out of the lower level directly onto sand, so Mr. Stelle advised them to move fast and get grandfathered by the building department to keep the new structure “off stilts.”
They designed their own interiors, in a creative conversation with the architects that Mr. Yabu termed a “love fest.”
Now, a dozen years on, Mr. Stelle still brings colorful eggs freshly laid by his Araucana hens as a thank you when he arrives to show the house to prospective new clients. “Architects can be prickly, but he is supernice,” Mr. Pushelberg said.