Accessory Structures in Downey, CA (2026)
7 verified accessory structures rules for Downey, California, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Downey allows up to two ADUs plus one JADU on single-family lots in the R-1, R-2, R-3, R-3-O, and M-U zones under § 9414.06 and § 9414.08, with size capped at 850-1,000 square feet, four-foot side/rear setbacks, and a 16-foot height limit for detached units.
Downey Accessory Dwelling Unit Zoning Rules
Some RestrictionsDowney, CA, Municipal Code § 9414.06; § 9414.08(a)(1), (b)(1), (d)(1)
§ 9414.06. ZONING ALLOWANCE. Unless otherwise provided by preemptive State law or this Code, ADUs and JADUs shall be a permitted use in the following locations: (a) An ADU or JADU are allowed within the City's residential zones developed with an existing and proposed residential dwelling: R-1, R-2, R-3, R-3-O and M-U... (1) JADUs shall not be allowed in properties zoned for multifamily. § 9414....
ADU Impact Fees
Downey waives impact fees entirely for any ADU under 750 square feet, and for larger units caps the fee proportionally to the ADU's share of the primary dwelling's floor area, under Municipal Code § 9414.18(a).
Downey ADU Impact Fee Rules
Light RestrictionsDowney, CA, Municipal Code § 9414.18(a)
Impact Fees. (1) No impact fee is required for an ADU that is less than 750 square feet in size. For purposes of this subsection (a), "impact fee" means a "fee" under the Mitigation Fee Act (Govt. Code Section 66000(b)) and a fee under the Quimby Act (Govt. Code Section 66477). "Impact fee" here does not include any connection fee or capacity charge for water or sewer service. (2) Any impact fe...
ADU Owner Occupancy
Downey does not require an owner to live on-site for a standard detached or attached ADU, but a Junior ADU is different: the property owner must occupy one of the units as a legal domicile, secured by a recorded deed restriction before the JADU can pass final inspection.
Downey JADU Owner-Occupancy Rule
Some RestrictionsDowney, CA, Municipal Code § 9414.14(f)
Deed Restriction. Prior to final inspection of a building permit for an JADU, a deed restriction shall be recorded against the title of the property in the Los Angeles County Recorder's office and a copy filed with the Community Development Department. The form of the deed restriction will be provided by the City and must provide that: ... A JADU requires owner-occupancy within one of the units...
ADU Rental Restrictions
Downey bans short-term rentals of accessory dwelling units outright: § 9414.14(c) states no ADU may be rented for a term shorter than 30 days, a rule that applies to every ADU in the city regardless of when it was built or permitted.
Downey ADU 30-Day Minimum Rental Rule
Heavy RestrictionsDowney, CA, Municipal Code § 9414.14(c), (d)
(c) Rental Term. No ADU may be rented for a term that is shorter than 30 days. This prohibition applies regardless of when the ADU was constructed. (d) No Separate Conveyance. Except as required by Government Code Section 66341, ADUs may not be sold or separately conveyed.
Shed & Carport Rules
Downey lets homeowners build a one-story detached shed, playhouse or similar accessory structure without a building permit if its floor area stays at or under 120 square feet. Larger sheds need a permit, and every detached accessory building must still meet the placement rules in Municipal Code Section 9534.22.
Downey Backyard Shed Size & Setback Rules
Some RestrictionsDowney Municipal Code §§ 8999.28(b)(1)(i), 9534.22
One story detached accessory structures used as tool and storage sheds, playhouses and similar uses, provided the floor area does not exceed 120 square feet (11 m2). ... Detached accessory buildings shall be permitted in the required interior side and rear setback areas, subject to the following provisions: (a) No detached accessory building shall be within five feet of the front one-half (½) o...
Garage Conversions
Downey lets homeowners convert garages and other non-livable space into ADUs under § 9414.10(a)(3): on multifamily lots, up to 25% of existing units, but at least one, can come from converting garages, storage rooms, basements, or attics, while single-family conversions run through § 9414.08.
Downey Garage-to-ADU Conversion Rules
Some RestrictionsDowney, CA, Municipal Code § 9414.10(a)(3); § 9414.08(a)(1)
§ 9414.10(a)(3): Up to 25% of the existing number of units developed as part of the multifamily dwelling within the multifamily structure, but at least one ADU, can be converted from existing attached or detached areas that are not used as livable areas. These areas shall include, but are not limited to, storage rooms, boiler rooms, passageways, attics, basements, common areas, garages, or deta...
Tiny Homes
Downey lets residents build tiny houses under Appendix BB of the 2025 California Residential Code, adopted by reference as the "Downey Building Code" in Municipal Code Section 8993. A tiny house still needs a full building permit reviewed by the Building and Safety Division and must meet the appendix's reduced ceiling-height, egress, loft and stair standards rather than standard single-family dwelling requirements.
Downey Tiny House Building Code Rules
Some RestrictionsDowney, CA, Municipal Code § 8993
Except as provided herein, the 2025 Edition of the California Residential Code, (California Code of Regulations, Title 24, Part 2.5), based upon the 2024 International Residential Code, including Appendix BB (Tiny Houses), BF (Patio Covers), BG (Sound Transmission), and C1 (Swimming Pool Safety Act), is hereby adopted by reference as though fully set forth herein, and shall constitute and is he...
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County ordinances apply to unincorporated areas and may supplement Downey city rules.
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