This $3.5 million Sag Harbor address is the first foray into single-family homes by a prolific Manhattan architecture firm.

Traditional and modern elements in the 3,500-square-foot residence are bridged by a dramatic glass breezeway, which contains the stairs and the entrance to the four-bedroom, 5.5-bath home designed by Andrew Sheinman and David Griffin of the firm Pembrook & Ives.

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“They sort of re-created what would be a Sag Harbor clapboard kind of house that is traditional,” says listing agent Jack Pearson of The Corcoran Group. “Because the lot is very deep and goes to the other street behind, it enabled them to make a modern barn behind it with lots of glass and high ceilings and really interesting, modern living spaces.”

A first-floor master bedroom suite in the traditional wing opens to a private garden with a small deck, Pearson says. Two more en-suite bedrooms with high cathedral ceilings are located directly above the master suite on the second floor.

A lower-level great room, accessible through the breezeway, includes deep, well windows on both sides and a full bathroom. In the modern wing, the lower level features an open design where the kitchen — with lacquered wood cabinetry and a “huge” central island — and the living and dining rooms function as one.

A glass-enclosed breezeway connects a house and another structure in this Sag Harbor property. It is on the market in August 2016 for $3.5 million. Photo Credit: The Corcoran Group / Chris Foster

Upstairs, a second master suite includes a large deck overlooking an evergreen-lined yard. The property includes a square pool and a pool house cabana with barn doors, which, on the opposite side, is a two-car garage.