ADU Builder in San Jose
Looking for an ADU builder in San Jose? The city offers streamlined permitting and pre-approved plans that reduce approval time to 2-3 weeks. Custom Home builds detached, attached, and garage conversion ADUs throughout San Jose, starting from $200K for a garage conversion to $400K+ for a full detached unit.
How much does an ADU cost in San Jose?
San Jose ADU costs range from $200K-$250K for a garage conversion to $300K-$500K for a detached unit in 2026. Per-square-foot costs run $250-$400/sqft depending on finishes. Custom Home's two-phase process provides 3D visualization and exact pricing before construction begins.
Why San Jose is Ideal for ADU Construction
San Jose leads the Bay Area in ADU-friendly policies. The city recognized early that accessory dwelling units are critical to addressing the housing shortage, and responded with streamlined permitting, reduced fees, and pre-approved plan options that make building an ADU faster and more affordable than in most neighboring cities.
For homeowners, this translates to a faster path from idea to completed unit, lower permitting costs, and a strong rental market that makes the investment pencil out quickly.
Types of ADUs We Build in San Jose
Detached ADUs
A standalone structure in your backyard, typically 400-1,200 sqft. Detached ADUs offer the most privacy and design flexibility. They’re ideal for rental units, home offices, or multigenerational living. San Jose allows detached ADUs up to 1,200 sqft on most residential lots.
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 work well 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. Since the structure already exists, you save on foundation, framing, and roofing costs. San Jose’s permitting process for garage conversions is straightforward, and the city does not require replacement parking in most cases.
San Jose ADU Permitting Process
San Jose has made the ADU permitting process as straightforward as possible:
- Pre-application consultation with the Planning Department (optional but recommended)
- Submit plans through the ePlan online system
- Plan review takes 2-3 weeks for pre-approved plans, 4-6 weeks for custom designs
- Permit issuance after plan approval
- Construction inspections at key milestones
- Final inspection and certificate of occupancy
Custom Home manages the entire permitting process, from initial submittal through final inspection. Our team is familiar with San Jose’s requirements and prepares plans that pass review on the first submittal.
ADU Rental Income Potential in San Jose
San Jose’s rental market is strong for ADUs. Current market rates for ADU rentals in San Jose:
- Studio/1-bedroom ADU (400-600 sqft): $1,800-$2,500/month
- 1-bedroom ADU (600-800 sqft): $2,200-$3,000/month
- 2-bedroom ADU (800-1,200 sqft): $2,800-$3,500/month
At these rates, most ADU investments pay for themselves within 7-12 years through rental income alone, not counting the property value increase (typically 20-30% for homes with permitted ADUs). For a detailed breakdown of what drives costs, read our ADU cost guide for the Bay Area.
Pricing for ADU Construction in San Jose
San Jose ADU construction costs range from $200K for a basic garage conversion to $500K+ for a large detached unit with premium finishes. Per-square-foot costs run $250-$400/sqft. 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 Jose Permit Requirements
San Jose offers some of the Bay Area's most ADU-friendly permitting. The city provides pre-approved ADU plans that can reduce plan check to 2-3 weeks. Standard ADU permits take 4-6 weeks. San Jose waives impact fees for ADUs under 750 sqft and charges reduced fees for larger units. The city allows ADUs on any residential lot, including lots with existing ADUs (JADUs).
ADU Construction in San Jose: FAQ
How long does it take to build an ADU in San Jose?
Construction typically takes 4-6 months for a detached ADU and 2-3 months for a garage conversion. Add 1-2 months for design and permitting. Custom Home's pre-approved plan option can reduce the total timeline to 5-6 months from start to move-in.
Do I need a permit for an ADU in San Jose?
Yes, all ADUs in San Jose require building permits. The good news is that San Jose has streamlined the process with pre-approved plans and reduced impact fees. Custom Home handles the entire permitting process as part of our service.
Can I rent out my ADU in San Jose?
Yes. San Jose allows ADU rentals with no owner-occupancy requirement. Many homeowners earn $2,000-$3,500/month in rental income from their ADU, making it a strong investment that can offset mortgage costs.