Accessory dwelling unit companies — 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
ADU companies offer end-to-end solutions, often handling everything from the first sketch to the final walk-through. You need these companies if you prefer a streamlined experience where one firm takes responsibility for design, permitting, and construction. They are ideal for homeowners who want to minimize the stress of managing multiple vendors and prefer a turnkey approach to adding a secondary residence to their property.
Frequently asked in San Mateo
What are homes with mother-in-law suites like in San Mateo?
Homes with mother-in-law suites in San Mateo are properties that feature a separate, secondary living unit. These suites can be attached to the main house or be a detached structure. They offer independent living spaces with their own kitchens and bathrooms. ADUs are often built to serve this purpose.
What is an accessory dwelling unit in San Mateo?
An accessory dwelling unit (ADU) in San Mateo is a secondary housing unit on a single-family residential lot. It's a self-contained living space with its own kitchen, bathroom, and entrance. ADUs can be attached to the primary home or be a separate structure. They provide flexible housing options.
Where can I find an accessory dwelling unit near me in San Mateo?
Are accessory dwelling unit grants available in San Mateo?
Accessory dwelling unit grants may be offered through state or local initiatives in California. These programs aim to incentivize ADU development. It's advisable to check with the city of San Mateo or consult with ADU experts for current information on available grants. They can guide you on eligibility.
How do I get an ADU quote in San Mateo?
Are prefabricated accessory dwelling units a good option for San Mateo?
Prefabricated ADUs can be a smart choice for San Mateo due to their efficiency. They are built in a factory, which often leads to faster on-site assembly and consistent quality. This can be particularly beneficial in denser urban environments. Discuss this with your chosen pro.
What is a detached accessory dwelling unit?
A detached accessory dwelling unit is a separate structure on a property, independent of the main house. It typically has its own entrance, kitchen, and bathroom. Detached ADUs offer maximum privacy for occupants and can be built in various configurations. They are a common ADU type.
Also serving nearby: Hayward · Daly City · Oakland · Sunnyvale · Fremont
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: Aragon, Bay Meadows, Edgewater, Peninsula Point, Shoreview, Westlake — and every surrounding area.
Areas we serve
Browse by state, then city.
California (4)
All of California · Rialto · San Buenaventura (Ventura) · San Mateo · Vacaville