Unincorporated only: This page covers the unincorporated area of Los Angeles County — parcels outside any city, regulated by the County Planning / Land Use Services Department. If your address is inside a city (Los Angeles, Long Beach, Pasadena, Glendale, Burbank, Santa Monica, Torrance), use that city's ADU page instead.
These rules apply to UNINCORPORATED Los Angeles County - East Los Angeles, Altadena, Hacienda Heights, Rowland Heights, South Whittier, Florence-Firestone, Willowbrook and similar communities - not the City of Los Angeles, Pasadena, Long Beach or any of the county's other 87 incorporated cities, which each apply their own ADU code. Under County Code Title 22 Sec. 22.140.640 (last amended by Ord. 2025-0029, effective August 28, 2025) a single-family lot may add one attached ADU, one detached ADU and one JADU; any new ADU is capped at 1,200 sq ft and 25 ft, with 4 ft side and rear setbacks, and no parking is required outside a Very High Fire Hazard Severity Zone. Approval is ministerial: a Regional Planning Site Plan Review filed on EPIC-LA ($1,496 under the March 1, 2026 fee schedule) decided within 60 days of a complete application, then a Building & Safety permit. Where Title 22 conflicts with state ADU law (Gov. Code 66310-66342), state law controls (Sec. 22.140.640 L).
Zoning & Size Requirements [1][2][3][4][5]
Yes — unincorporated Los Angeles County allows ADUs. A detached ADU can typically be up to 1,200 sq ft under California state law and the County's zoning code.
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| Where ADUs Are Allowed | Any zone that allows residential use, on a lot with an existing or concurrently proposed single-family or multifamily residence (Sec. 22.140.640 B and Table 22.140.640-A); Coastal Zone lots follow the applicable Local Coastal Program. In a Very High Fire Hazard Severity Zone a local-standard ADU needs two separate 24 ft wide vehicular routes to a highway, or direct highway frontage - the state-exempt ADUs in subsection H are allowed regardless of access (subsection C). |
| Max Size (Detached) | 1,200 sq ft maximum floor area for any new ADU (G.1.a.ii); minimum 150 sq ft with one habitable room of at least 70 sq ft. No maximum when an existing accessory structure is converted with no more than 150 sq ft added for entry and exit. The state-exempt detached ADU (H.1.a.ii) is 800 sq ft or less with 4 ft side and rear setbacks and is approved without other local standards, including in fire hazard zones. |
| Max Size (Attached) | 1,200 sq ft, the same uniform cap as detached ADUs since Ord. 2025-0029 (Aug 28, 2025); no maximum for an ADU created entirely within the existing house or apartment building (G.1.a.ii.1.b). CSD, Planning Area Standards District and Specific Plan floor-area and lot-coverage limits do not apply to ADUs (G.1.a.ii.2). The Fire Department reviews a house-plus-attached-ADU over 3,600 sq ft total (Building & Safety ADU Guidelines). |
| Max Size (JADU) | 500 sq ft of interior livable space (Gov. Code 66313 as amended by SB 543), entirely within the existing or proposed single-family residence including an attached garage, with an efficiency kitchen and its own exterior entrance; the bathroom may be shared with the house if the JADU has interior access to it (H.2). One JADU per single-family lot; none on multifamily lots. Building & Safety issues no separate address or utility meter for a JADU. |
| Max Height | 25 ft for an attached or detached ADU on a single-family or multifamily lot (G.1.b.i); no limit for an ADU inside the existing residence or a same-footprint conversion. Where a CSD, Planning Area Standards District or Specific Plan sets a lower cap, the county must still allow 16 ft for a detached ADU, 18 ft (+2 ft for a matching roof pitch) within a half-mile walk of major transit, and 18 ft on a multifamily lot; within 200 ft of a scenic route, the lesser of the house height or 18 ft. |
| Max Units | Single-family lot: 1 ADU attached to or within the house or an accessory structure + 1 detached ADU + 1 JADU (Table 22.140.640-A). Multifamily lot: attached or interior ADUs up to 25% of the principal units (rounded up) plus detached ADUs - the code table says 2, but the county's SB 1211 memo (Nov 25, 2024) and April 29, 2026 ADU Summary allow up to 8, not exceeding the number of existing units; no JADUs on multifamily lots. AB 2533 amnesty units do not count toward these caps. |
Setback & Parking Requirements [1][2][3][4][5]
Unincorporated Los Angeles County requires a rear setback of about 4 ft for a detached ADU, and parking requirements vary by unit size or location. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 4 ft for any new ADU or expanded portion of a structure (G.1.c.iii); no setback for an ADU entirely within the existing residence or a conversion or same-size rebuild of an existing accessory structure (G.1.c.ii). Eaves and similar projections follow Sec. 22.110.090 but may come no closer than 2.5 ft to the lot line. |
| Side Setback | 4 ft from interior and corner side lot lines; an ADU built above a garage must be 4 ft from a reversed-corner side lot line; ADUs are exempt from Title 22 step-back rules (G.1.c.iii). Consult Building & Safety on fire-rated construction for any wall closer than 4 ft to the line (county ADU Summary, April 29, 2026). |
