Step Inside Designer Gideon Mendelson's Sagaponack Home

In the octagonal home office, a Sputnik chandelier hangs above custom built-in furniture; the cushion fabric is from Lee Jofa. The ceiling treatment is by Silvère Boureau and wall coverings are by Romo. The 1825 globe, by renowned English globe maker John Cary, is from Kentshire Galleries.

In the living room, matching custom sofas by Mendelson are covered in a Rogers & Goffigon linen; the drapery fabric is from Osborne & Little.

A second sitting area features a 1940s Jean Pascaud chair and a Nada Debs–designed Pebble cocktail table from Antony Todd.

Custom curved benches in a Gastón y Daniela fabric surround a Lee Jofa table in the library. The early-1900s teardrop lantern is amber bent glass and bronze. Ceiling paper is Osborne & Little's Sakura.

In the breakfast nook, a Holly Hunt table is matched with four reproduction Edward Wormley caned oak armchairs from Lorin Marsh.

Three white enamel factory lights from Ann-Morris Antiques illuminate the kitchen island; the Chilewich runner is from In Home.

A trio of antique wood cogs mark the staircase landing. The wool zebra-pattern runner is from Patterson, Flynn & Martin.

In Owen’s room, Carleton V’s Havana wall covering provides the backdrop for distressed antique pine twin beds from Summer Hill. The mid-1950s Danish desk is from Home 114.

The vintage tripod lamp in the master bedroom is from Schorr & Dobinsky; the drapes are made from a Beacon Hill linen.

A custom bench in the mudroom is topped with a cushion covered in a brightly striped Zoffany cotton. The jelly jar pendant lamp is from Remains Lighting.

On a corner of the porch, an antique mirror reflects the property’s verdant grounds. The console is from Mecox.

Maison Gatti bistro chairs and a Restoration Hardware table lend a French ambiance to an outdoor dining area.