ADU Construction in San Carlos
San Carlos is a popular choice 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 San Carlos with full 3D visualization and itemized pricing through our two-phase process.
How much does an ADU cost in San Carlos?
San Carlos 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 San Carlos Is a Great Fit for ADU Construction
San Carlos is a family-friendly community with a strong mix of mid-century and ranch-style homes, many of which sit on lots well suited for ADU construction. Adding a guest house, rental unit, or home office creates both flexibility and value in a neighborhood where demand for housing remains high.
Custom Home builds ADUs in San Carlos 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 San Carlos
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 San Carlos 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 San Carlos, starting from $120K. Since the structure already exists, you save on foundation, framing, and roofing costs. Many San Carlos ranch homes have two-car garages that convert well into comfortable living spaces.
San Carlos ADU Permitting
San Carlos processes residential building permits through its Community Development Department. The city follows California’s streamlined ADU permitting requirements, with typical plan review taking 4-6 weeks for standard designs.
Custom Home manages the entire ADU permitting process in San Carlos, preparing plans that meet local requirements for efficient review and approval.
ADU Rental Income Potential in San Carlos
San Carlos sits in a high-demand rental market along the Caltrain corridor, supporting strong returns for ADU owners. Proximity to downtown San Carlos and transit makes ADUs here particularly attractive to renters. 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 San Carlos
San Carlos 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.
San Carlos Permit Requirements
San Carlos processes residential building permits through its Community Development Department. The city has adopted California's streamlined ADU permitting requirements, with typical plan review taking 4-6 weeks for standard designs. San Carlos requires compliance with setback and height regulations for ADUs. Custom Home handles the entire ADU permitting process, preparing plans that meet local requirements for efficient approval.
ADU Construction in San Carlos: FAQ
What does ADU construction cost in San Carlos?
ADU costs in San Carlos 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 San Carlos?
ADU construction in San Carlos 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 San Carlos?
Yes. California law allows ADU rentals, and San Carlos does not require owner-occupancy for ADUs. San Carlos's location along the Caltrain corridor supports strong rental demand, making an ADU a solid investment.