Modular accessory dwelling 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
A modular ADU is built in a factory and then transported to your property to be assembled on a foundation. You should consider this if you want a faster construction timeline and less disruption in your backyard. Because the units are built off-site, they are often cost-effective and efficient. We help you choose the right model and ensure the site is ready for delivery. Exact pricing confirmed free on the call.
Frequently asked in San Mateo
What are the requirements for an emergency ADU in San Mateo?
Is 24-hour ADU service available in San Mateo?
What are prefab ADUs and their benefits in San Mateo?
Can I rent out an ADU in San Mateo?
Yes, renting out an ADU is a primary benefit for many San Mateo homeowners. Local regulations generally permit ADUs to be leased, providing a valuable source of rental income. Ensure you comply with all landlord-tenant laws and city ordinances. Your ADU can become a significant asset.
What is the permit process for an ADU in San Mateo?
Are there ADU grants available in San Mateo?
While specific ADU grants can fluctuate, it's advisable to explore any available programs from San Mateo County or the state of California. These might be tied to affordability or specific construction types. Inquiring about potential funding can reduce your project's financial burden. We can help you identify potential resources.
What does accessory dwelling unit mean?
An accessory dwelling unit (ADU) is a secondary, independent living unit on a single-family lot in San Mateo. This can be attached to the main home or a separate structure like a backyard cottage. ADUs provide complete living facilities. They offer flexibility for tenants or family members.
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: Laurel Creek, Bay Meadows, Downtown San Mateo, Hillsborough, Shoreview, Edgewater — and every surrounding area.
Areas we serve
Browse by state, then city.
California (4)
All of California · Rialto · San Buenaventura (Ventura) · San Mateo · Vacaville