A garage conversion is usually the lowest-cost path to an ADU in San Diego — $80,000-$200,000, versus $250,000-$450,000 for a new detached build — because the shell already exists.
Garage Conversion Cost in San Diego
Converting an existing garage in San Diego runs $80,000-$200,000. That's well under the $250,000-$450,000 typical cost of a ground-up detached ADU, because you're reusing the foundation, walls, and roof. The biggest variables are whether the slab and framing are sound, what utility/electrical upgrades are needed, and your finish level. Permit fees add IB-501 (August 2026), Table 501A: a detached ADU of 500 sq ft or less, or an attached ADU or JADU up to 1,100 sq ft, pays $3,512.92 plan check plus $2,228.29 inspection for the first 500 sq ft ($5,741.21) and $6.98 + $4.46 per sq ft above that (about $9,173 for an 800 sq ft attached unit). A detached ADU over 500 sq ft is billed at the single-dwelling-unit rate: $8,085.26 plan check plus $8,401.90 inspection ($16,487.16 flat up to 3,000 sq ft including attached accessory structures). Every project also pays the $737 General Plan Maintenance Fee, a $12.16 mapping fee, a 2.5-hour DIF-calculation review (about $442 at the $176.84 hourly rate), $529.71 per new address, water/sewer plan check of $176.57 (no meter change) or $353.13 (new meter), and state seismic and building-standards fees. School district fees apply to any ADU of 500 sq ft or more (IB-146). Express plan check costs $793.95 plus 1.5x the regular plan check fee. A converted unit rents for about $2,200-$2,700/mo (1BR) in San Diego.
The San Diego Garage Conversion Permit Process
A garage-to-ADU conversion in San Diego needs building permits even if the exterior is unchanged. Approval process: Ministerial building permit only (Process One); no planning hearing or public notice (SDMC 141.0302; IB-400). Steps: 1) confirm zone, Coastal Overlay Zone, fire hazard zone, transit priority area and Sustainable Development Area on ZAPP; 2) prepare plans per Project Submittal Manual Section 2A: site plan and vicinity map (IB-122), floor and roof plans, elevations, structural plans and calculations, Title 24 energy forms; 3) submit the General Application (DS-3032), Water Meter Data Card (DS-16) and Storm Water Checklist (DS-560) through the online Development Services portal as a Building Construction application; 4) pay project set-up fees, then DSD Planning, Engineering, Structural and (if needed) Fire review; 5) permit issuance, inspections and, for a JADU, a recorded JADU agreement. Inside the Coastal Overlay Zone an ADU that adds habitable area needs a Coastal Development Permit, issued with the building permit in the non-appealable area (SDMC 126.0708(c)); the city's CDP decision on an ADU is not appealable to the Coastal Commission The review timeline is State law: the city must approve or deny within 60 days of a complete application or the ADU is deemed approved (Gov. Code 66314, SB 543 effective January 1, 2026); pre-approved plans get a 30-day review (IB-400). DSD's live dashboard on September 18, 2026 showed about 2 days in intake, 12-18 calendar days for a first review (Structural 12, Combined 16, Planning and Engineering 18), 6-13 days per recheck and 2 business days for issuance; expect one or two correction cycles, with plan check: Fully digital plan check through the DSD online portal, with a single consolidated resubmittal after all disciplines finish a cycle. Fire sprinklers are required only if the main house has them; a detached ADU never triggers sprinklers in the existing house (141.0302(a)(6)); all bonus and affordable ADUs must be sprinklered (141.0302(d)(5)). A new detached, site-built ADU must include solar panels under the California Energy Code (they may go on the main house); conversions and JADUs are exempt. An ADU over four units on a lot triggers Mobility Choices review, and every ADU needs code-compliant refuse and recycling storage (SDMC 142.0801). Pre-approved plans: Yes. Under AB 1332 the city accepts three outside catalogs of pre-approved plans, the County of San Diego Standard ADU Plans, the City of Chula Vista Standard ADU Plans and the City of Encinitas Permit-Ready ADU Plans, with a 30-day review; the plans must be licensed from their designer and re-checked against current codes and the SDMC development standards (DSD ADU page; IB-400). Applicants may also have their own plans pre-approved for others through the master plan process in IB-114a; the city does not publish a count of such plans.
