Accessory dwelling unit builders near me — San Mateo, CA

Last updated: September 24, 2026

What affects the price

Building an ADU involves several moving parts that shape your total budget. The biggest factor is whether you choose a prefabricated unit or a custom build on-site. Site preparation is also significant; if your land requires extensive grading, utility trenching, or foundation work, costs will climb. Your choice of finishes—like kitchen cabinetry, flooring, and siding materials—also shifts the bottom line. We help you navigate these variables to find a setup that fits your property. Exact pricing confirmed free on the call.

About this service

Local builders provide the labor and project management needed to turn an empty backyard space into a functional living area. You need them when you have a vision for a guest house or rental but need a team familiar with your specific regional climate and local building department inspectors. Hiring nearby crews often simplifies logistics and ensures that your builder has established relationships with local supply houses and inspectors.

Frequently asked in San Mateo

Also serving nearby: Hayward · Daly City · Oakland · Sunnyvale · Fremont

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More on this: HUD ADU resources — ADU policy and financing research.

Service area details

Serving all of San Mateo — population 101,327; about 8,350 residents per square mile across 12.1 sq mi. ZIP codes covered include 94401, 94402, 94403, 94404, 94497.

Neighborhoods served in San Mateo: Downtown San Mateo, Bay Meadows, Shoreview, Aragon, Laurel Creek — and every surrounding area.