Local zoning · Contra Costa County

Contra Costa County — Land Use

Q: Can I build a duplex in Contra Costa County’s unincorporated areas?

Yes, in the D-1 Two‑Family Residential district, a detached two‑family dwelling (duplex) is permitted, and R‑6 uses also apply (§ 84-22.402). The lot must be at least 8,000 sq ft , front setback follows R‑6 ( 20 ft ), and you need two covered spaces per dwelling, each 9 ft by 19 ft (§ 84-22.602; § 84-22.1004; § 84-22.1202).

Q: What are the front setback requirements for multi-family and agricultural districts?

In M-29 (multi-family), the front setback is 25 ft (§ 84-26.1004). In A-2 (agricultural), the front setback is 25 ft , and the secondary frontage on a corner must be at least 20 ft (§ 84-38.1004).

Q: Are ADUs allowed on agricultural land in unincorporated Contra Costa County?

Yes. ADUs are allowed on lots in agricultural districts ( A‑2, A‑3, A‑4, A‑20, A‑40, A‑80 ) (§ 82-24.010(b)). Detached ADUs may be up to 1,200 sq ft in agricultural districts, with 4 ft side/rear setbacks for new detached units; many configurations are ministerially approvable if criteria are met (§ 82-24.006; § 82-24.012).

Q: What industrial uses are allowed without a land use permit, and which need one?

In L‑I (Light Industrial), light industrial uses not needing steam power and not dependent on extensive loading docks are generally allowed; uses that could create dust/smoke/fumes/noise/brilliant light require a land use permit with conditions (examples include asphalt plants, rendering, food processing, wineries, breweries) (§ 84-58.402). Uses from residential, commercial, agricultural, and forest recreation districts may be allowed by land use permit (§ 84-58.404(1)).

Q: Is cannabis allowed in unincorporated Contra Costa County?

Commercial cannabis activities can be allowed in R‑B and L‑I districts with a land use permit and compliance with Chapter 88‑28 (§ 84-52.404(16); § 84-58.404(2)). Confirm allowable license types and locations with the County. Verify with the jurisdiction.

Q: What hillside restrictions could limit my project?

Parcels with average slopes over 26% and/or significant ridgelines/hilltops cannot be graded without explicit authorization, and final slopes must not exceed the critical gradient and must protect safety and vegetation (§ 814-2.1002; § 88-11.822). Expect additional scrutiny regarding visual and environmental impacts.

Land Use under the Contra Costa County local zoning and planning code, with the controlling citations.

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Quick answer

In unincorporated Contra Costa County, land uses must match the mapped zoning district and comply with district standards (§ 84-2.002; § 82-2.004). Example setbacks: 20 ft in R‑6 (§ 84-4.1004) and 25 ft in M‑29 and A‑2 (§ 84-26.1004; § 84-38.1004). Detached ADUs are broadly allowed with 4 ft side/rear setbacks and up to 1,200 sq ft in agricultural districts (§ 82-24.010; § 82-24.012).

Last reviewed: July 25, 2026 · AI-generated analysis · General information, not legal advice · details

Compiled from Contra Costa County's adopted code with AI research tools and grounded in the sources cited below. Verify with Contra Costa County planning staff before relying on it.

Overview

In the unincorporated areas of Contra Costa County, what you can use land for is controlled by the County’s zoning ordinance in Title 8 and shown on the official zoning map. Each zoning district sets its own permitted uses, uses needing a land use permit, and basic site standards like setbacks. Some cross-cutting programs (e.g., hillside standards, agricultural preserves, and ADUs) further condition land uses in specific locations.

Land in unincorporated Contra Costa County must conform to the use rules of its mapped zoning district, and no structure or land may be used or altered without full compliance with the zoning ordinance and other applicable regulations (§ 84-2.002; § 82-2.004; § 82-28.606).

Use the County’s zoning map to identify your district, then confirm the applicable development standards and whether the proposal triggers design review, a land use permit, or other procedures.

