Local jurisdiction · San Bernardino County
Ontario Zoning, Planning & Building Codes
What you can build in Ontario depends on its local zoning and planning code, layered on the California Building Standards Code. Ask GoCodebook about any Ontario address.
Key points
Last reviewed: July 4, 2026
Overview
Ontario's land-use law is consolidated in the city Development Code (the locally adopted zoning and land‑use regulations), which is organized into chapters and divisions that implement The Ontario Plan (the city's General Plan) and the Zoning Map. The Development Code establishes base and overlay zoning districts, supplemental use rules, district development standards, procedures for permits and appeals, and integration with specific plans and the Airport Land Use Compatibility Plan. § 1.01.025
This page explains how to read Ontario's code, the city's actual zoning families (residential, mixed‑use, commercial, industrial, open‑space and specialized districts), the high‑level development standards you will see on most projects (setbacks, height/FAR, lot coverage, parking), how design and discretionary review fit into the permits path, where specific plans and overlays change the rules, and how state housing laws (ADUs, Two‑Unit Projects / SB 9–style urban lot splits, ministerial approvals, and related limits) are implemented in the code. Key provisions are cited to the exact local section so you can verify details in the Development Code. § 5.01.005
Note: the rest of this page links to topic pages for quick navigation — the first time each topic is mentioned it is hyperlinked for convenience: Ontario's zoning, the city's development standards, parking, design review, overlay districts, ADUs, the California Building Standards Code, and California housing rules summarised at California housing laws and California ADU law.
How Ontario's code is organized
The city labels the document the Ontario Development Code; the table of contents shows Chapter/Division and section structure (Chapters 1–8 with Divisions for Administration, Zoning, Development Standards, etc.). The local Title/Title‑equivalent is the Development Code and the formal enactment and cross‑references to The Ontario Plan (General Plan) are in § 1.01.000–1.01.035. § 1.01.000 § 1.01.025
Procedure and who decides: Application filing, review timetables, and the "Review Matrix" that assigns ministerial vs discretionary roles are in Division 2 (Application Filing and Processing) and the ministerial/discretionary permit Divisions 4.02 (Discretionary Permits and Actions) and 4.03 (Ministerial/Administrative). See the Review Matrix and Development Plan triggers in § 2.02.015 and the ministerial/administrative permit rules in § 4.03.000–4.03.005. § 2.02.015 § 4.03.000
Where uses and rules live: Allowed uses are organized in the Land Use Matrix (Table 5.02‑1) and the supplemental use rules and detailed standards are in Division 5.03; district definitions and the Zoning Map authority are in Division 5.01; and development & subdivision standards (setbacks, heights, parking tables, landscaping, walls, etc.) are in Chapter 6.0 (Division 6.01–6.08). § 5.02.010 § 5.03.000 § 6.01.010
Practical navigation: start at Division 5.01 to find what base zoning district applies to your parcel and the Zoning Map (§ 5.01.015), then consult Table 5.02‑1 for allowed uses (§ 5.02.010), and then go to Chapter 6.0 for the numerical development standards that govern setbacks, lot coverage, parking (Division 6.03) and design standards (Division 6.01). § 5.01.015 § 5.02.010 § 6.03
Zoning district families (city‑specific)
Ontario's Development Code uses named, city‑specific district labels rather than generic "R‑1/R‑2" alone. The base district families and representative districts are:
Residential districts: AR‑2, RE‑2, RE‑4, LDR‑5, MDR‑11, MDR‑18, MDR‑25, HDR‑45 (density ranges and project standards are in the residential tables in Division 6.01). § 6.01.010
Mixed‑use districts: a family of MU districts (e.g., MU‑1 (Downtown Mixed Use), MU‑3 (East Guasti), MU‑6 (East Holt), MU‑8B / MU‑8C / MU‑8D / MU‑8E), each with specific density/FAR caps and, in places, a Planned Unit Development requirement; the MU districts are defined in § 6.01.020 and described in the MU sub‑sections. § 6.01.020
Commercial districts: multiple commercial designations and specialized commercial types are handled via Table 5.02‑1 and the commercial district development standards in Division 6.01 (see Table 6.01‑8 for commercial standards). § 5.02.010 § 6.01.015
Industrial / Business Park: BP (Business Park), IP (Industrial Park), IL (Light Industrial), IG (General Industrial) — each has an allowable FAR/intensity and use limitations to buffer residential uses. § 5.01.005
Open Space / Special: OS‑R (Open Space‑Recreation), OS‑C (Open Space‑Cemetery), UC (Utility Corridor), RC (Rail Corridor), PUD (Planned Unit Development) and SP (Specific Plan) districts (SP and PUD often supersede base‑zoning rules for sites covered by a specific plan or master plan). § 5.01.005 § 4.01.035
How uses are controlled: the Land Use Matrix (Table 5.02‑1) sets whether a use is permitted, conditionally permitted, or prohibited; anything not listed is treated as prohibited unless the Zoning Administrator makes a land use determination per § 5.02.010.C. § 5.02.010
Citywide development standards (high‑level practical orientation)
Where to look: the numeric and dimensional rules are concentrated in Chapter 6.0 (District Standards and Guidelines and the tables in Division 6.01), with cross‑references to parking in Division 6.03, fences in 6.02, and landscaping in 6.05. § 6.01.010 § 6.03
