Accessory dwelling unit cost — 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
Pricing for an ADU is driven by the quality of finishes, the foundation type, and the complexity of your site’s terrain. Projects on flat, accessible lots are generally more affordable than those requiring significant grading or utility trenching. Exact pricing confirmed free on the call.
Frequently asked in San Mateo
What are the benefits of local ADUs in San Mateo?
Local ADUs in San Mateo offer significant benefits, including increased rental income potential and flexible housing for family members. They can also enhance property value. ADUs provide a cost-effective way to add living space in a high-demand market. We help you leverage these advantages in San Mateo.
How do I find an accessory dwelling unit near me in San Mateo?
Are there accessory dwelling unit grants available in San Mateo?
Accessory dwelling unit grants can be available, though they often vary by region and specific programs. While we don't directly administer grants in San Mateo, we can help you identify potential funding sources. Information on state or local initiatives may be accessible. We guide you on how to inquire about these opportunities.
What are the options for ADU housing in San Mateo?
ADU housing options in San Mateo include both attached and detached units. Attached ADUs can be additions to existing homes or conversions of garages. Detached ADUs are separate structures. We help you determine the best ADU housing solution for your property and needs in San Mateo.
What is the cost of an accessory dwelling unit in San Mateo?
Are modular ADUs a good option for San Mateo?
Modular ADUs can be an efficient option for San Mateo projects, offering faster construction times and potentially predictable costs. We can assess the suitability of modular units for your site and San Mateo's regulations. This ensures a smooth and compliant building process.
What are accessory dwelling unit homes like in San Mateo?
Accessory dwelling unit homes in San Mateo are designed to be independent living spaces, complementing the primary residence. They can range from studios to multi-bedroom units, offering privacy and functionality. We help create ADUs that enhance your San Mateo property.
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, Peninsula Village, College Terrace, Parkside — and every surrounding area.
Areas we serve
Browse by state, then city.
California (4)
All of California · Rialto · San Buenaventura (Ventura) · San Mateo · Vacaville