In Washington, D.C., where the height act of 1910 limits upward growth and residential blocks were built a century ago, development opportunities are few and far between. But local firm BLDUS has found a niche in alley dwellings, filling in one of the last untapped streams of potential real estate in the city. With a “farm-to-shelter” mentality, BLDUS designs structures that have a sustainable aesthetic and challenge mainstream stick-built construction.