How land use is organized (unincorporated areas)

Zoning map controls: The County adopts and maintains the “Zoning Map of Contra Costa County.” District boundaries and interpretation rules are codified, and the map is on file with the Community Development Department (§ 84-2.002). The ordinance applies to all private and public uses of land in the county’s unincorporated territory (§ 82-2.004).
Compliance is mandatory: Construction, location, extension, or change of use must fully comply with zoning; violations are enforceable and punishable as infractions (§ 82-28.606).
Agricultural preserves/Williamson Act: The Board may designate agricultural preserves; preserves are limited to land primarily used for commercial agriculture and must meet uniform standards (§ 810-2.202; § 810-2.402; § 810-2.414). Land conservation contracts must restrict uses to commercial agricultural and compatible uses allowable in an agricultural preserve district (§ 810-4.406).
Hillside and slope regulation: In hillside areas, the County imposes objectives and restrictions to protect terrain, visual quality, and safety (§ 814-2.204; § 814-2.206). Parcels with average slope over 26% and/or significant ridgelines/hilltops cannot be graded without specific authorization (§ 814-2.1002). Final slope gradients must assure stability and public safety and cannot exceed the critical gradient per engineering analysis (§ 88-11.822). See overlay districts.
ADUs across zones: Accessory dwelling units are broadly allowed in residential and agricultural districts with standardized siting and size limits, many approved ministerially (§ 82-24.006; § 82-24.010; § 82-24.012). For state context, see California ADU law.

District-by-district: allowed uses and key standards (unincorporated areas)

R-6 Single-Family Residential District

Purpose: Not found in source materials.
Typical permitted uses: Not found in source materials.
Key dimensional standards:
- Front setback: The R-6 district requires a 20 ft front setback; on a corner lot, the secondary frontage must be at least 15 ft (§ 84-4.1004).
Where it applies: Any parcel shown as R-6 on the County zoning map (§ 84-2.002). Verify with the jurisdiction.

D-1 Two-Family Residential District

Purpose: Two-family residential.
Typical permitted uses:
- Permitted: All uses designated for the R-6 district and one detached duplex (two-family dwelling) per lot (§ 84-22.402). Specific R-6 permitted uses are not included in the source materials.
- Land use permit (LUP): Any use in the D-1 district that requires a permit under the R-6 rules likewise requires a land use permit here (§ 84-22.404).
Key dimensional/parking standards:
- Minimum lot area: 8,000 sq ft (§ 84-22.602).
- Front setback: Same as R-6 — 20 ft (§ 84-22.1004; § 84-4.1004).
- Side yard: Same as R-10 (numerical standard not provided in the source) (§ 84-22.1002). Not found in source materials.
- Rear yard: Same as R-6 (numerical standard not provided in the source) (§ 84-22.1006). Not found in source materials.
- Parking: Two covered spaces per dwelling unit, each at least 9 ft x 19 ft (§ 84-22.1202). See also parking.
Where it applies: Any parcel mapped as D-1 (§ 84-2.002). Verify with the jurisdiction.

R-65 Single-Family Residential District

Purpose: Large-lot single-family neighborhood context (implied by district name; formal purpose not provided).
Typical permitted/conditional uses:
- Uses requiring a land use permit: “All the uses designated for the R-6 district” with certain deletions (large greenhouses; hospitals/eleemosynary/philanthropic institutions/convalescent homes) and horse riding academies/instruction subject to standards (§ 84-18.404). What is outright permitted in R-65 is not in the source.
Key dimensional standards: Not found in source materials.
Where it applies: Parcels mapped R-65 (§ 84-2.002). Verify with the jurisdiction.

M-29 Multiple Family Residential District

Purpose: Allow multi-family while providing compatibility with nearby single-family zoning (§ 84-26.204).
Typical permitted uses: Not found in source materials (chapter states uses exist, but the specific list is not included here) (§ 84-26.202).
Key dimensional standards:
- Front setback: 25 ft (§ 84-26.1004).
Where it applies: Parcels mapped M-29 (§ 84-2.002). Verify with the jurisdiction.

