How Much Does an ADU Cost in Los Angeles, CA?

Construction Cost Breakdown

Building an ADU in Los Angeles costs between $220,000-$400,000 for new construction, with per-square-foot costs averaging $300-$500. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $100,000-$200,000, while prefab/modular ADUs fall in between at $120,000-$350,000.

Permit Costs & Timeline

Permit fees in Los Angeles are No flat ADU fee. The LADBS building permit fee is set by construction valuation under LAMC 91.107 Table 1-A: for a valuation between $100,000 and $500,000 the codified base is $395 plus $3.50 per $1,000 (about $1,445 on $300,000, or about $2,384 as a combined building-mechanical permit at 165% of that figure), plus plan check at 90% of the permit fee (91.107.3.1.1), a 2% plan-maintenance fee (91.107.4.3), a fire-hydrant fee of 0.22% of valuation on jobs of $50,000 or more (91.107.4.4), state seismic and green-code surcharges, and the City Planning General Plan Maintenance Surcharge, raised from 7% to 10% on June 9, 2026 (CF 09-0969-S4). Table 1-A amounts are indexed to CPI every July 1 (91.107.1.1), so run the LADBS Permit Fee Calculator for the current total. LAUSD developer fees of $5.38 per sq ft apply to an ADU larger than 500 sq ft from August 11, 2026 (about $4,300 on 800 sq ft). The review timeline is The city must tell you within 15 business days whether the application is complete and must approve or deny it within 60 days of a complete application, or it is deemed approved (Gov. Code 66317(a) as amended by SB 543, in force January 1, 2026; LAMC 12.22 A.33(c)(2); ZA Memo 143 Q.24). If the ADU is filed with a new house, the ADU permit may wait for the house permit. LADBS publishes no average ADU plan-check turnaround; the Standard Plan Program is described only as shortening plan check, with plan check: Electronic plan check through LADBS ePlanLA or in person at a Development Services Center; LADBS reviews building, residential and green code and zoning compliance in one ministerial review, and only conditions affected by the ADU that threaten health or safety must be corrected (Gov. Code 66322(b); ZA Memo 143 Q.25-Q.26). Fire sprinklers are not required unless the main house needs them (12.22 A.33(c)(10)); a new detached ADU must have solar panels under the state energy code (LADBS ADU page); the Fire Department requires a separate address for every unit including a JADU; a JADU needs an efficiency kitchen and, if it shares a bathroom, an interior door to the house. Impact fees are None for an ADU with 750 sq ft of interior livable space or less or a JADU of 500 sq ft or less; a larger ADU pays in proportion to the main house's floor area (Gov. Code 66311.5(c)(1), as renumbered by SB 543). In Los Angeles this covers the Dwelling Unit Construction Tax (LAMC 21.10.3) and Residential Development Fee (21.13.3); ADUs and JADUs are exempt from park fees (LAMC 12.33, Ordinance 186,481 Sec. 4-6) and the Affordable Housing Linkage Fee (19.18) at any size (ZA Memo 143 Sec. III.D). Sewer and water capacity charges are not impact fees: a conversion unit inside the house or garage pays no new connection or capacity charge, and any other ADU pays one proportional to its burden (66311.5(b), (d)-(e)); confirm the Sewerage Facilities Charge with the Bureau of Engineering. Pre-approved plans: Yes. LADBS's ADU Standard Plan Program listed 83 plans in its April 2026 list, 79 approved and 4 pending, from a 200 sq ft studio to 1,200 sq ft three-bedroom units, 8 of them two-story; one 455 sq ft one-bedroom plan is owned by the City and free to use, the rest are licensed from their designers. LADBS still reviews site-specific items (zoning, foundation) for each lot, and roof-deck plans may need extra setbacks in some zones.

Rental Income & ROI

A typical ADU in Los Angeles generates approximately $27,600 per year in rental income based on average 1-bedroom rents. At an average construction cost of $310,000, the estimated payback period is 11.2 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Los Angeles and varies by market (often less than build cost).

Ways to Reduce ADU Costs in Los Angeles