| Front Setback | The zone's or CSD's standard front setback, except that an ADU of 800 sq ft or less may encroach into the front setback if there is no other place on the lot to build it at ground level (G.1.c.i). In any Fire Hazard Severity Zone an ADU must sit at least 200 ft from publicly dedicated open space, but an 800 sq ft ADU with 4 ft setbacks must still be allowed (G.1.e). |
| Parking Required | None outside a Very High Fire Hazard Severity Zone; none for a JADU. In a VHFHSZ, one uncovered space (Ch. 22.112; county ADU Summary) unless the ADU has no bedroom, is within a half-mile walk of public transit, is in a historic district, is part of the residence or an accessory structure, street permits are withheld from it, a car-share is within a block, or it is filed with a new house (G.1.d). No replacement parking when a garage or carport is demolished or converted; tandem parking allowed. |
| Owner Occupancy | ADUs: not required - Sec. 22.140.640 has no ADU owner-occupancy rule and subsection I releases the county's old owner-occupancy covenants. JADUs: the county code requires the owner to live in either the house or the JADU, recorded by covenant, and bars JADUs on corporate-owned lots (H.2.e-f); state AB 1154 (Gov. Code 66333, effective Jan 1, 2026) limits that requirement to JADUs that share a bathroom with the house, and Sec. 22.140.640 L says state law controls where they conflict. |
| Min Lot Size | None in Sec. 22.140.640. CSD and Specific Plan floor-area, gross structural area and lot-coverage limits do not apply to ADUs or JADUs (G.1.a.ii.2, H.2.b.ii), and approval cannot be conditioned on correcting nonconforming zoning conditions on the lot (subsection K). |
Permit Process & Fees [6][7][8][9][10][11]
An ADU in unincorporated Los Angeles County is approved administratively — no public hearing. Typical timeline: Regional Planning decides within 60 days of a complete application including fee payment (Sec. 22.140.640 D; Gov. Code 66317 adds a 15-business-day completeness notice and deems the ADU approved if the 60 days lapse); Building & Safety plan check follows with no published target. Permit fees: Regional Planning's ministerial Site Plan Review for a residential site plan is $1,496, or $1,995 inside a CSD, hillside or other special district (fee schedule effective March 1, 2026); Building & Safety plan-check and permit fees are valuation-based on top, with no flat ADU rate.
| Approval Process | Ministerial, no hearing. File a 'DRP - Base Application - Permits and Reviews' with a site plan on the EPIC-LA portal (epicla.lacounty.gov) for Regional Planning's ministerial Site Plan Review, then building plan check and permit through Public Works Building & Safety, also on EPIC-LA for unincorporated areas. JADUs need a recorded county covenant; any discretionary permit the lot needs (e.g., an Oak Tree Permit) must be approved first, and lots with a Conditional Use Permit file a ministerial Revised Exhibit A. |
| Review Timeline | Regional Planning decides within 60 days of a complete application including fee payment (Sec. 22.140.640 D; Gov. Code 66317 adds a 15-business-day completeness notice and deems the ADU approved if the 60 days lapse); Building & Safety plan check follows with no published target. |
| Permit Fees | Regional Planning's ministerial Site Plan Review for a residential site plan is $1,496, or $1,995 inside a CSD, hillside or other special district (fee schedule effective March 1, 2026); Building & Safety plan-check and permit fees are valuation-based on top, with no flat ADU rate. |
| Impact Fees | The county publishes no ADU-specific impact fee. Gov. Code 66311.5(c) bars any impact fee on an ADU with 750 sq ft or less of interior livable space or a JADU of 500 sq ft or less, and any fee above 750 sq ft must be proportional to the main house; school district fees apply only above 500 sq ft of new habitable area, and utility connection or capacity charges are not impact fees. Sanitation District and water 'will serve' clearances are still required. |
| Plan Check | Building & Safety plan check needs architectural and structural plans plus Title 24 energy calculations; single-story garage conversions can use the county's standard notes and details, single-story detached ADUs can follow the wood-frame provisions, and two-story, hillside or basement ADUs need a design professional. Sprinklers only if the main house has them (R313.2) or if ADU plus attached garage exceeds 1,200 sq ft (Fire Department); new detached ADUs need solar under Title 24. |
| Pre-Approved Plans | Yes - the county's free Standard ADU Plans catalog has 3 plans pre-approved by Regional Planning and Building & Safety: Plan A (1,200 sq ft, 3 bed/1 bath), Plan B (1,200 sq ft, 2 bed/1 bath) and Plan C (800 sq ft, 1 bed/1 bath); you add a site plan and file on EPIC-LA. The Private Designer Catalog is offline until its plans are updated for the building codes that took effect January 1, 2026. |
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Construction Costs [12][13][14]
Building an ADU in unincorporated Los Angeles County typically costs $170,000-$350,000 ($280-$450 per sq ft); a garage conversion runs $80,000-$180,000.
