A fire destroyed a garage being used for storage on a Sagaponack property on Saturday night. When the Bridgehampton Fire Department was called to the property at the northwest corner of Wainscott Harbor Road and Montauk Highway at 8:35 p.m., the wooden building was already engulfed in flames. Chief Tim Sieger said the department’s first priority was to contain the blaze, which threatened to spread to an unused barn behind the garage. The fire was quickly knocked down. The Sagaponack property is owned by John Birch, a furniture designer whose store is located across Wainscott Harbor Road, under the name Wainscott Harbor Farm L.L.C. He bought the property in 2015 from Ruth Mulford, whose family had lived there for over 100 years. The home near the shed dates to 1875, according to a book called “Sagaponack: Then & Now,” published in 2006. Sagaponack Village officials said they believed the garage was just as old