About this build.
This detached accessory dwelling unit (ADU) in Castro Valley, in Alameda County, California, is a modern two-story backyard home with two bedrooms, two bathrooms, and a loft living room, built by Burton Builders in 2025. Bright, open, and designed for comfort, it lives far larger than a typical ADU — the loft adds a second space for relaxing or entertaining, overlooking the main level below. Outside, mixed gray lap siding and white stucco, a dramatic angled roofline with deep eaves, and a cantilevered upper balcony with a steel-cable railing give it real architectural presence, while a wall of black-framed windows opens the home to the backyard and pool.
Inside, a double-height great room is flooded with daylight from a two-story window wall, finished with white walls, wide-plank floors, and a linear fireplace set into a gray feature wall beneath the loft. A black steel open-riser stair and matching horizontal-rail loft railing add a crisp, industrial edge. The kitchen goes bold with matte-black flat-panel cabinetry, stainless appliances, and a striking gray-and-white marbled stone slab that runs from counter to backsplash, and ductless mini-splits keep every room comfortable year-round.
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