See what this means for your lot — ask Los Angeles County ADU builders for a quote →
Construction costs in unincorporated Los Angeles County track the surrounding metro market. Rural parcels can cost more because of septic, well, access and fire-hazard requirements, so treat these as planning ranges and get local bids.
| Average Build Cost | $170,000-$350,000 |
| Cost per Sq Ft | $280-$450 |
| Garage Conversion | $80,000-$180,000 |
| Prefab ADU (Installed) | $120,000-$250,000 |
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Rental Income Potential [15][16]
| Avg Rent (1 Bedroom) | $1,900-$2,900/mo |
| Avg Rent (2 Bedroom) | $2,300-$3,600/mo |
| Short-Term Rental | No - County Code Sec. 22.140.770 E (Ord. 2024-0054) lists ADUs and JADUs among the habitable accessory structures that may not be used as short-term rentals, and Sec. |
| Est. Annual ROI | 6-10% gross annual yield (estimate) |
Recent Law Changes
What's Changed Recently
- August 28, 2025: Ordinance 2025-0029 (adopted July 29, 2025) took effect - uniform 1,200 sq ft cap for attached and detached ADUs, 25 ft height on multifamily lots, ADUs of 800 sq ft or less may encroach into front setbacks, unpermitted structures may be converted, state-exempt ADUs allowed in Very High Fire Hazard Severity Zones regardless of road access, objective standards for historic properties, and a full comment list on any denial
- June 17, 2025: the Board approved permit-fee deferrals and refunds for owner-occupants rebuilding fire-destroyed homes in unincorporated areas, including ADUs - even where the ADU was the only structure lost - and a standalone ADU the owner will occupy while the house is rebuilt
- January 1, 2026: SB 543 (Gov. Code 66317: 15-business-day completeness notice, 60-day decision, deemed approved if missed; 66311.5: no impact fees on ADUs of 750 sq ft or less of interior livable space) and AB 1154 (JADU owner-occupancy only where the JADU shares a bathroom; JADU rentals over 30 days) took effect - the county's April 29, 2026 ADU Summary still shows the older JADU owner-occupancy rule
- March 1, 2026: Regional Planning's revised fee schedule took effect - ministerial residential Site Plan Review $1,496 (was $1,452); special-district review $1,995
- March 3, 2026: the Board of Supervisors approved $3.8M in state funding for ADU construction grants to 35-50 unincorporated-area homeowners, focused on Eaton Fire areas and run with a nonprofit housing partner; units must stay affordable to middle-income households for 10 years and be started or finished by the end of 2030
- July 2026: the county's draft 2026 ADU Ordinance Amendment (aligning Title 22 with state law and exploring state authority to limit ADUs on certain subdivided lots) is in 'draft evaluation' with no hearing scheduled; the 2025 ordinance and state law continue to govern. HCD's December 1, 2025 findings letter on the county ordinance could not be read at verification - Sec. 22.140.640 L already makes state law control where Title 22 conflicts
Tips for Building an ADU in Unincorporated Los Angeles County
- East Los Angeles, Altadena, Hacienda Heights, Rowland Heights, South Whittier, Florence-Firestone, Willowbrook, Walnut Park and other unincorporated communities follow the County code; the City of Los Angeles, Pasadena, Long Beach, Glendale and every other incorporated city has its own ADU rules - check your address on the county's Find My Zoning page first
- Eaton Fire survivors: if you owned and lived on the lot before January 7, 2025, the county defers or refunds zoning review, building plan-check, permit, inspection, Fire and Public Health fees for a rebuilt home and its ADU (not for rental or multifamily properties) - email the Request for Fire Rebuild Fee Deferral or Refund form to recovery@planning.lacounty.gov. A like-for-like ADU rebuild may grow up to 10% or 200 sq ft; anything larger follows current Title 22 and the Altadena CSD with a 20 ft front setback. Do not assume AB 462 early occupancy applies: Gov. Code 66328(b) covers only emergency proclamations made on or after February 1, 2025 and excludes attached ADUs - get the One-Stop Permit Center to confirm in writing
