Zoning & Size Limits
| Requirement | Los Angeles, CA | San Diego, CA |
|---|
| Allowed Zones | All residential zones (R1, R2, R3, R4, R5, RD, RW, RE, RS, R | All residential zones; also allowed in some commercial mixed |
| Max Size (Detached) | 1,200 sq ft | 1,200 sq ft |
| Max Size (Attached) | 1,200 sq ft or 50% of primary dwelling | 1,200 sq ft or 50% of primary dwelling |
| Max Height | Detached: 16 ft base (18 ft within 1/2 mi of trans | 2 stories, with height set by the underlying base/ |
| Parking Required | No parking required (eliminated statewide by AB 68) | No parking required, except 1 off-street space in the Coasta |
| Owner Occupancy | Not required (CA state law — permanent, no sunset provision) | Not required |
Setback Requirements
| Setback | Los Angeles, CA | San Diego, CA |
|---|
| Rear Setback | 4 ft for units ≤16 ft height | 4 ft |
| Side Setback | 4 ft for units ≤16 ft height | 4 ft |
| Front Setback | Must meet primary dwelling front setback | Per underlying zone |
Permits & Timeline
| Detail | Los Angeles, CA | San Diego, CA |
|---|
| Permit Timeline | 60-day ministerial review (state-mandated) | 60 days (often faster) |
| Permit Fees | $4,000-$15,000 depending on size and type (plus 10% General Plan Maintenance Surcharge on permit fees as of June 9, 2026) | $3,500-$12,000 |
| Impact Fees | Waived for units under 750 sq ft (state law) | Waived for units under 750 sq ft |
| Pre-Approved Plans | Yes — LA has a Standard Plan Program with pre-appr | Yes — companion unit program with pre-approved des |
Construction Costs
| Cost | Los Angeles, CA | San Diego, CA |
|---|
| Avg Build Cost | $150,000-$350,000 | $120,000-$300,000 |
| Cost Per Sq Ft | $200-$400 | $180-$350 |
| Garage Conversion | $80,000-$180,000 | $70,000-$160,000 |
| Prefab ADU | $100,000-$250,000 | $90,000-$220,000 |
Rental Income Potential
| Rental | Los Angeles, CA | San Diego, CA |
|---|
| 1BR Avg Rent | $1,800-$2,500/mo | $1,600-$2,200/mo |
| 2BR Avg Rent | $2,200-$3,200/mo | $2,000-$2,800/mo |
| Short-Term Rentals | Restricted — STR rules apply; host must be primary resident | Not allowed for ADUs — minimum 31-consecutive-day lease (Inf |
| Est. ROI | 6-10% annual return | 7-11% annual return |
Which City Is Better for ADUs?
Los Angeles scores 9/10 while San Diego scores 9/10 on our ADU-friendliness index.
Both cities offer viable ADU development opportunities — the best choice depends on your specific property, budget, and goals.
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