The ADU’s stainless steel cladding makes it resilient in all types of weather. "The D.C. metro area has four distinct seasons—it rains a lot, snows a lot, and it gets hot in the summer—so we wanted to create a unit that was adaptable and sustainable," says David Lee, founder and CEO of design studio Aroom. The steel contrasts the primary residence in brick and light-blue siding, but the Yeons loved the idea of a refreshing and modern look for the backyard unit.