Add an ADU to your home in unincorporated Sacramento County

LotUpside is a one-stop ADU company for homes in unincorporated Sacramento County: we check your lot free against the county's rules, then match you with licensed designers and builders and coordinate the project with them.

Check your lot · free

What the unincorporated Sacramento County rules allow on your lot: setbacks, the biggest unit that fits, fees.

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Shape it in live 3D: size, rooms, roof and finishes, with an estimate priced for unincorporated Sacramento County.

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ADU rules at a glance

Largest detached ADULocal rule: 1,200 sq ftSacramento County Zoning Code 5.4.5.B, Table 5.11, footnote 5
State law allows at leastState law: 800 sq ft with 4 ft side and rear setbacksCal. Gov. Code 66321(b)(3) and 66323(a)(2)
Detached ADU heightLocal rule: 16 ft, one story (20 ft with 10 ft rear and 5 ft side setbacks)Sacramento County Zoning Code 5.4.5.B, Table 5.11 and footnote 8
Side and rear setbackLocal rule: 4 ftSacramento County Zoning Code 5.4.5.B, Table 5.11 (Setbacks)
Front setbackLocal rule: 20 ft (12.5 ft on a corner lot's street side)Sacramento County Zoning Code 5.4.5.B, Table 5.11 (Setbacks) and footnote 12
ADUs per single-family lotLocal rule: 2 ADUs + 1 junior ADUSacramento County ADU and JADU guide (V8, 2025), Table 1, p. 2
No impact fees up toState law: 750 sq ftCal. Gov. Code 66311.5(c)(1)
School feesState law: None under 500 sq ftCal. Gov. Code 66311.5(c)(3) and Ed. Code 17620(a)(1)(C)
Parking for the ADULocal rule: 1 space; none for a detached ADU of 800 sq ft or less or within 1/2 mile of transitSacramento County ADU and JADU guide (V8, 2025), Table 1 (Minimum Parking), p. 4
Replacing garage parking lost to an ADULocal rule: Not requiredSacramento County Zoning Code 5.4.5.B, Table 5.11 (Conversion of Covered Parking)
Owner must live on siteState law: Not for an ADU; for a junior ADU only if it shares the house's bathroomCal. Gov. Code 66315 and 66333(b), as amended by AB 1154 (2025)
Permit decision deadlineState law: 60 days from a complete applicationCal. Gov. Code 66317(a)(3)
County Shelf Ready ADU plansLocal rule: Free plan sets, 460 to 1,184 sq ftSacramento County Building Permits and Inspection, Shelf Ready ADU Program
Lots on septicLocal rule: County EMD reviews the plan; it may ask for a perc test from the last 5 yearsSacramento County EMD Liquid Waste Program; Cal. Gov. Code 66323(f)
County planning deskLocal rule: sacplan@saccounty.govSacramento County Planning and Environmental Review, Division Directory

Last verified 2026-10-15. Rules change; the Sacramento County planning desk has the final word.

What's different in unincorporated Sacramento County

One set of standards, and no rule that the ADU sit behind the house

Wherever the County allows a home, a new detached ADU follows one table: 20 ft from the front lot line, 12.5 ft from a corner lot's side street and 4 ft from the side and rear lot lines, with no rule that it sit behind the house. Closer than 5 ft to a lot line, fire and building reviewers may ask for fire-rated walls. Special Planning Areas, Neighborhood Preservation Areas and Planned Developments set their own front and corner setbacks.

Sacramento County Zoning Code 5.4.5.B, Table 5.11 and footnotes 9 and 12

Up to three units on a single-family lot

The County's ADU guide allows up to 3 units on a single-family or halfplex lot: 1 new detached ADU, 1 junior ADU, and 1 more ADU that is attached new construction or a conversion of existing space. The Zoning Code still prints 1 ADU and 1 junior ADU, but the County follows state law where the two conflict, and Gov. Code 66323(a) on its own allows a converted ADU, a junior ADU and a new detached ADU of up to 800 sq ft on one lot.

Sacramento County ADU and JADU guide (V8, 2025), Table 1, p. 2

Free County Shelf Ready ADU plans

Homeowners in unincorporated areas can use the County's free Shelf Ready plan sets for a detached ADU: a 460 sq ft studio or 1 bedroom, an 870 sq ft 2 bedroom, a 1,000 sq ft 2 bedroom and a 1,184 sq ft 3 bedroom. Building permit fees still apply, the plans are fixed apart from the built-in options and added electrical receptacles, lights and switches, and the local fire district reviews them separately. LotUpside's report doesn't price these plans yet; its options are custom and factory-built units.

Sacramento County Building Permits and Inspection, Shelf Ready ADU Program; County ADU guide (V8, 2025), p. 8

County fee programs exempt more than state law

State law bars impact fees on an ADU of 750 sq ft or less. The County's Parks, Library and Sacramento Metro Fire fee programs go further: ADUs of 850 sq ft or less, and multi-bedroom ADUs of 1,000 sq ft or less, are exempt, and larger ones pay at most a share in proportion to the house. Other County impact fees can apply above 750 sq ft, and each school district sets its own fee.

