Can You Convert a Garage to an ADU in San Jose? Eligibility Guide

Quick Answer: Yes, you can convert a garage to an ADU in San Jose. California law (AB 2221, SB 9) makes garage conversions one of the most permissive ADU types — setbacks are typically waived for existing structures. A 2-car garage (400–500 sq ft) becomes a studio or 1-bedroom ADU for $80,000–$155,000. The process takes 6–12 months including permits.

Garage to ADU Conversion in San Jose: Eligibility and Process

Garage conversions are the most affordable and fastest type of ADU. California law specifically protects garage-to-ADU conversions — cities cannot deny them based on setbacks if the existing garage structure is used. Here’s how to determine if your San Jose garage qualifies.

Eligibility Requirements

• Property type: Single-family or multi-family residential zoning (check City of San Jose General Plan)
• Garage size: A 1-car garage (200 sq ft) can become a studio JADU (Junior ADU). A 2-car garage (400–500 sq ft) becomes a full ADU
• Setbacks: Converting an existing garage: setbacks of the existing structure are grandfathered — no new setback compliance needed (per AB 2221)
• Parking replacement: San Jose cannot require you to replace the garage parking space as a condition of ADU approval (state law preempts this)
• Height: Existing 1-story garage stays at the same height; adding a second story to a garage requires meeting current height limits

What Changes During a Garage ADU Conversion

• Foundation: Existing slab is used; may need insulation below slab or moisture barrier
• Framing: New interior partition walls, header for new window/door locations
• Insulation: Walls, ceiling, and slab/subfloor insulation to meet Title 24 energy code
• Drywall and finishes: Interior drywall, texture, paint
• Electrical: New panel sub-feed or dedicated service; kitchen, bathroom, GFCI circuits
• Plumbing: New bathroom rough-in (toilet, shower, sink) and kitchen stub-outs
• Kitchen: Efficiency kitchen (JADU) or full kitchen with range (ADU)
• Exterior: Garage door replaced with a finished wall; new windows; new entry door
• HVAC: Mini-split heat pump for heating and cooling

Garage ADU Conversion Cost in San Jose

• 1-car garage JADU (studio): $55,000–$100,000
• 2-car garage ADU (1BR/1BA): $90,000–$160,000
• 2-car garage ADU with second story (2BR): $180,000–$320,000

Quartz Construction specializes in garage-to-ADU conversions in San Jose. Learn more about ADU construction. CSLB #1003436 | BBB A+ | 4.9⭐. Call (650) 749-7436 for a free garage ADU feasibility assessment.

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Quartz Construction & Remodeling | CSLB #1003436 | Licensed, Bonded & Insured

Phone: (650) 749-7436

Address: 1777 Hamilton Ave #1080, San Jose, CA 95125

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