R-B Retail Business District

Purpose: Retail and related commercial services (inferred from name; formal purpose not provided).
Uses requiring a land use permit (examples):
- Lumber yard; cabinet or sheet-metal shop; animal hospital; commercial or hobby dog kennels; auto garage with body/paint; building contractor’s yard; certain retail with activities outdoors; single-room occupancy facilities (if compliant with Chapter 82-48); and specified light “manufacturing research” in existing buildings that meets performance standards (no smoke/odors/dust/fumes/heat/glare/vibration; noise ≤70 dB at boundaries; indoor ops; screened storage) (§ 84-52.404).
- Commercial cannabis activities if compliant with Chapter 88-28 (§ 84-52.404(16)).
- Special access control: Where a road of right-of-way ≤55 ft forms the boundary with a residential district, access to/from that road requires a land use permit; the decision turns on traffic and neighborhood effects (§ 84-52.404(13)).
Key dimensional standards: Not found in source materials.
Where it applies: Parcels mapped R-B (§ 84-2.002). Verify with the jurisdiction.

A-2 Agricultural District

Purpose: Agricultural lands (formal purpose not provided).
Typical permitted uses: Not found in source materials.
Key dimensional standards:
- Front setback: 25 ft; on a corner, secondary frontage at least 20 ft (§ 84-38.1004).
ADUs: ADUs are allowed in agricultural districts (size and siting rules below) (§ 82-24.010(b); § 82-24.012).
Where it applies: Parcels mapped A-2 (§ 84-2.002). Verify with the jurisdiction.

L-I Light Industrial District

Purpose: Accommodate light industrial uses; Chapter 84-63 may also apply (§ 84-58.202).
Typical permitted/conditional uses:
- Permitted: Light industrial uses not needing steam power on-site and not dependent on extensive loading docks. If a use emits dust/smoke/fumes/noise/brilliant light or otherwise risks a nuisance, it may be established only with a land use permit and conditions; examples include hot-mix asphalt plants, rendering, food processing, tanneries, wineries, breweries, and similar (§ 84-58.402).
- Land use permit: Uses from residential, retail business, neighborhood business, general commercial, agricultural, and forestry recreation districts may be allowed with a land use permit (§ 84-58.404(1)).
- Cannabis: Commercial cannabis activities may be allowed with a land use permit if compliant with Chapter 88-28 (§ 84-58.404(2)).
Key dimensional standards:
- Minimum lot area: 7,500 sq ft (§ 84-58.602).
Where it applies: Parcels mapped L-I (§ 84-2.002). Verify with the jurisdiction.

W-3 Controlled Heavy Industrial District

Purpose: Heavy industrial with controls; Chapter 84-63 may apply (§ 84-60.202).
Typical permitted uses: Not found in source materials (chapter states uses exist, but the specific list is not included here) (§ 84-60.202).
Key dimensional standards: Not found in source materials.
Where it applies: Parcels mapped W-3 (§ 84-2.002). Verify with the jurisdiction.

C (Commercial) Districts — Development Plans

Development plan prerequisite: In any C commercial district, no development is lawful until a development plan is submitted and approved per Article 84-50.16 (§ 84-54.1602). Coordinate this early with design review.
Permitted uses/dimensions: Not found in source materials.
Where it applies: Parcels mapped in any C district (§ 84-2.002). Verify with the jurisdiction.

Accessory Dwelling Units (ADUs) — where allowed and core limits (unincorporated areas)