Sacramento County Parks, Library and Metro Fire development impact fee schedules (effective March 2, 2026)

Estimated costs and rents in unincorporated Sacramento County

Type	Est. all-in cost	Est. rent
Garage conversion	$196-$319 per sq ft of garage (about $78,000-$127,000 for a 400 sq ft garage)	$1,300-$1,750/mo
Junior ADU (inside the house)	$45,000-$80,000	$1,175-$1,425/mo
Detached 2 bedroom	$193,000-$289,000	$1,925-$2,375/mo
Detached 3 bedroom	$224,000-$341,000	$2,425-$2,975/mo

Estimates for a first conversation, not bids or appraisals. Source: LotUpside price book sac-2026-10.

How we work in unincorporated Sacramento County

1
Free lot check
A 12-check property screening from public records: what fits on your lot and what it adds.
2
Get matched with a licensed designer
Ask for a free consult and we look for a licensed designer for your plans and permit.
3
Get matched with a licensed builder
The builder holds the construction contract; we coordinate the project with them.

Licensed partners design and build, and the builder holds the construction contract. Partners are signed in some areas so far. All figures are estimates, not bids.

What our check reads in unincorporated Sacramento County

Rules from Sacramento County ADU standards (Zoning Code 5.4.5.B); zoning from the Sacramento County zoning map, CA Gov. Code 66314. Plus county parcel and assessor maps, CAL FIRE fire zones, FEMA flood maps, the California Geological Survey, the USDA soil survey, USGS elevation and Microsoft building outlines.

The report applies the 20 ft front and 4 ft side and rear setbacks; it does not apply the 12.5 ft corner street-side setback.

unincorporated Sacramento County ADU questions answered

Floor plans to start from

Measured ADU layouts you can edit and download as CAD files, then check against the unincorporated Sacramento County rules above.

Ready to build in unincorporated Sacramento County?

We'll match you with a licensed designer and builder in your area and coordinate the project. Free consult, no obligation.

Want to build it?

We'll match you with a licensed designer and builder in your area and coordinate the project. Free consult, no obligation.

Licensed partner designers and builders do the design and construction, and the builder holds the construction contract. Partners are signed in some areas so far; elsewhere we'll tell you plainly what we can do.

unincorporated Sacramento County ADU questions

Is my home in unincorporated Sacramento County?

It is if your lot is outside every city's limits, which takes in communities such as Carmichael, Fair Oaks, Orangevale, Arden-Arcade, North Highlands and Rio Linda, even when the mailing address says Sacramento. The County's planning FAQ and ADU guide point you to the County's online map to confirm, and LotUpside's free lot check reads the jurisdiction from the County's parcel records.

How many ADUs can I have on my lot in unincorporated Sacramento County?

Up to two ADUs and one junior ADU on a single-family or halfplex lot: one new detached ADU, one junior ADU inside the house, and one attached or converted ADU, according to the County's ADU guide (V8, Table 1). The Zoning Code table still says one of each, but the County's interim state-law guidance says it follows state law where the code conflicts with it.

What fees does an ADU pay in unincorporated Sacramento County?

State law bars impact fees on an ADU of 750 sq ft or less (Gov. Code 66311.5), and the County's Parks, Library and Metro Fire fee schedules exempt ADUs up to 850 sq ft, or 1,000 sq ft with two or more bedrooms. School fees are set by each district: San Juan Unified charges $5.38 per sq ft but excludes ADUs under 750 sq ft, and Twin Rivers Unified charges $5.38 per sq ft on ADUs of 500 sq ft or more, per their 2026 developer fee pages. Every ADU also pays building permit fees, as the County's ADU guide notes.

Can I rent out my ADU short term in unincorporated Sacramento County?

Not for stays of 30 days or less unless the ADU was legally permitted before January 1, 2020, and never for a junior ADU, under County Zoning Code 3.9.3.D. Longer rentals are allowed, and state law sets no owner-occupancy rule for an ADU (Gov. Code 66315).

Does the 20 ft front setback apply to a small detached ADU?

Not always: state law has the County approve a new detached ADU of up to 800 sq ft with 4 ft side and rear setbacks without local standards such as a front setback (Gov. Code 66323), and the County Zoning Code lets the Planning Director ease the front setback when it would block an 800 sq ft ADU (Table 5.11, footnote 6). A larger ADU generally keeps the County's 20 ft front setback, or the one in its area plan, unless a Special Development Permit deviation is approved (Table 5.11, footnote 6).

What's free, and what's in the $49 full report?

The free check gives the verdict from a 12-check property screening, your best move with the value it adds, the monthly rent and the cash you put in. The full report adds every option ranked, cost vs value ranges, concept floor layouts and site plan drafts, and every check with its sources. It is a one-time payment per property.

Is this a permit, or a plan I can build from?

Neither. It is a screening from public records, not professional advice, and not a survey, soils report, appraisal, loan offer or permit; every number is an estimate. A licensed designer confirms the final plan, and your city or county gives final approval.