Occupying an in-fill lot at the end of an alley, this duplex offers a pair of 2-bedroom 2-bath units with open loft-like spaces and several outdoor areas that take advantage of San Diego’s temperate climate. Steel brace frames on a concrete block base are clad with wood-fiber panels. Radiant heating is imbedded in the exposed concrete floor, while polycarbonate panels flank the open stair and allow for filtered natural light.