Where allowed: On lots in single‑family districts (R-6, R-7, R-10, R-12, R-15, R-20, R-40, R-65, R-100), water recreation (F-1), planned unit (P-1 for residential uses), multi‑family (M-6, M-9, M-12, M-17, M-29), and agricultural (A-2, A-3, A-4, A-20, A-40, A-80) (§ 82-24.010).
Ministerial approvals: Specific “by-right” ADUs/JADUs are approved ministerially when meeting enumerated criteria (e.g., internal conversions; one detached ADU up to 800 sq ft with 4-ft side/rear setbacks; multi-family conversions/additions) (§ 82-24.006(b)).
Size limits (§ 82-24.012(a)):
- Detached: Generally up to 1,000 sq ft; up to 1,200 sq ft on lots ≥12,000 sq ft; up to 1,200 sq ft in agricultural districts; Kensington (-K) has lower caps.
- Attached: Generally up to 1,000 sq ft; up to 1,200 sq ft on lots ≥12,000 sq ft or in agricultural districts; capped at 50% of the primary dwelling’s living area unless needed to reach 850–1,000 sq ft minimums.
Setbacks and height: Side/rear setbacks for new detached ADUs are 4 ft; internal conversions and rebuilds in the same footprint need no new setback. Height is constrained as specified in Government Code § 66321(b)(4) where applicable (§ 82-24.012(h)).
Parking: One additional off‑street space is required unless exceptions apply; tandem or within setbacks is generally allowed unless infeasible for safety/topography. No replacement parking is required if a garage/carport is converted/demolished for an ADU (§ 82-24.012(i)). See parking.
Other basics: Independent exterior access and complete living facilities are required; permanent foundations and compliant water/sewer are required (§ 82-24.012(b)–(e)). Building standards are in the California Building Standards Code.

Selected land-use rules at a glance (unincorporated areas)

District/Topic	Core rule or typical trigger	Key dimensional standard	Code Reference
Zoning applicability	Zoning applies to all private/public land uses in unincorporated county	—	§ 82-2.004
Zoning map	Map adopted; governs boundaries and interpretations	—	§ 84-2.002
Compliance	No construction/change of use without full compliance	—	§ 82-28.606
R-6	Single-family area; specific permitted uses not provided here	Front setback: 20 ft (15 ft on secondary corner frontage)	§ 84-4.1004
D-1	Duplex permitted; R-6 uses carry over	Min lot area: 8,000 sq ft; front setback: 20 ft; 2 covered spaces/unit (9x19 ft)	§ 84-22.402; § 84-22.602; § 84-22.1004; § 84-22.1202
R-65	LUPs for R-6-type uses with deletions; equestrian uses by standards	—	§ 84-18.404
M-29	Multi-family intent; detailed use list not provided here	Front setback: 25 ft	§ 84-26.204; § 84-26.1004
R-B	Retail/business; many uses need a land use permit	Performance standards for “manufacturing research”; cannabis allowed with LUP	§ 84-52.404
A-2	Agricultural	Front setback: 25 ft (20 ft secondary corner frontage)	§ 84-38.1004
L-I	Light industrial permitted; some nuisance-prone uses require LUP	Min lot area: 7,500 sq ft; cannabis allowed with LUP	§ 84-58.202; § 84-58.402; § 84-58.404; § 84-58.602
W-3	Controlled heavy industrial (uses listed in chapter; not provided here)	—	§ 84-60.202
C districts	Development plan required before any development	—	§ 84-54.1602
Hillside/grading	Authorization needed for >26% slope or significant ridgelines	Final slopes may not exceed critical gradient	§ 814-2.1002; § 88-11.822
Ag preserves/Williamson Act	Preserves limited to commercial ag; LCC contracts restrict to ag/compatible	—	§ 810-2.202; § 810-2.414; § 810-4.406

R-B land uses requiring a land use permit (examples)

Lumber yards; contractor yards; auto garages with body/paint; cabinet/sheet-metal shops; animal hospitals; commercial/hobby kennels; and retail with some activities outdoors (§ 84-52.404).
Manufacturing research in existing enclosed buildings if strict performance standards are met (no smoke/odors/dust/fumes/heat/glare/vibration; noise ≤70 dB at property lines; indoor operations; screened storage) (§ 84-52.404(14)).
Single room occupancy facilities (if compliant with Chapter 82-48) and commercial cannabis activities compliant with Chapter 88-28 (§ 84-52.404(15), (16)).
Where a ≤55‑ft right‑of‑way separates R‑B from a residential district, driveway access to that road requires a permit based on traffic/pedestrian safety considerations (§ 84-52.404(13)).

