These rules apply to UNINCORPORATED Sacramento County - communities like Arden-Arcade, Carmichael, Fair Oaks, Orangevale, Rio Linda, and Antelope - not the City of Sacramento, which has its own ADU program. The County allows one ADU plus one JADU on any single-family or halfplex lot (and ADUs on duplex/multifamily lots), with detached ADUs up to 1,200 sq ft approved ministerially under Zoning Code Section 5.4.5.B. The County also offers five free pre-approved Shelf Ready ADU plan sets, from a 460 sq ft studio to the 1,184 sq ft three-bedroom Model D Magnolia, usable only in unincorporated areas.
Zoning & Size Requirements [1][2]
Yes — unincorporated Sacramento 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.
| Where ADUs Are Allowed | All zoning districts where residential dwellings are permitted (AG, AR, RD-1 through RD-40, and multifamily zones) per Zoning Code 3.9.3.D and Table 5.11 |
| Max Size (Detached) | 1,200 sq ft new construction (no further increases per Table 5.11); conversions of existing permitted structures may add 150 sq ft for ingress/egress |
| Max Size (Attached) | 50% of the primary dwelling's habitable square footage, or 800 sq ft, whichever is greater |
| Max Size (JADU) | 500 sq ft within the primary dwelling (including attached garage), plus 150 sq ft for ingress/egress |
| Max Height | Detached: 16 ft to peak (18 ft within 1/2 mile of major transit or to match the primary roof pitch; 20 ft with 10 ft rear and 5 ft side setbacks); attached: 25 ft; single story for detached/attached ADUs |
| Max Units | Single-family/halfplex lot: 1 ADU + 1 JADU. Duplex/multifamily: up to 2 detached ADUs plus conversion ADUs up to 25% of existing units. Cannot be stacked with an SB 9 lot split |
Setback & Parking Requirements [1][2]
Unincorporated Sacramento County requires a rear setback of about 4 ft for a detached ADU, and one off-street parking space is required. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 4 ft (up to a 24-inch eave may project into the setback) |
| Side Setback | 4 ft interior; 12.5 ft street side on corner lots |
| Front Setback | 20 ft (an administrative deviation is possible where this would prevent an 800 sq ft ADU) |
| Parking Required | 1 space, waived within 1/2 mile of transit, in historic districts, for conversions, near car share, or where street permits are unavailable to the ADU; no replacement parking when a garage is converted |
| Owner Occupancy | Not required for ADUs. JADUs: the County table requires owner occupancy of the home or JADU, but state AB 1154 (Jan 2026) bars that for JADUs with their own bathroom - confirm current application with SacPlan |
| Min Lot Size | None - California law prohibits minimum lot sizes for ADUs and Table 5.11 imposes none |
Permit Process & Fees [3]
An ADU in unincorporated Sacramento County is approved ministerially (by-right) within 60-day state deadline from a complete application; SB 543 (Jan 2026) adds a 15-business-day completeness check. Shelf Ready plans skip structural plan check; permit fees are Valuation-based and site-specific - get a written estimate from Building Permits and Inspection (916-875-5296) before budgeting.
| Approval Process | Ministerial building-permit review - no hearing, no discretionary review. Apply via the County Citizen Access Portal (actonline.saccounty.gov); Building Permits and Inspection + SacPlan review |
| Review Timeline | 60-day state deadline from a complete application; SB 543 (Jan 2026) adds a 15-business-day completeness check. Shelf Ready plans skip structural plan check |
| Permit Fees | Valuation-based and site-specific - get a written estimate from Building Permits and Inspection (916-875-5296) before budgeting |
| Impact Fees | Waived for ADUs under 750 sq ft (state law); proportional above that. School fees exempt under 500 sq ft livable space per SB 543 |
| Plan Check | Standard for custom designs; Shelf Ready plan sets are pre-checked to the 2022 California codes - applicant supplies only a plot plan, PV plans (Models B/C/D), and a Hold Harmless Agreement |
| Pre-Approved Plans | Yes - the free Shelf Ready ADU Program (unincorporated county only): A1 Laurel 460 sq ft, A2 Willow 460 sq ft, B Redwood 870 sq ft, C Elderberry 1,000 sq ft, D Magnolia 1,184 sq ft (3BR) |
Get Free ADU Quotes in Sacramento County
Tell us about your project and we'll connect you with ADU builders serving Sacramento County. Free, no obligation — you choose who to work with.