- Confirm eligibility — ADUs are allowed in Every base zone and Planned District zone whose use table lists ADUs as a limited use, which is generally every zone that allows residential use, including multiple-dwelling and mixed-use commercial zones (SDMC 141.0302; IB-400). JADUs are allowed only in single-dwelling-unit zones, or on a lot in a multi-unit zone that holds a previously conforming single-family home. Check your zone, Coastal Overlay, fire hazard and transit-priority status on the city's ZAPP map.
- Prepare conversion plans — layout, egress windows, insulation, ventilation, smoke/CO detectors, plus a kitchen and bathroom.
- Submit for plan check — Fully digital plan check through the DSD online portal, with a single consolidated resubmittal after all disciplines finish a cycle. Fire sprinklers are required only if the main house has them; a detached ADU never triggers sprinklers in the existing house (141.0302(a)(6)); all bonus and affordable ADUs must be sprinklered (141.0302(d)(5)). A new detached, site-built ADU must include solar panels under the California Energy Code (they may go on the main house); conversions and JADUs are exempt. An ADU over four units on a lot triggers Mobility Choices review, and every ADU needs code-compliant refuse and recycling storage (SDMC 142.0801).
- Pull permits and build — fees run IB-501 (August 2026), Table 501A: a detached ADU of 500 sq ft or less, or an attached ADU or JADU up to 1,100 sq ft, pays $3,512.92 plan check plus $2,228.29 inspection for the first 500 sq ft ($5,741.21) and $6.98 + $4.46 per sq ft above that (about $9,173 for an 800 sq ft attached unit). A detached ADU over 500 sq ft is billed at the single-dwelling-unit rate: $8,085.26 plan check plus $8,401.90 inspection ($16,487.16 flat up to 3,000 sq ft including attached accessory structures). Every project also pays the $737 General Plan Maintenance Fee, a $12.16 mapping fee, a 2.5-hour DIF-calculation review (about $442 at the $176.84 hourly rate), $529.71 per new address, water/sewer plan check of $176.57 (no meter change) or $353.13 (new meter), and state seismic and building-standards fees. School district fees apply to any ADU of 500 sq ft or more (IB-146). Express plan check costs $793.95 plus 1.5x the regular plan check fee; then framing, electrical, plumbing, and final inspection.
No Replacement Parking Required
No. California law (AB 68 / Gov Code §66314) prohibits cities from requiring replacement parking when you convert or demolish a garage to build an ADU — so you do not need to add a parking space anywhere on the lot. Owner-occupancy is not required, so you can rent the converted unit out.
The JADU Option for an Attached Garage
If your garage is attached to the house, you can convert it into a junior ADU (JADU) — capped at 150 to 500 sq ft, inside an existing or proposed single-family home or its attached garage; may expand the house by up to 150 sq ft for entry (141.0302(c)). JADU floor area does not count toward FAR. A detached garage cannot become a JADU and built within the existing walls. JADUs are cheaper and faster to permit than a full ADU, though they may share sanitation with the main home. A full ADU gives you more size and a separate unit; a JADU is the budget route.
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San Diego Garage Conversion FAQ
How much does a garage conversion cost in San Diego?
Do I need a permit to convert a garage in San Diego?
Do I have to replace the parking if I convert my garage in San Diego?
How long does a garage conversion take in San Diego?
Can I convert an attached garage into a JADU in San Diego?
Compare your options: see the full San Diego ADU rules, estimate your build with the San Diego ADU cost calculator, or read the general garage conversion guide.