In the last 10 years, the stakes in the Perfect Hamptons House Pageant have risen to a record high. Shingled McMansions have sprung up, decorated in the all-American vernacular whose idols are Ralph Lauren and Martha Stewart. More modest Modernist houses built in the 1950's and 60's have come back into vogue, preaching the gospels of Charles Eames and Calvin Klein. And with each new house, the same questions are always asked:Is this the authentic Hamptons? Will the ultimate beach house please stand up?

The time has come to admit that the Hamptons have as much to do with authenticity as a Culver City back lot. Near the East Hampton Airport, star architects like Shigeru Ban and Zaha Hadid are designing idiosyncratic houses for a new development, with prices in the multimillions. And on Further Lane in East Hampton, Jerry Seinfeld has run afoul of local zoning laws by installing a regulation baseball field on a lot without the requisite accompaniment of a substantial building.

Fantasy, it seems, is the new vernacular.

If so, a few mailboxes down from Mr. Seinfeld, a beach house garishly un-Hamptons in its clash of cultures — Nantucket and Rio de Janeiro, for starters — exemplifies a new kind of spirit for '04. The creation of Joe Nahem, a Manhattan decorator (with some input from his companion, Jeffrey Fields, a catalog marketing executive), the house, a renovation, is an off-kilter mélange of simple bucolic beachiness and city-style luxuries. Or as the colorfully blunt Mr. Nahem describes it in his Brooklyn accent, "Cool stuff that looks good."

The house, with its kitschy 1960's references and its deluxe materials (a pair of old gnarled driftwood stools, for example, upholstered in sky-blue cowhide), has caused a minor stir. After all, humble whitewashed rafters and flooring made of recovered lumber are not often paired with fancy Italian modern furniture and populuxe upholstery.

Relatively modest at 4,200 square feet, on little more than an acre, the house has a youthful lack of pretension and an infectious quality of fun. Dull on the outside — a benign white cedar-sided shell with a 70's look, which is actually new construction — on the inside the house offers breezy, subtly hued spaces opening onto long decks with views of the ocean.

The only duty one feels in Mr. Nahem's house is to have a margarita and go sit on the deck or wander down to the pool and pavilion at the far end of the property, just yards from the beach. It is a great place for a party — and will accommodate 50 people, as he and Mr. Fields proved in May

"Joe's hit the perfect note," said Julie Taubman, the socially prominent wife of Robert Taubman, who, almost as soon as the varnish was dry, rented the four-bedroom house from Mr. Nahem for the rest of the summer for herself, her husband and four children. "I looked at a lot of houses. It was really hard to find a house that had all the comforts, with a really stylish environment, and at the same time one that's not so much so that you can't sit anywhere in a bathing suit."

But it is not just the easy mood or the theatricality of the house's midcentury Malibu-Barbie style that makes it a draw. With the project, Mr. Nahem is coming out from under the shadow of his late business partner, Tom Fox, who was killed in April 2003 in a plane crash in Massachusetts. Mr. Nahem said that during their 20-year partnership, he was considered the tough, brass-tacks businessman and Mr. Fox the smooth and amiable Southern gentleman.

he accident — which also killed the New York real estate developer M. Anthony Fisher, his wife, Anne, and Michael Campanelli, an assistant at Fox-Nahem Design — occurred just as the Fox-Nahem partnership started being celebrated, with projects appearing in rapid succession on the covers of magazines like House & Garden, House Beautiful and Elle Décor. And it occurred on Mr. Nahem's birthday, just as he had begun remodeling his house from the foundation up.

Some — Mr. Nahem among them — were unsure that he could deal with the business on his own.

"Tom was Joe's mentor — there's no doubt about that," said Luigi Caiola, a real-estate developer who hired Fox-Nahem to design a house in Wainscott on Long Island and an apartment in the Chelsea section of Manhattan. "He always looked for Tom's approval, without question."

Mr. Nahem said the loss of Mr. Fox was devastating.

