ADU Construction in Millbrae
Millbrae is an excellent location for ADU construction, with options ranging from $120K for a garage conversion to $500K+ for a large detached unit. Custom Home builds detached, attached, and garage conversion ADUs in Millbrae with full 3D visualization and itemized pricing through our two-phase process.
How much does an ADU cost in Millbrae?
Millbrae ADU costs range from $120K for a garage conversion to $500K+ for a large detached unit in 2026. Custom Home's two-phase process provides 3D visualization and exact pricing before construction begins.
Why Millbrae Is a Strong Market for ADU Construction
Millbrae’s transit connectivity and proximity to SFO make it a desirable location where housing demand consistently outpaces supply. Adding an ADU to your Millbrae property creates both rental income potential and flexibility for multigenerational living. Many post-war homes in Millbrae sit on lots that can comfortably accommodate a detached or attached ADU.
Custom Home builds ADUs in Millbrae with the same two-phase design-build process we use for custom homes. You see the complete design in 3D and receive itemized pricing before any construction begins.
Types of ADUs We Build in Millbrae
Detached ADUs
A standalone structure in your backyard, typically 400-1,200 sqft. Detached ADUs offer the most privacy and design flexibility. They work well for rental units, home offices, or multigenerational living. Construction costs in Millbrae typically range from $300K to $500K+.
Attached ADUs
Built as an addition to your existing home, sharing at least one wall. Attached ADUs are typically more cost-effective than detached units since they share structural elements with the main house. They are a good fit for family members who want proximity while maintaining separate living spaces.
Garage Conversions
Converting an existing garage into a living space is the most affordable ADU option in Millbrae, starting from $120K. Since the structure already exists, you save on foundation, framing, and roofing costs.
Millbrae ADU Permitting
Millbrae’s Building Division handles residential building permits with plan review typically taking 4-6 weeks. The city follows California’s streamlined ADU permitting requirements and accepts standard ADU designs for expedited review.
Custom Home manages the entire ADU permitting process in Millbrae, preparing plans that meet local requirements for efficient review and approval.
ADU Rental Income Potential in Millbrae
Millbrae’s location near BART, Caltrain, and SFO creates strong rental demand for ADUs. The transit connectivity makes Millbrae ADUs particularly attractive to commuters. Many ADU investments in the area pay for themselves over time through rental income, in addition to the property value increase that a permitted ADU provides.
Pricing for ADU Construction in Millbrae
Millbrae ADU construction costs range from $120K for a basic garage conversion to $500K+ for a large detached unit with premium finishes. Garage conversions are the most cost-effective option since the structure already exists. Custom Home provides itemized pricing during Phase 1 so you know every cost before committing.
Millbrae Permit Requirements
Millbrae's Building Division handles residential building permits with plan review typically taking 4-6 weeks. The city follows California's streamlined ADU permitting requirements and accepts standard ADU designs for expedited review. Custom Home handles the entire ADU permitting process, preparing plans that meet local requirements for efficient approval.
ADU Construction in Millbrae: FAQ
What does ADU construction cost in Millbrae?
ADU costs in Millbrae range from $120K for a garage conversion to $500K+ for a large detached unit. The biggest cost factors are ADU type, size, finishes, and utility connections. Custom Home provides itemized pricing during Phase 1 so you know every cost upfront.
How long does it take to build an ADU in Millbrae?
ADU construction in Millbrae typically takes 6-12 months from design to move-in. Garage conversions are fastest at 4-6 months, while detached units take 8-12 months including permits. Custom Home's design phase front-loads decisions to keep construction on schedule.
Can I rent out my ADU in Millbrae?
Yes. California law allows ADU rentals, and Millbrae does not require owner-occupancy for ADUs. Millbrae's proximity to BART, Caltrain, and SFO supports strong rental demand, making an ADU a solid investment.