This year’s Builder’s Choice entries are hard proof that modular housing is making serious inroads.

Prefab Prototype House impresses on good looks alone, thanks to the clever use of varied materials such as wood resin, corrugated metal, and insulated concrete blocks. Those materials are low maintenance, too. “Our goal was to create great modern architecture that was affordable and cost 25 percent less than our least expensive custom home designs,” says architect Steven Stept, managing principal of Swatt|Miers.

Precision and coordination are the linchpins of a modular project’s success, and Prefab Prototype House faced hurdles. Delivery was tricky: The site, on an infill lot, wasn’t accessible from the street—power poles and lines prevented delivering the modules and setting them in place. (For set day, an adjacent parking lot was used.)

The prefab design hews to the same principles of Swatt|Miers’ custom homes—indoor-outdoor connections, open plan, spatial variety of the interiors. The result? A home that thinks modular, but looks custom.

Learn more about markets featured in this article: San Francisco, CA.