"The grief was so intense," he said. "One day it's your birthday, and the next day your best clients, your partner and your assistant are all dead. I just immersed myself in business."

A year later, Mr. Nahem's own house is evidence that he can carry on the style he and Mr. Fox evolved together, a style that merges a European ethic of high-end design (and their beloved French 1940's furniture) with a chrome-plated-Cadillac feeling of comfort.

Mr. Nahem and Mr. Fields bought the original house on the property, an unimpressive 1,800-square-foot 1950's beach pad, for $1.2 million seven years ago. They lived in it on weekends for six years, until Mr. Nahem decided to turn it into a dream house. Little remains of the original structure but a downstairs bedroom. The new structure was designed with Steve Chrostowski, an architect at the Manhattan firm of Alveary Architecture.

The playfulness comes in with the furnishings. In the living room, in one corner, is a table by the craftsman George Nakashima and a curved organic sofa designed by Mr. Nahem after a James Mont chair. Across the room, by the driftwood stools, is a $400 garage-sale sofa upholstered in $2,000 worth of white vinyl.

"That's where I fall asleep — and drool," Mr. Nahem said.

Either sofa looks ready for a lie-down with Danielle Steel's latest — but visitors are advised to bring their own books. "We don't do a lot of reading here," Mr. Nahem said. True to his word, the only book around is "The Fat Flush Plan," a strict diet book from 2001.

A pair of nameless, armless 50's chairs face the windows. At the center of it all is an open dry-stacked stone fireplace reminiscent of a beach shack in Carmel, Calif. The dining room has little more than a Saarinen white-marble table and matching chairs (which came with the old house). The kitchen, which turns its back on the trend to robe every expanse in stainless steel, has a massive black walnut counter custom made by Mr. Nakashima's daughter, Mira Nakashima.

pstairs, the master bedroom is paneled in pecky cypress, whose arch weathered-beach-shack look seems right for the driftwood floor lamp complete with taxidermy marlin. But flanking the lamp are a pair of Art Deco chairs — "supposedly Royère," Mr. Nahem said skeptically — whose two-toned upholstery recalls a 60's Miami high-rise. The bed, designed by Mr. Nahem, is high enough to let them see a swath of blue ocean. Another bedroom contrasts colorful fabrics from Lulu DK and a Donghia jute wall covering reminiscent of corrugated cardboard.

The house is on a little hill, giving a better view of the dunes and the ocean beyond. Down the hill, nearer the beach, is the pool, anchored by a soaring new pavilion, complete with an outdoor fireplace and changing rooms.

Given the level of detail, the place feels remarkably casual. But Mr. Nahem said that though it is as scaled-down as he wanted it to be, it has all the bells and whistles of the projects he does for his clients. "I see all my clients becoming such slaves to all the gadgets — the alarm system, the central vacuum system, the TiVo in every room, the remote that turns the pool heater on from the house," he said. "And I vowed I wasn't going to do any of it. But in the end, I put it all in.

Why? "I don't know," he said. "You just get caught up in it. Plus, I knew it wouldn't hurt the resale value."

But he said he was still trying to get used to the fact that it belongs to him and Mr. Fields. His brass-tacks cynicism is just part of his peculiarly candid style. He is that rare decorator who refers to the bathroom as "the john" and does nothing to cultivate an aura of a landed-gentry past. Despite living in a house that is now worth several million dollars, he said, "You never know, I could be selling bedspreads out of my trunk tomorrow — or scooping ice cream with a hairnet on."

Now that his showplace is done, however, Mr. Nahem is not sure what drove him to finish it. "You want to have a good example of what you do," he said. "And I wanted the things that I have been doing for clients for myself."

For the rest of the summer, though, he does not have to worry about scooping ice cream. With his 2004-style beach house rented for the season, he and Mr. Fields are moving to a more modest place a few blocks away with a pool but no ocean view.

Mr. Nahem is the sort of fellow who, it appears, rests a bit easier watching the bottom line than the waves.