Setbacks and separations: minimum setbacks from public streets vary by street class (example minimums in the code: Freeways – 20 ft, Arterials – 30 ft, Collectors/Local – 20 ft (front), Street sides – 10 ft, Street rear – 15 ft), and interior side/rear minimums for many residential districts are 4 ft (and special buildable area rules exist for small‑lot projects). See the building development standards and district tables in § 6.01.010 and related district tables. § 6.01.010
Heights and FAR: district tables show maximum heights (many residential zones reference 35 ft as a common cap for low‑rise areas, subject to airport ALUCP limits) and FAR limits for mixed‑use and industrial districts (e.g., BP/IP typical max 0.6 FAR, IL/IG ~0.55 FAR — see the industrial district descriptions). ALUCP (airport) restrictions may further limit height and FAR. § 6.01.010 § 5.01.005
Lot coverage & open space: the Development Code publishes tables with maximum lot/project coverage and minimum private/common open‑space requirements by residential zone and project type (single‑family, small‑lot, multiple‑family). See the tables in Division 6.01 and the ADU tables that reference lot coverage limits. § 6.01.010
Parking (how many spaces and exceptions): parking requirements are in Division 6.03 and Table 6.03‑1; typical residential rates are bedroom‑based, garages are dimensioned, and ADUs have tailored parking rules (one space per ADU or bedroom, with multiple state‑law exceptions). § 6.03 § 5.03.010.F.6
Walls, fences and obstructions: dimension and location rules are in § 6.02.020 (e.g., front setback walls in commercial/mixed‑use limited to 3 ft; certain industrial fences allowed taller). § 6.02.020
Design and architectural controls: many districts (especially the MUs and the Downtown MU‑1) require conformance with the Downtown Ontario Design Guidelines and district‑specific guidelines; Certificates of Appropriateness and design review (historic areas / Euclid Avenue) use the development‑plan and historic preservation procedures. See § 6.01.020 (MU districts) and the Downtown design guidance cross‑references. § 6.01.020 § 6.01.035 (EA Overlay)
Practical note: specific numeric limits (setbacks, height, coverage) are table‑driven and district‑specific — always check the district table for the parcel and any Specific Plan or Overlay that applies to the site. § 6.01.010
Specific plans & overlays (how they alter the rules)
Specific Plans and PUDs: properties inside a Specific Plan (SP) or a Planned Unit Development (PUD) are regulated primarily by the adopted specific plan or PUD document; where a Specific Plan conflicts with the Development Code its standards govern; where a Specific Plan is silent, the Code applies. See § 1.01.035 and § 4.01.035 for the rule of precedence and PUD adoption. § 1.01.035 § 4.01.035
Overlay districts: Ontario uses overlays to layer additional rules and permissions on top of base zones. Key overlays include AG (Agriculture Overlay), EA (Euclid Avenue Overlay), ES (Emergency Shelter Overlay), MTC (Multimodal Transit Center Overlay), ICC (Interim Community Commercial), AH (Affordable Housing Overlay), and airport overlays (Chino/ONT). Overlay rules and applicability are described in the overlay section and § 6.01.035 (Overlay Zoning Districts). For example, the EA (Euclid Avenue) Overlay protects historic Euclid Avenue and may require a Certificate of Appropriateness for projects requiring Development Plan approval. § 6.01.035 § 6.01.035 (EA)
How overlays operate: overlays either add required findings/standards, allow interim uses (e.g., MTC allowing limited industrial uses in existing buildings while a multimodal center is planned), or mandate additional design controls. See the MTC and ES overlay descriptions in Division 5.01 and overlay standards in § 6.01.035. § 5.01.005.F
Building permits & review — the typical permit path
Ministerial vs discretionary pathways: Many routine permits are ministerial (no public hearing) under Division 4.03, but larger or potentially impactful projects require discretionary review under Division 4.02 (Development Plans, Conditional Use Permits, Variances). See the Review Matrix in Division 2.02 to know which path applies to your project. § 4.03.000 § 4.02
Development Plan triggers: Development Plan approval is required for projects of a certain size or type (examples: 3+ units on a single lot, conversions, significant nonresidential additions, or projects indicated in Table 2.02‑1); see the Development Plan applicability list in § 4.02.025. § 4.02.025
Historic and design review: projects in identified historic districts or the EA Overlay must follow historic preservation procedures (Certificates of Appropriateness) and the Downtown Design Guidelines; adaptive reuse has its own ministerial pathway in § 4.03.010. § 4.02.050 § 4.03.010
Building permits and code compliance: a complete building‑permit application is processed under the Development Code standards in effect on the application date, and building permit issuance is coordinated with Planning review and other city departments — the Development Code notes that applicants may still need other municipal permits and that building standards (Title 24 / the California Building Standards Code) apply. § 1.01.015
Ministerial ADU permits: Accessory Dwelling Units and Junior ADUs that meet the objective standards in § 5.03.010 are ministerial; Ontario must determine completeness within the state‑law timeframes and cannot subject compliant ADUs to discretionary review. ADU ministerial timing, size limits, setbacks and parking exceptions are spelled out in § 5.03.010.D–F. § 5.03.010.D § 5.03.010.F
State housing law in Ontario — how California rules are folded into the local code
Ontario implements California housing statutes within its Development Code; the local provisions explicitly reference state law and set local objective standards consistent with state mandates.
