ADU Rules: San Diego vs Los Angeles (2026 Comparison)
Compare ADU regulations between San Diego and Los Angeles. Both operate under California state law — but local implementation, fees, and permit timelines differ.
Side-by-Side Comparison
San Diego vs Los Angeles
| San DiegoCalifornia | Los AngelesCalifornia | |
|---|---|---|
| ADUs Allowed? | Yes, by right in all residential zones (CA state law) | Yes, by right in all residential zones (CA state law) |
| Max Detached ADU Size | 1,200 sq ft | 1,200 sq ft |
| Max Attached ADU Size | 50% of primary dwelling up to 1,200 sq ft | 50% of primary dwelling up to 1,200 sq ft |
| JADU Allowed? | Yes, up to 500 sq ft within existing structure | Yes, up to 500 sq ft within existing structure |
| Side/Rear Setbacks | 4 feet | 4 feet |
| Estimated Permit Fees | $2,500–$9,000 total permit fees | $2,000–$8,000 total permit fees |
| Permit Timeline | Ministerial approval within 60 days (typically 3-6 weeks) | LADBS ADU Express targets 2-4 weeks; 60-day state mandate |
| Impact Fees | Waived for ADUs under 750 sq ft; school fees above 750 sq ft | Waived for ADUs under 750 sq ft; school fees at $4.08/sq ft above 750 sq ft |
| Coastal Zone Overlay? | Yes — Coastal Development Permit required in Coastal Zone | No significant coastal zone overlay (small coastal areas only) |
| State Preemption? | Yes (CA Gov Code 65852.2) | Yes (CA Gov Code 65852.2) |
Key Differences
Both San Diego and Los Angeles operate under California's statewide ADU law (Government Code 65852.2), which creates a unified framework: 1,200 sq ft maximum, 4-foot setbacks, 60-day ministerial approval, and no owner-occupancy requirement. The core rules are identical because state law supersedes local restrictions. The key differences lie in local implementation. San Diego's geography creates a significant regulatory overlay: the California Coastal Zone covers large portions of coastal San Diego neighborhoods (La Jolla, Pacific Beach, Ocean Beach, Mission Beach). Properties in the Coastal Zone need a Coastal Development Permit (CDP) in addition to the standard building permit — this can add 2-4 months to the timeline and additional cost. Los Angeles has a much smaller coastal zone footprint. San Diego also uses 107+ community plan areas, each with local design guidelines. Los Angeles has 35 community plans and Historic Preservation Overlay Zones (HPOZs) that may require Certificate of Appropriateness for visible exterior modifications. LA has a slight edge in permit processing speed with its LADBS ADU Express service that targets 2-4 weeks for standard ADU plan check. San Diego's Development Services Department (DSD) offers a Standard ADU Plan Program for reduced review time, but LA's ADU Express program is more developed.
Cost Comparison
San Diego ADU construction typically runs $180,000–$380,000 — slightly higher than LA due to local labor market conditions and the coastal premium. Permit fees run $2,500–$9,000. Coastal Zone properties incur additional CDP costs ($500–$2,000+) and time. LA ADU construction typically runs $150,000–$350,000 with permit fees of $2,000–$8,000. Both cities waive impact fees for ADUs under 750 sq ft. School developer fees apply to ADUs 750+ sq ft: in LA at $4.08/sq ft residential rate; San Diego school fees vary by district. Neither city charges the SDC-type system development charges that inflate costs in Portland.
Our Verdict
Los Angeles wins on permitting speed and process clarity for most homeowners. LADBS ADU Express and the city's large contractor ecosystem make LA the smoother experience. San Diego is competitive on costs and similarly permissive under state law, but Coastal Zone complications can significantly delay and complicate projects for the substantial portion of San Diego homeowners in the Coastal Zone. If your property is not in San Diego's Coastal Zone, the two cities are closely matched. If it is, expect additional time and cost.
Explore Each City
Frequently Asked Questions
Do San Diego and LA have the same ADU rules?
The core rules are the same because both operate under California Government Code 65852.2. Maximum size (1,200 sq ft), setbacks (4 ft side/rear), no owner-occupancy requirement, and 60-day ministerial approval all apply equally. Local differences include coastal zone overlays, community plan design standards, and permit processing speed.
What is the Coastal Development Permit requirement in San Diego?
Properties in the California Coastal Zone — which covers La Jolla, Pacific Beach, Ocean Beach, Mission Beach, and other coastal San Diego neighborhoods — require a Coastal Development Permit (CDP) in addition to standard building permits. The CDP process can add 2-4 months and $500–$2,000+ in fees. Check your parcel's Coastal Zone status at the San Diego DSD website.
Which city processes ADU permits faster?
Los Angeles's LADBS ADU Express service targets 2-4 weeks for standard ADU plan check. San Diego's DSD Standard Plan program also reduces review time. Both cities are subject to California's 60-day ministerial approval requirement. LA has a slight edge in processing speed due to its dedicated ADU Express program and larger permit processing staff.
Are there impact fees for ADUs in San Diego and LA?
Impact fees are waived for ADUs under 750 sq ft in both cities per California Government Code 65852.2(f)(3). ADUs 750 sq ft or larger are subject to school developer fees. LA charges $4.08/sq ft (residential rate). San Diego school fees vary by school district. Neither city charges the system development charges (SDCs) common in Oregon cities.
Source: PropertyZoned Editorial Research. Last verified April 5, 2026. View source