Adu unit — 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
An ADU unit is simply another term for a secondary dwelling unit located on the same lot as a primary residence. Whether it is a conversion of a garage or a brand-new structure, the unit serves as an independent living space with its own kitchen and bath. Homeowners often add these units to increase property value or house guests comfortably. Exact pricing confirmed free on the call.
Frequently asked in San Mateo
How do accessory dwelling units differ in older versus newer San Mateo properties?
What are the costs to build an accessory dwelling unit in San Mateo?
Can you recommend an accessory dwelling unit contractor in San Mateo?
What does 'accessory dwelling unit' mean for homeowners in San Mateo?
For San Mateo homeowners, an 'accessory dwelling unit' (ADU) means a secondary, independent living space on their property. This could be a detached backyard cottage, an attached unit, or a converted garage. ADUs offer opportunities for rental income, multigenerational living, or housing for caregivers. Understanding this concept unlocks property enhancement possibilities.
What services are available for ADU construction in San Mateo?
Are there 24-hour ADU services in San Mateo?
What are the benefits of local ADU services in San Mateo?
Local ADU services in San Mateo offer the advantage of professionals who understand the city's specific zoning laws and building requirements. They are familiar with the local housing market and common property types. This local expertise ensures a smoother permitting process and a construction project tailored to San Mateo's environment. Call to connect with a local expert.
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: Bay Meadows, The Village, Downtown San Mateo, Shoreview, Edgewater Isle — and every surrounding area.
Areas we serve
Browse by state, then city.
California (4)
All of California · Rialto · San Buenaventura (Ventura) · San Mateo · Vacaville