Checklist (unincorporated areas)

Identify your parcel’s zoning on the County’s zoning map and confirm it is in unincorporated Contra Costa County (§ 84-2.002; § 82-2.004).
Confirm the use is permitted or determine if a land use permit is required in your district (e.g., R‑B, L‑I) (§ 84-52.404; § 84-58.402; § 84-58.404).
Verify basic dimensional standards (e.g., R‑6 20 ft setback; M‑29 25 ft; A‑2 25 ft) and any cross-referenced standards (§ 84-4.1004; § 84-26.1004; § 84-38.1004).
For commercial districts, prepare and obtain approval of a development plan before any development (§ 84-54.1602).
If proposing an ADU/JADU, check allowed locations, sizes, setbacks, height, and parking; verify eligibility for ministerial approval (§ 82-24.006; § 82-24.010; § 82-24.012).
If in a hillside/ridgeline or steep-slope area, secure grading authorization and meet slope-stability standards (§ 814-2.1002; § 88-11.822).
If the land is under a Williamson Act contract or in an agricultural preserve, confirm use restrictions to agricultural/compatible uses (§ 810-2.414; § 810-4.406).
Coordinate on any required design review and verify any applicable overlay districts.

Risks & Ambiguities

Issue	Why it matters	What to verify
Missing permitted-use lists in several districts (e.g., R‑6, M‑29, W‑3)	You could assume a use is allowed when it is not	Confirm with the Community Development Department; Not found in source materials
Cross-referenced standards (e.g., D‑1 side/rear yards via R‑10/R‑6)	Numerical yard standards aren’t all present here	Obtain the current R‑10/R‑6 yard standards from the County
R‑B access control on narrow rights‑of‑way	Driveway permitting can affect site design and feasibility	Whether the adjacent ROW is ≤55 ft and whether a permit is needed (§ 84-52.404(13))
Industrial “nuisance‑prone” uses in L‑I	Might need a land use permit with conditions to prevent nuisance	Whether your process triggers the LUP proviso in § 84-58.402
Cannabis activities	Allowed only where expressly provided and subject to Chapter 88‑28	Whether the site/district and business type qualify (§ 84-52.404(16); § 84-58.404(2))
Hillside grading thresholds	Work on steep slopes or near ridgelines may be disallowed without authorization	Slope analysis (>26% average) and presence of significant ridgelines/hilltops (§ 814-2.1002)
Agricultural preserve/contracted lands	Use is limited to ag/compatible; non‑ag uses may be prohibited	Existence of a preserve or land conservation contract and its terms (§ 810-2.414; § 810-4.406)

Plain-English Summary

If your property is in unincorporated Contra Costa County, start with the zoning map to see your district—then check whether your intended use is permitted or needs a land use permit and what setbacks or lot sizes apply. Residential areas like R‑6 have a 20‑ft front setback; multi‑family M‑29 and agricultural A‑2 require 25 ft in front. Commercial districts need an approved development plan before any development. ADUs are widely allowed across residential and agricultural zones with standard size and 4‑ft side/rear setbacks for detached units.

Information Gaps

R‑6, M‑29, and W‑3 permitted use lists: Not found in source materials.
R‑10 side yard and R‑6 rear yard metrics (cross‑referenced by D‑1): Not found in source materials.
Purpose statements for R‑6, R‑65, R‑B, A‑2, L‑I, W‑3, and detailed C district use lists: Not found in source materials.
Chapter 84‑63 additional industrial regulations: Not found in source materials.

