What does accessory dwelling unit mean — 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 accessory dwelling unit is a secondary housing unit on a single-family residential lot. It can be attached to your home, like a basement apartment, or detached in your backyard. People ask this when they are starting to explore ways to increase their property's utility or income potential. It is essentially a complete living space with its own kitchen, bathroom, and entrance. Exact pricing confirmed free on the call.
Frequently asked in San Mateo
What are the accessory dwelling unit services available in San Mateo?
Accessory dwelling unit services in San Mateo include design, permitting assistance, construction, and project management. These services ensure your ADU meets all local San Mateo and California state requirements. They provide a comprehensive solution for adding this valuable living space to your property. Get expert guidance.
Who is an accessory dwelling unit contractor in San Mateo?
What are the accessory dwelling unit companies in San Mateo?
Accessory dwelling unit companies in San Mateo are businesses specializing in the design and construction of ADUs. They offer a range of services from initial planning to final completion. Look for companies with a strong reputation and a portfolio of successful ADU projects in the area. They simplify the process.
What is the accessory dwelling unit permit cost in San Mateo?
The accessory dwelling unit permit cost in San Mateo can vary based on the project's scope and complexity. Permit fees are set by the city and cover the review and inspection process. These costs are part of the overall budget for your ADU. Get a detailed quote for your project.
Where can I find ADU near me in San Mateo?
What are the benefits of emergency ADU services in San Mateo?
Emergency ADU services in San Mateo are crucial for immediate repairs to ensure the safety and habitability of an accessory dwelling unit. This could involve urgent structural issues, plumbing leaks, or electrical problems. Prompt professional response prevents further damage and ensures the unit is safe for occupants. It provides peace of mind.
Are there 24-hour ADU services in San Mateo?
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, Shoreline, Downtown San Mateo, College Park, 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