Adu builder — 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 builder is a professional partner who manages the entire development process for your project. You need one if you want a turnkey experience rather than trying to manage architects and contractors yourself. We take your vision and turn it into a functional structure while handling the heavy lifting of construction management and oversight. We keep your project on track and within your budget. Exact pricing confirmed free on the call.
Frequently asked in San Mateo
Can I get an ADU for rent in San Mateo?
What are homes with in-law suites like in San Mateo?
Homes with in-law suites in San Mateo, California, offer independent living spaces, typically attached to or within the main residence. These suites usually include a bedroom, bathroom, and a kitchenette, providing privacy and convenience for family members or renters. Their construction must adhere to San Mateo's ADU guidelines. We help you find builders experienced in creating these functional additions.
What is an ADU unit in San Mateo?
What permits are needed for an ADU in San Mateo?
What is the permit cost for an ADU in San Mateo?
What are accessory dwelling units (ADUs) in San Mateo?
Are detached ADUs allowed in San Mateo?
Yes, detached accessory dwelling units are allowed in San Mateo, California, provided they meet specific city regulations. These rules govern size, placement on the lot, and access. A professional assessment can confirm your property's suitability for a detached ADU. We can help you find that expert to evaluate your site.
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, Edgewater, Fitchburg, Parkside, Shoreview — and every surrounding area.
Areas we serve
Browse by state, then city.
California (4)
All of California · Rialto · San Buenaventura (Ventura) · San Mateo · Vacaville