- Use one of the 3 free county Standard ADU Plans (1,200 sq ft 3-bed, 1,200 sq ft 2-bed, or 800 sq ft 1-bed): the building plans are already checked, so you only supply a site plan and the Regional Planning review
- Keep the ADU at 750 sq ft or less of interior livable space to avoid impact fees under Gov. Code 66311.5(c), and at or below 500 sq ft of new habitable area to avoid school district fees; sprinklers are not required unless the main house has them or ADU plus attached garage exceeds 1,200 sq ft
- In a Very High Fire Hazard Severity Zone (much of Altadena and the foothills), a local-standard ADU needs two separate 24 ft wide access routes to a highway - if your lot fails that test, the 800 sq ft state-exempt detached ADU or a conversion inside the house must still be approved, and one parking space applies unless you are within a half-mile walk of transit or another exemption fits
- Cost basis (2026-09-20): avg build $170,000-$350,000 for a 600-800 sq ft new detached ADU from LA-area guides dated March, June and July 2026 ($280-$450 per sq ft all-in; hillside or historic lots higher); garage conversion $80,000-$180,000; prefab $120,000-$250,000 installed. Rents are HUD FY2027 Small Area Fair Market Rents (effective Oct 1, 2026) for unincorporated ZIPs: 1BR $1,890 (Florence-Firestone 90001) to $2,900 (Altadena 91001), 2BR $2,330 to $3,580; East LA 90022 $1,910/$2,360, Rowland Heights 91748 $2,390/$2,950, Hacienda Heights 91745 $2,780/$3,430
- Cost basis (2026-09-20 re-verification): short term allowed: No - County Code Sec. 22.140.770 E (Ord. 2024-0054) lists ADUs and JADUs among the habitable accessory structures that may not be used as short-term rentals, and Sec. 22.140.640 F.2 allows an ADU or JADU to be rented only for more than 30 consecutive days; AB 1154 sets the same 30-day floor for JADUs statewide.
ADU Builders in Los Angeles County
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Cities Within Los Angeles County
If your property is inside one of these incorporated cities, follow that city's ADU code — not the County rules above:
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Los Angeles County Code Title 22 Sec. 22.140.640 - Accessory Dwelling Units and Junior Accessory Dwelling Units (Municode, code version Sept 2, 2026; Ord. 2025-0029 Sec. 8) Municipal Code — Accessed 2026-09-20
- LA County Regional Planning - Accessory Dwelling Unit (ADU) Summary (revised April 29, 2026) Planning Department — Accessed 2026-09-20
- LA County Regional Planning - ADU Ordinance Amendment informational memo (Ord. 2025-0029, adopted July 29, 2025, effective Aug 28, 2025) Planning Department — Accessed 2026-09-20
- LA County Regional Planning - 2026 ADU Ordinance Amendment (draft evaluation phase, updated July 2026) Planning Department — Accessed 2026-09-20
- California Government Code 66328 (AB 462, effective Oct 10, 2025) - certificate of occupancy for an ADU before the primary dwelling State Law — Accessed 2026-09-20
- LA County Regional Planning - Revised Filing Fees effective March 1, 2026 Planning Department — Accessed 2026-09-20
- LA County Regional Planning - Standard ADU Plans Program, County Catalog (Plans A, B, C) Planning Department — Accessed 2026-09-20
- LA County Public Works Building & Safety - ADU Guidelines v4.1 (Oct 10, 2024) and ADU program page Planning Department — Accessed 2026-09-20
- LA County Recovers - Fee Deferrals & Refunds for Eaton and Palisades fire rebuilds (Board motion June 17, 2025) Planning Department — Accessed 2026-09-20
- SB 543 (Stats. 2025, ch. 520) - Gov. Code 66317 timelines and 66311.5 impact fees, effective Jan 1, 2026 State Law — Accessed 2026-09-20
- AB 1154 (Stats. 2025) - JADU owner-occupancy and 30-day rental floor, effective Jan 1, 2026 State Law — Accessed 2026-09-20
