Adu construction — 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
This is the physical process of building your unit, including foundation work, framing, and utility hookups. You need this when you have your designs finalized and permits approved. Construction costs are influenced by the choice of materials, your local labor rates, and the accessibility of your property. We ensure the work is done to code and completed as efficiently as possible. Exact pricing confirmed free on the call.
Frequently asked in San Mateo
What are the benefits of modular accessory dwelling units?
Modular ADUs offer significant advantages, including faster construction timelines and potentially more predictable costs. Units are constructed in a controlled factory environment, leading to high quality. This method also minimizes on-site disruption. It's an efficient way to add valuable living space. Ask about modular options for your San Mateo ADU.
What is the accessory dwelling unit cost in San Mateo?
The accessory dwelling unit cost in San Mateo is influenced by size, design complexity, and chosen materials. Site conditions and necessary utility upgrades also factor into the final price. We provide a detailed, no-obligation quote. Contact us to schedule your project assessment.
What makes an ADU the best choice for my property?
What does prefab ADU mean?
Prefab ADU stands for prefabricated accessory dwelling unit. This means the unit is largely constructed off-site in a factory. It's then transported to your property and assembled. Prefab options can offer speed and cost efficiencies. We can discuss prefab solutions for your project.
What are the advantages of homes with mother-in-law suites?
Mother-in-law suites, a type of ADU, provide private, independent living quarters for family members. This allows for close proximity while maintaining separate spaces. These suites can also serve as rental units. They enhance a home's versatility and value. Call us to explore building one.
What ADU services do you offer in San Mateo?
What is the accessory dwelling unit permit cost 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: Baywood, Edgewater, Shoreview, Howard Park, Downtown San Mateo — and every surrounding area.
Areas we serve
Browse by state, then city.
California (4)
All of California · Rialto · San Buenaventura (Ventura) · San Mateo · Vacaville