The cedar-clad two-story main house, with its matching half-moon front-and-back decks, was designed by Horace Gifford, renowned for his modernist cedar-and-glass refuges on Fire Island, and completed in 1979. An extension designed by Philip Babb in cedar, glass, and lead-coated copper was added from 1994 to ’96, with comprehensive renovations also made to the original house. A bridgelike structure connects both sections, and the array of wraparound decks seamlessly blends the exterior structure into a single statement. Walls of south-facing windows and glass sliders provide water vistas throughout the house, while north-facing windows overlook the front lawn and gardens. There are six bedrooms, six baths, two fireplaces, four cedar decks, a sauna, laundry facilities on both floors, an outdoor kitchen and a hot tub on the shaded lower deck, and a two-car garage. A Har-Tru tennis court overlooks Little Seatuck Creek on the west side of the property. The house is upside-down style, with the living and entertainment areas reached by a floating cedar staircase. Three of the six bedrooms are downstairs, as are the sauna, four baths and a recreation room that opens onto the shaded deck by the pool. Upstairs, the 40-by-20-foot great room has 10-foot ceilings, a fireplace with a German stone surround, and an open kitchen with maple cabinetry, a stone floor, granite countertops and stainless-steel appliances. Glass doors open onto the twin 35-by-17-foot decks: one faces the water; the other faces the lawn and curves around a massive maple tree. The original bedroom section just off the living room has 17-foot ceilings. The two cedar-clad bedrooms share a bath, and the larger has sliders to the south deck and a ladder to a loft. The newer master suite is at the southwest side of the house. It has 11-foot ceilings, a fireplace, a walk-in closet with built-in cedar shelving and walls of glass overlooking the waterways. The bedroom section is 18 by 16 feet and opens onto Mr. Graham’s 16-by-14-foot home office, which has a curved wall of glass and steel with southern and western exposures. The master bath, finished in white subway tile, has a soaking tub beneath a north-facing window, a corner glassed-in steam shower and a double vanity.