- How Much Does an ADU Cost in Los Angeles? 2026 Price Guide (March 28, 2026) - CCS Construction Consulting Services industry — Accessed 2026-09-20
- ADU Cost in Los Angeles 2026 (updated June 2026) - ADUscale industry — Accessed 2026-09-20
- ADU Cost Guide Los Angeles (updated July 28, 2026) - GreatBuildz industry — Accessed 2026-09-20
- HUD FY2027 Small Area Fair Market Rent Schedule, Los Angeles-Long Beach-Glendale HUD Metro FMR Area ZIP codes (effective Oct 1, 2026) Government Data — Accessed 2026-09-20
- Los Angeles County Code Title 22 Sec. 22.140.770 - Short-Term Rentals (Ord. 2024-0054) Municipal Code — Accessed 2026-09-20
- LA County Regional Planning - Accessory Dwelling Units program page Planning Department — Accessed 2026-09-20
- LA County Regional Planning - Eaton Fire disaster recovery Planning Department — Accessed 2026-09-20
- Supervisor Kathryn Barger (County of Los Angeles) - Board approves $3.8 million to help fire survivors build ADUs (March 3, 2026) Government Data — Accessed 2026-09-20
Frequently Asked Questions
What are the ADU rules in unincorporated Los Angeles County?
In unincorporated Los Angeles County, ADUs are regulated by the County (not a city) and follow California state ADU law. A detached ADU can be up to 1,200 sq ft maximum floor area for any new ADU, attached ADUs up to 1,200 sq ft, the same uniform cap as detached ADUs since Ord. 2025-0029. Rear setbacks are 4 ft for any new ADU or expanded portion of a structure, and qualifying ADU applications are approved administratively, with no public hearing.
How much does an ADU permit cost in Los Angeles County?
In unincorporated Los Angeles County, building and plan-check fees scale with the size and valuation of the ADU, so there is no single flat fee — request the current fee schedule from the County. The county publishes no ADU-specific impact fee. Gov. Code 66311.5(c) bars any impact fee on an ADU with 750 sq ft or less of interior livable space or a JADU of 500 sq ft or less, and any fee above 750 sq ft must be proportional to the main house; school district fees apply only above 500 sq ft of new habitable area, and utility connection or capacity charges are not impact fees. Sanitation District and water 'will serve' clearances are still required.. Total construction typically runs $170,000-$350,000; a garage conversion is cheaper at $80,000-$180,000.
Do I need owner-occupancy for an ADU in Los Angeles County?
ADUs: not required - Sec. 22.140.640 has no ADU owner-occupancy rule and subsection I releases the county's old owner-occupancy covenants. JADUs: the county code requires the owner to live in either the house or the JADU, recorded by covenant, and bars JADUs on corporate-owned lots (H.2.e-f); state AB 1154 (Gov. Code 66333, effective Jan 1, 2026) limits that requirement to JADUs that share a bathroom with the house, and Sec. 22.140.640 L says state law controls where they conflict..
Is my property in unincorporated Los Angeles County or inside a city?
This matters a lot: if your parcel is inside an incorporated city (Los Angeles, Long Beach, Pasadena, Glendale, Burbank, Santa Monica, Torrance), that city's ADU code applies instead of the County's. Only unincorporated parcels follow the County rules on this page. Confirm your jurisdiction with the County before designing.
How many ADUs can I build in unincorporated Los Angeles County?
Single-family lot: 1 ADU attached to or within the house or an accessory structure + 1 detached ADU + 1 JADU (Table 22.140.640-A). Multifamily lot: attached or interior ADUs up to 25% of the principal units (rounded up) plus detached ADUs - the code table says 2, but the county's SB 1211 memo (Nov 25, 2024) and April 29, 2026 ADU Summary allow up to 8, not exceeding the number of existing units; no JADUs on multifamily lots. AB 2533 amnesty units do not count toward these caps.
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