Developers have not used wood for much other than houses since the horse-and-buggy days. But the knotty building material is making a comeback. Seeking greener projects, which many consumers continue to embrace despite an anti-environmental mood in Washington, builders are choosing timber for offices, apartments and campus buildings, rather than the concrete and steel that dominated construction for decades. …Concerns persist about wood’s flame resistance and strength, as well as its cost, which can be 30 percent more than traditional materials. But proponents scored a huge win last month when the International Code Council, an influential advisory group in Washington, concluded that some wooden buildings could climb as high as 18 stories without compromising safety. …Winning acceptance for mass timber seems especially challenging in New York, which appears to have lagged other cities in proposals. But a handful of projects are underway in Brooklyn.