Hawthorne, CA Accessory Structures: ADU Rules (2026)
ADU rules in Hawthorne, CA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Max ADU size
- 1,000 sq ft (500 sq ft for a JADU)
- Min ADU size
- 220 sq ft
- Max height
- 16 ft, one story
- Side/rear setback
- 4 ft minimum
- Parking
- 1 space, often waived (§ 17.21.060 Note 9)
- Minimum rental term
- 30 consecutive days
- Review process
- Ministerial, no hearing, director decides
Summary
Hawthorne allows one accessory dwelling unit on any single-family lot and up to two ADUs on multifamily lots, reviewed ministerially by the planning director with no public hearing. Size, height, and setback standards are fixed by Table 17.21.060 under Municipal Code Chapter 17.21.
An ADU or JADU is permitted in any residential or mixed-use zone that allows residential units. Sites developed or proposed to be developed with a single-family residence shall not be permitted more than one ADU. Sites developed with a multifamily building may convert existing non-habitable square footage within the building to a minimum one ADU and a maximum that shall not exceed twenty-five percent of the number of units on the site.
Full Breakdown
Hawthorne Municipal Code Chapter 17.21 governs ADUs and junior ADUs (JADUs) citywide. An ADU or JADU is permitted in any residential or mixed-use zone that allows residential units (§ 17.21.050(A)). A single-family lot gets one ADU maximum; a multifamily lot can convert non-habitable space into a minimum of one and up to 25% of the existing unit count, plus construct two new detached ADUs or convert garages, carports, or covered parking to a maximum of two ADUs (§ 17.21.050(C)). Only one JADU is allowed per single-family site, and none if the site already has an attached ADU (§ 17.21.050(D)).
Table 17.21.060 sets a 220-square-foot minimum size for both attached and detached ADUs, a 1,000-square-foot maximum (500 square feet for a JADU), a maximum height of 16 feet and one story, and minimum 4-foot side and rear yard setbacks. Detached ADUs need 6-foot separation from both accessory and primary buildings. Only one off-street parking space is required per ADU, and it is waived entirely if the unit sits within a half-mile walk of public transit, in a historic district, is part of the existing primary residence or an accessory structure, or a car-share vehicle is within one block (Note 9). Demolishing a garage for an ADU does not trigger a replacement-parking requirement (Note 10).
Section 17.21.040 puts approval in the hands of the director of planning and community development: applications are reviewed ministerially, without notice or a public hearing, after payment of a nonrefundable review fee set by city council resolution, and the director's written decision is final. Section 17.21.070 requires ADUs to sit to the rear of the primary residence and be architecturally compatible with the neighborhood when visible from the public right-of-way, bars a certificate of occupancy for the ADU before one issues for the primary dwelling, and bars the city from conditioning ADU approval on correcting existing nonconforming zoning. Rentals may not run less than 30 consecutive days (§ 17.21.070(H)), and a JADU requires a recorded deed restriction before a building permit issues (§ 17.21.080).
Violations & Fines
An ADU or JADU built or altered without the required accessory dwelling unit permit and building permit (§ 17.21.030) is subject to code enforcement as an unpermitted structure. A JADU sold separately from the primary dwelling, or an ADU/JADU conveyed apart from the lot, violates the deed restriction recorded under § 17.21.080 and the no-separate-conveyance rule in § 17.21.070(I). Renting either unit for stays under 30 consecutive days violates § 17.21.070(H) and can trigger the city's short-term rental enforcement alongside ADU permit revocation review by the planning director.
Frequently Asked Questions
Can I build more than one ADU on my Hawthorne property?
How much parking does a Hawthorne ADU need?
Can I rent my Hawthorne ADU out short-term?
Does the city hold a public hearing before approving my ADU?
Sources & Official References
Other rules in Hawthorne
How Hawthorne compares: Easiest Cities to Build an ADU·California rules heatmap·Compare Hawthorne to another location·View the California accessory structures overview
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