Source References

§ 82-2.004 (Applicability to unincorporated territory)
§ 82-28.606 (Compliance and enforcement)
§ 82-1.032 (Definitions; “land within the county,” “nonurban uses”)
§ 84-2.002 (Zoning map adopted; interpretation)
§ 84-4.1004 (R‑6 front setback)
§ 84-18.404 (R‑65 uses requiring land use permit)
§ 84-22.202; § 84-22.402; § 84-22.404; § 84-22.602; § 84-22.1002; § 84-22.1004; § 84-22.1006; § 84-22.1202 (D‑1 standards and uses)
§ 84-26.202; § 84-26.204; § 84-26.1004 (M‑29 purpose and front setback)
§ 84-38.1004 (A‑2 front setback)
§ 84-52.404 (R‑B uses requiring land use permit; cannabis)
§ 84-54.1602 (C district development plan requirement)
§ 84-58.202; § 84-58.402; § 84-58.404; § 84-58.602 (L‑I uses and lot area; cannabis)
§ 84-60.202 (W‑3 general provisions)
§ 814-2.204; § 814-2.206; § 814-2.1002 (Hillside findings/objectives and grading restriction)
§ 88-11.822 (Final slope gradient standards)
§ 810-2.202; § 810-2.402; § 810-2.414 (Agricultural preserves; standards; land use restriction)
§ 810-4.402; § 810-4.406 (Land conservation contracts; land use restriction)
§ 82-24.004; § 82-24.006; § 82-24.010; § 82-24.012 (ADU definitions, ministerial approvals, locations, and development standards)

Also see: Contra Costa County zoning & planning overview, Zoning, Development Standards, Parking, Design Review, Overlay Districts, California Building Standards Code, California ADU law.

Sources

Source passages

Contra Costa County Zoning Code (§ 82-1.032) Medium relevance
Contra Costa County Zoning Code (§ 810-4.402) Medium relevance
Contra Costa County Zoning Code (§ 84-26.1004) Medium relevance
Contra Costa County Zoning Code (§ 88-11.822) Medium relevance
Contra Costa County Zoning Code (§ 84-52.404) Medium relevance
Contra Costa County Zoning Code (§ 84-54.1602) Medium relevance
Contra Costa County Zoning Code (§ 82-24.010) Medium relevance
Contra Costa County Zoning Code (§ 810-4.406) Medium relevance
Contra Costa County Zoning Code (§ 82-28.606) Medium relevance
Contra Costa County Zoning Code (§ 814-2.204) Medium relevance
Contra Costa County Zoning Code (§ 84-58.202) Medium relevance
Contra Costa County Zoning Code (§ 82-24.004) Medium relevance
Contra Costa County Zoning Code (§ 84-18.404) Medium relevance
Contra Costa County Zoning Code (§ 84-4.1004) Medium relevance
Contra Costa County Zoning Code (§ 84-22.202) Medium relevance
Contra Costa County Zoning Code (§ 814-2.1002) Medium relevance

Cited sections

§ 82-2.004 (Applicability to unincorporated territory) (§ 82-2.004)
§ 82-28.606 (Compliance and enforcement) (§ 82-28.606)
§ 82-1.032 (Definitions; “land within the county,” “nonurban uses”) (§ 82-1.032)
§ 84-2.002 (Zoning map adopted; interpretation) (§ 84-2.002)
§ 84-4.1004 (R‑6 front setback) (§ 84-4.1004)
§ 84-18.404 (R‑65 uses requiring land use permit) (§ 84-18.404)
§ 84-22.202; § 84-22.402; § 84-22.404; § 84-22.602; § 84-22.1002; § 84-22.1004; § 84-22.1006; § 84-22.1202 (D‑1 standards and uses) (§ 84-22.202)
§ 84-26.202; § 84-26.204; § 84-26.1004 (M‑29 purpose and front setback) (§ 84-26.202)
§ 84-38.1004 (A‑2 front setback) (§ 84-38.1004)
§ 84-52.404 (R‑B uses requiring land use permit; cannabis) (§ 84-52.404)
§ 84-54.1602 (C district development plan requirement) (§ 84-54.1602)
§ 84-58.202; § 84-58.402; § 84-58.404; § 84-58.602 (L‑I uses and lot area; cannabis) (§ 84-58.202)
§ 84-60.202 (W‑3 general provisions) (§ 84-60.202)
§ 814-2.204; § 814-2.206; § 814-2.1002 (Hillside findings/objectives and grading restriction) (§ 814-2.204)
§ 88-11.822 (Final slope gradient standards) (§ 88-11.822)
§ 810-2.202; § 810-2.402; § 810-2.414 (Agricultural preserves; standards; land use restriction) (§ 810-2.202)
§ 810-4.402; § 810-4.406 (Land conservation contracts; land use restriction) (§ 810-4.402)
§ 82-24.004; § 82-24.006; § 82-24.010; § 82-24.012 (ADU definitions, ministerial approvals, locations, and development standards) (§ 82-24.004)

