An 1870s Clinton Hill carriage house that was transformed into the city’s very first mass timber home has sold for $7 million — after hitting the market last November for $7.5 million. The seller, Aaron Schiller, was also the architect. Schiller, of Schiller Projects. He and his wife bought the 21-foot-wide home at 329 Vanderbilt Ave., which is part of the Clinton Hill Historic District, for $2.75 million in 2018. …New York banned timber towers in the 19th century over fire concerns, Schiller, a Yale-educated architect, was part of an advisory group indirectly helping the city council make changes. By 2021, the New York City Council approved mass timber for buildings up to 85 feet high. Glue-laminated timber is far better for the environment than steel and concrete — if the trees are sustainably harvested and disposed of responsibly at the “end of life.” …The home is anchored by a Douglas fir staircase. The three-bedroom, 3½-bath residence is 3,050 square feet.