What's Required in San Diego
- Building permit required for every ADU and JADU; no exemptions (IB 400)
- ADU 150 to 1,200 sq ft; JADU 150 to 500 sq ft inside the house or attached garage
- Side and rear setback 4 ft when the ADU exceeds 16 ft next to residential property or sits in a Very High Fire Hazard Severity Zone; front setback of the zone always applies
- Detached ADUs limited to two stories on single-dwelling lots; overall height per the base zone
- No parking required outside the Coastal Overlay Zone; garage conversion needs no replacement parking
- Site plan, floor and roof plans, elevations, structural plans and calculations, Title 24 energy calculations, DS-3032, DS-16 and DS-560
- Solar panels required on newly built detached ADUs; sprinklers only if the primary dwelling has them (all bonus and affordable ADUs sprinklered)
- Rentals must be 31 days or longer; owner occupancy required only with a JADU that shares a bathroom with the house
- JADU Agreement recorded before permit issuance; Coastal Development Permit in the Coastal Overlay Zone
Do You Need a Permit for an ADU in San Diego?
Always. Information Bulletin 400 says a Building Permit is required to create an ADU or JADU; there are no exemptions, and for a one- or two-unit house it is a Combination Building Permit covering the trades. The rules are in San Diego Municipal Code section 141.0302, summarized in IB 400 (January 2026). An ADU is 150 to 1,200 square feet; a junior ADU is 150 to 500 square feet inside the house or an attached garage. A single-dwelling lot may have one attached or detached ADU, one conversion ADU, and one JADU. ADUs count toward floor area ratio, but one ADU of up to 800 square feet may be built even over the FAR cap, and a conversion is not subject to the 1,200-square-foot limit. No parking is required outside the Coastal Overlay Zone, and a converted garage needs no replacement spaces. A new ADU keeps the zone's front setback but may run to the side and rear lines if 16 feet or lower; taller than 16 feet next to residential property, or anywhere in a Very High Fire Hazard Severity Zone, it holds a 4-foot side and rear setback. Detached ADUs are capped at two stories.
San Diego ADU Rules by Scenario
| What you are doing | City filing | Rule |
|---|---|---|
| Detached new ADU up to 500 sq ft, or attached ADU or JADU up to 1,100 sq ft | Combination Building Permit; Addition/Remodel fee line | IB 400; IB 125; IB 501 Table 501A |
| Detached new ADU over 500 sq ft | Combination Building Permit; new-dwelling fee line | IB 501 Table 501A |
| Garage or accessory-structure conversion | Building permit; keeps existing setbacks; not subject to the 1,200 sq ft cap; may add 150 sq ft for entry | IB 400 |
| ADU using a City-accepted preapproved plan | Building permit with a 30-day review | IB 400; AB 1332 |
| ADU in the Coastal Overlay Zone that adds habitable area | Coastal Development Permit, issued with the building permit in the non-appealable area | IB 400 |
| Bonus ADUs beyond the base allowance | Deed-restricted affordable ADU plus one bonus ADU each; agreement with the Housing Commission before permit | SDMC 141.0302(d); IB 400 |
| ADU built without a permit before January 1, 2020 | Retroactive permit under AB 2533 | IB 242 |
How Much Does an ADU Permit Cost in San Diego?
Fees are flat by size on Information Bulletin 501, Table 501A. A detached ADU up to 500 square feet, or an attached ADU or JADU up to 1,100 square feet, uses the Addition/Remodel line: $3,512.92 plan check and $2,228.29 inspection for the first 500 square feet, then $6.98 and $4.46 per square foot. A detached ADU over 500 square feet uses the new single-dwelling line: $8,085.26 plan check and $8,401.90 inspection up to 3,000 square feet. Every ADU also pays the $737.00 General Plan Maintenance Fee (applied to ADUs since August 9, 2022) and a $12.16 mapping fee. Worked examples: a 500-square-foot detached ADU is about $3,512.92 + $2,228.29 + $737.00 + $12.16 = $6,490.37; an 800-square-foot attached ADU is $5,606.92 plan check (300 extra square feet at $6.98) plus $3,566.29 inspection, about $9,922 with the two fees; an 800-square-foot detached ADU is about $8,085.26 + $8,401.90 + $749.16 = $17,236.32. IB 501 also lists a 2.5-hour impact-fee assessment charge ($442.10 at $176.84 per hour), state fees of 13 cents per $1,000 of valuation and $1 per $25,000, and a $17.11 collection charge.
Fees That Are Not the Permit
School fees are set and collected by the school district, not the city; an ADU or JADU creating less than 500 square feet of assessable space is exempt. Section 142.0640(b)(1) exempts ADUs under 750 square feet, JADUs, and in any case the first two ADUs on a premises regardless of size from Development Impact Fees, unless built under SB 9. Projects with more than one ADU pay Regional Transportation Congestion Improvement Program fees. A newly built detached ADU needs solar panels; conversions and additions do not. Sprinklers are required only if the main house has them; all affordable and bonus ADUs are sprinklered.
Review Time and Who Files
Government Code 66317 gives the city 15 business days to confirm completeness and requires it to approve or deny a complete ADU application within 60 days; otherwise it is deemed approved. Preapproved plans get a 30-day review. Applications go on the DSD portal as a Building Construction record with site, floor, roof and structural plans, Title 24 documents and forms DS-3032, DS-16 and DS-560. A contractor or the owner-builder with form DS-3042 may hold the permit. An ADU may not be rented for less than 31 days; the owner need not live on site for an ADU, but must for a JADU unless the JADU has its own bathroom.
How to Get a ADU Permit in San Diego
Check the lot on ZAPP
Confirm zone, Coastal Overlay, fire zone, Sustainable Development Area status and floor area ratio before designing.
Size and place the unit
Stay within 1,200 sq ft, the zone's front setback and the 16-ft or 4-ft side and rear rule; conversions keep existing setbacks.
Prepare plans and forms
Architectural, structural and Title 24 documents with DS-3032, DS-16, DS-560 and DS-3042 if you are the owner-builder; or license a City-accepted preapproved plan.
Apply and pay plan check
File a Building Construction application on the DSD portal; $3,512.92 or $8,085.26 plan check and the $737.00 General Plan Maintenance Fee are due before the 60-day review clock.
Pay issuance fees, build and inspect
Inspection fees, school fee proof and any water and sewer fees are due at issuance; impact fees, if any, before final inspection.