🔒 Your info is secure. We share it only with contractors quoting your project. No spam, no obligation.
Construction Costs [4]
Building an ADU in unincorporated Sacramento County typically costs $150,000-$320,000 (regional market estimate; Shelf Ready plans cut design costs) ($180-$330 (market estimate) per sq ft); a garage conversion runs $90,000-$180,000 (market estimate).
Construction costs in unincorporated Sacramento County mirror the surrounding Inland Empire market. Rural parcels can cost more due to septic, well, access, and fire-hazard (WUI) requirements, so treat these as planning ranges and get local bids.
| Average Build Cost | $150,000-$320,000 (regional market estimate; Shelf Ready plans cut design costs) |
| Cost per Sq Ft | $180-$330 (market estimate) |
| Garage Conversion | $90,000-$180,000 (market estimate) |
| Prefab ADU (Installed) | $120,000-$260,000 (market estimate) |
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
Some links on this page are affiliate links. We may earn a commission at no extra cost to you. Learn more
Rental Income Potential [5]
| Avg Rent (1 Bedroom) | $1,500-$1,900/mo (Sacramento-area market) |
| Avg Rent (2 Bedroom) | $1,800-$2,400/mo |
| Short-Term Rental | County short-term rental rules apply - confirm with the County before planning an STR |
| Est. Annual ROI | 6-9% annual return (market estimate) |
Recent Law Changes
What's Changed Recently
- July 11, 2024: County amended Zoning Code 3.9.3.D and 5.4.5.B/Table 5.11 - the current ADU/JADU standards (multifamily allowances, height tiers, conversion rules)
- Late 2024: the free Shelf Ready ADU plan program launched (5 pre-approved detached models, 460-1,184 sq ft) with strong homeowner uptake through 2025
- Jan 1, 2026: SB 543 took effect - 15-business-day completeness review, livable-space definition, school-fee exemption under 500 sq ft, deemed-approved at 60 days
- Jan 1, 2026: AB 1154 limited JADU owner-occupancy requirements to JADUs sharing a bathroom with the main house
- June 11, 2026: County adopted Zoning Code Section 5.4.7 (SB 9 standards), which interact with ADU allowances
Tips for Building an ADU in Unincorporated Sacramento County
- Arden-Arcade, Carmichael, and Fair Oaks are unincorporated - County rules and the Shelf Ready plans apply there, not City of Sacramento rules
- The Shelf Ready Model D Magnolia (1,184 sq ft, 3BR) is the largest free pre-approved plan - Models B, C, and D require photovoltaic systems
- Keep the ADU under 750 sq ft to avoid impact fees entirely
- Confirm your parcel's jurisdiction first: if you are inside city limits (Sacramento, Citrus Heights, Folsom, Elk Grove), that city's rules apply instead
ADU Builders in Sacramento County
Looking for an ADU builder in Sacramento County? ADU projects need a contractor experienced with local zoning, the permit process, and utility connections — not every general contractor has built one. We match Sacramento County homeowners with experienced local ADU contractors who provide free, no-obligation quotes. Getting at least three bids typically saves 20-40% on the same scope.
Cities Within Sacramento 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.
- Sacramento County Zoning Code Ch. 5 (Table 5.11, Sec. 5.4.5.B) Planning Department — Accessed 2026-07-08
- Sacramento County Zoning Code Ch. 3 (Sec. 3.9.3.D) Planning Department — Accessed 2026-07-08
- Sacramento County - Shelf Ready ADU Plans Planning Department — Accessed 2026-07-08
- Angi - ADU Construction Cost Data Market Data — Accessed 2026-07-08
- HUD Fair Market Rents Government Data — Accessed 2026-07-08
- California ADU Handbook - HCD Government Data — Accessed 2026-07-08
Frequently Asked Questions
What are the ADU rules in unincorporated Sacramento County?
How much does an ADU permit cost in Sacramento County?
Do I need owner-occupancy for an ADU in Sacramento County?
Is my property in unincorporated Sacramento County or inside a city?
How many ADUs can I build in unincorporated Sacramento County?
Building in Unincorporated Sacramento County?
Get free, no-obligation quotes from ADU contractors who work in Sacramento County.
Get Free Quotes →