ADU rules in Sacramento County

Since October 22, 2026 the county has no local ADU ordinance: Table 3.2 lists ADUs and JADUs ('Dwelling Unit, Accessory / Junior Accessory') as a permitted accessory use by right ('A') in the single-family (RD-1 to RD-10), multifamily (RM-2, RD-15 and up), commercial (BP, LC, GC) and mixed-use (NMC, CMC, CMZ) zones, and SZC 6.8.2.F says the county 'will review and process permits for accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs) in a manner consistent with GOV § 66323 and HCD Guidance.' The county's Zoning Code User Guide Appendix A allows a lot with a single-family home or halfplex 'potentially totaling three ADUs': one new detached ADU, one JADU, and one attached, attached-conversion or detached-conversion ADU. A multifamily lot may add two new detached ADUs (new projects) or, if developed by January 1, 2025, up to eight or its existing unit count, whichever is less, plus conversions of non-livable space. ADUs and JADUs are NOT permitted in the agricultural (AG), agricultural-residential (AR-1 to AR-10), urban reserve, interim agricultural reserve, recreation (RR, O, C-O) or industrial (MP, M-1, M-2) zones; outside the industrial zones the county allows up to two detached Agricultural Accessory Dwellings per lot instead, a separate use the code says is not an ADU (see caveats, including a possible conflict with state law).

Attached ADUs (additions) and conversions of existing space, including garages and accessory structures, are allowed alongside a detached ADU: Appendix A lets a single-family or halfplex lot add one new attached ADU, attached conversion ADU or detached conversion ADU besides the detached ADU and the JADU. A JADU of up to 500 sq ft must sit within the proposed or existing primary dwelling (an attached garage or storage area counts), needs at least an efficiency kitchen and a separate exterior entrance, plus an interior entry when it shares the home's bathroom; every ADU needs its own bathroom, a full kitchen and a separate exterior entrance. Multifamily lots may convert non-livable space (storage rooms, attics, basements, garages) into ADUs, up to 25 percent of the existing unit count or one unit, whichever is greater. None of this applies on AG, AR, recreation or industrial lots, where ADUs and JADUs are not permitted and the substitute Agricultural Accessory Dwellings must be detached from the main home.

Appendix A limits a new detached ADU to 1,200 sq ft and an attached new-construction ADU to the greater of 50 percent of the primary dwelling's habitable area, 850 sq ft for a studio or one-bedroom unit, or 1,000 sq ft with two or more bedrooms (the Gov. Code 66321(b)(2) floors). A conversion ADU is limited to the existing space plus up to 150 sq ft for ingress and egress (for example a stairwell); a JADU is limited to 500 sq ft within the home, with the same 150 sq ft allowance when converted from existing space; every ADU must be at least 150 sq ft, and an ADU may not exceed the primary dwelling's square footage, so a larger new house reclassifies the existing one as the ADU. Heights are measured to the peak: 16 ft for a detached ADU on a single-family or halfplex lot, 18 ft if within half a mile of a major transit stop or to match the main home's roof pitch (with documentation of both pitches), 25 ft or the primary dwelling's limit (if lower) for attached units, and 18 ft for detached units on multifamily lots; the number of stories is limited only by height. Side and rear setbacks are 4 ft, ADUs must stay out of recorded public easements, and a new ADU over 800 sq ft must meet the zone's front setback while one of 800 sq ft or less needs none. The former local extras (a 20-ft detached height with larger setbacks and discretionary two-story or deviation approvals) ended with the repeal: 'Requests for deviation from standards provided in this Appendix and/or CA GOV § 66310-66342 are prohibited.'

Neither the Zoning Code nor Appendix A requires the owner to live on a lot with an ADU, and Gov. Code 66315 bars owner-occupancy conditions for ADUs. JADUs are the exception only when they share a bathroom: Appendix A permits a JADU with shared bathroom facilities 'subject to property owner occupancy on the subject property, a recorded deed restriction, a separate exterior entrance from the primary dwelling, and an interior entry,' matching Gov. Code 66333(b) as amended by AB 1154, which also exempts government agencies, land trusts and housing organizations; a JADU with its own bathroom carries no owner-occupancy requirement. State law also requires every JADU to carry a recorded deed restriction against separate sale and on its size and attributes (66333(c)).

Appendix A requires 'One (1) parking space ... for new construction detached ADUs over 800 square feet in size accessory to single-family or halfplex developments,' and none for smaller detached ADUs or 'ADUs of any other type.' Even that space is not required within half a mile walking distance of public transit, in an architecturally and historically significant historic district, where on-street parking permits are required but not offered to the ADU occupant, within one block of a car share vehicle, or when a garage, carport or parking space is demolished or converted for the ADU; state law adds further exemptions (for example an ADU applied for together with a new home or multifamily building) that the county must honor (Gov. Code 66322(a)). No replacement parking is owed for a converted or demolished garage, carport or space, JADUs need none (66334(a)), and state law caps any requirement at one space per unit or per bedroom, whichever is less (66314(d)(10)).

ADUs and JADUs are a permitted accessory use by right ('A' in Table 3.2) in the zones where they are allowed, and Appendix A states that the county 'has no discretionary process for review of ADU applications and only imposes ministerial review through building permits for ADUs as is required by State law'; deviations from the standards are prohibited, and ADUs are exempt from Design Review (SZC 6.3.2.B.3). Permits go through Building Permits and Inspection, with Planning and Environmental Review checking zoning and with sewer or septic, water and fire district reviews as applicable; converting an existing accessory structure is a change of use that needs a building permit and code upgrades. State law requires a completeness decision within 15 business days and approval or denial within 60 days of a complete application without a hearing (Gov. Code 66317).

An ADU may be rented to a long-term tenant, but 'An ADU shall not be used for short-term rental/lodging purposes (30 days or less) unless it was legally permitted as an ADU prior to January 1, 2020,' and a JADU may never be a short-term rental (Appendix A.2.D; SZC 3.9.3.AA, which the repeal left in place). A qualifying pre-2020 ADU still needs a Short-Term Rental Permit, a business license and 12 percent transient occupancy tax registration, and the owner or a long-term renter must live on the property at least six months a year, with stays capped at 29 consecutive days and one rental party at a time; state law separately requires terms longer than 30 days for units created under Gov. Code 66323 (66323(e)) and for all JADUs (66333(g)). Long-term rentals fall under the Rental Housing Inspection Program: no rental dwelling unit may be occupied by a tenant until the annual Rental Housing Code Compliance fee ($16 per unit per year, billed on the county utility bill) is paid and owner information is filed (County Code 16.20.400-.410). An ADU cannot be sold separately except through the qualified-nonprofit path of Gov. Code 66341; the county has not adopted a Gov. Code 66342 ADU condominium ordinance.