Official Contra Costa County code library

Frequently asked questions

What uses are allowed in the R-6 single-family district in unincorporated Contra Costa County?

The source materials here include the R‑6 front setback but not the full permitted-use list. You must confirm permitted and conditionally permitted uses with the County. Known standard: front setback 20 ft (15 ft secondary frontage on corners) (§ 84-4.1004). Verify with the jurisdiction.

Can I build a duplex in Contra Costa County’s unincorporated areas?

Yes, in the D-1 Two‑Family Residential district, a detached two‑family dwelling (duplex) is permitted, and R‑6 uses also apply (§ 84-22.402). The lot must be at least 8,000 sq ft, front setback follows R‑6 (20 ft), and you need two covered spaces per dwelling, each 9 ft by 19 ft (§ 84-22.602; § 84-22.1004; § 84-22.1202).

What are the front setback requirements for multi-family and agricultural districts?

In M-29 (multi-family), the front setback is 25 ft (§ 84-26.1004). In A-2 (agricultural), the front setback is 25 ft, and the secondary frontage on a corner must be at least 20 ft (§ 84-38.1004).

Do commercial projects in Contra Costa County’s unincorporated areas need a development plan?

Yes. In any C commercial district, no development is lawful until a development plan is submitted and approved under Article 84‑50.16 (§ 84-54.1602). Coordinate early with County staff and design review.

Are ADUs allowed on agricultural land in unincorporated Contra Costa County?

Yes. ADUs are allowed on lots in agricultural districts (A‑2, A‑3, A‑4, A‑20, A‑40, A‑80) (§ 82-24.010(b)). Detached ADUs may be up to 1,200 sq ft in agricultural districts, with 4 ft side/rear setbacks for new detached units; many configurations are ministerially approvable if criteria are met (§ 82-24.006; § 82-24.012).

What industrial uses are allowed without a land use permit, and which need one?

In L‑I (Light Industrial), light industrial uses not needing steam power and not dependent on extensive loading docks are generally allowed; uses that could create dust/smoke/fumes/noise/brilliant light require a land use permit with conditions (examples include asphalt plants, rendering, food processing, wineries, breweries) (§ 84-58.402). Uses from residential, commercial, agricultural, and forest recreation districts may be allowed by land use permit (§ 84-58.404(1)).

Is cannabis allowed in unincorporated Contra Costa County?

Commercial cannabis activities can be allowed in R‑B and L‑I districts with a land use permit and compliance with Chapter 88‑28 (§ 84-52.404(16); § 84-58.404(2)). Confirm allowable license types and locations with the County. Verify with the jurisdiction.

What hillside restrictions could limit my project?

Parcels with average slopes over 26% and/or significant ridgelines/hilltops cannot be graded without explicit authorization, and final slopes must not exceed the critical gradient and must protect safety and vegetation (§ 814-2.1002; § 88-11.822). Expect additional scrutiny regarding visual and environmental impacts.

What happens if I use land in violation of zoning in unincorporated Contra Costa County?

Violations of the zoning ordinance or permit conditions constitute an infraction punishable under Government Code § 25132, and the Board may take action to prevent or remedy violations (§ 82-28.606).

How do agricultural preserves and Williamson Act contracts affect land use?

The Board can designate agricultural preserves, which must consist of land primarily used for commercial agriculture (§ 810-2.202; § 810-2.414). Land conservation contracts require the landowner to restrict uses to commercial agricultural and compatible uses as allowed in an agricultural preserve district (§ 810-4.406).

General information, not legal advice.

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