ADUs and JADUs: Section 5.03.010 implements ADU/JADU law (citing Government Code Chapter 13 of Title 7) and sets ministerial processing rules, size and setback caps, parking exceptions, sprinkler and occupancy rules, and legalization of pre‑2020 unpermitted ADUs consistent with state law. For ministerial ADUs, Ontario will make completeness determinations and process permits within the statutorily prescribed timing. § 5.03.010.A–D § 5.03.010.F
Two‑Unit Projects (SB 9 / GC 65852.21‑style rules): The city adopted a local implementation that allows ministerial Single‑Family Two‑Unit Projects under § 5.03.403 (implemented consistent with GC § 65852.21) and a separate Urban Lot Split process in Division 6.08 for ministerial parcel splits consistent with state law (unit counts, minimum lot sizes, height limits, utility/septic rules, and specific deed‑restriction and owner‑occupancy requirements are spelled out). See § 5.03.403 and the Urban Lot Split rules in § 6.08. § 5.03.403 § 6.08
Density bonus and other statewide incentives: Ontario’s Development Code includes the procedural and interpretation provisions to apply state density bonus and related incentives where applicable; consult the Land Use Matrix and the implementing sections when seeking density bonus concessions (see Division 5.02 and cross‑references in Division 4.02). § 5.02.010
Rent control and protected housing: Ontario’s code expressly protects certain housing from being altered or demolished through Urban Lot Split and Two‑Unit Project rules (no displacement of income‑restricted units or units under public rent controls). See the Urban Lot Split and Two‑Unit Project limitations in § 6.08 and § 5.03.403. § 6.08 § 5.03.403.E
Practical summary: the city’s ADU and Two‑Unit Project provisions are explicitly written to comply with state law while adding objective local standards (sizing, setbacks, parking exceptions, owner‑occupancy/deed restrictions for splits) and ministerial timelines. § 5.03.010 § 5.03.403
Source References
- Ontario Development Code — Table of contents and Division/Section listings (shows Chapters 1–6 and key sections) § 1.01.000, § 2.02.015, § 5.01.005
- Consistency with The Ontario Plan (General Plan) and ALUCP: § 1.01.025, § 1.01.020
- Planned Unit Development and Specific Plan rules: § 4.01.035
- Discretionary and ministerial permit divisions; Development Plan triggers: § 4.02 and § 4.02.025
- Ministerial/Administrative permits and adaptive reuse: § 4.03.000–4.03.010
- Base zoning district establishment and district descriptions (MU, industrial, PUD, SP, OS, UC): § 5.01.005 and related sub‑sections (MU descriptions)
- Land Use Matrix (Table 5.02‑1) and general land‑use provisions: § 5.02.010
- ADU / JADU rules and ministerial processing: § 5.03.010 (D–F)
- Single‑Family Two‑Unit Projects and ministerial approval: § 5.03.403
- Urban Lot Split (ministerial parcel split) and related limits: Division 6.08 (Urban Lot Split rules) § 6.08
- District development standards, setbacks, heights, lot coverage, and small‑lot rules: Division 6.01 and Tables (e.g., Table 6.01‑2, 6.01‑3) § 6.01.010
- Parking tables and standards: Division 6.03 and Table 6.03‑1 § 6.03
- Overlay district rules (EA, MTC, ES, AG, AH, ICC): § 6.01.035 and overlay descriptions in Division 5.01
Where to read the Ontario code
The Ontario municipal and zoning code is published on American Legal Publishing — view the official Ontario code library. That lets you read the ordinance section by section.
GoCodebook goes beyond browsing American Legal Publishing (see how they compare): it reads the Ontario ordinance together with the California Building Standards Code and answers your question — zoning, setbacks, FAR, height, ADUs, permits — with the controlling citation for your parcel.
Who this affects
Frequently asked questions
What zoning districts does Ontario use for residential land?
Ontario uses city‑specific residential zone labels such as AR‑2, RE‑2, RE‑4, LDR‑5, MDR‑11, MDR‑18, MDR‑25, and HDR‑45; the district tables with densities, setbacks and coverage are in the residential tables of Division 6.01. § 6.01.010
Where do I look to see whether a specific use is allowed on my property?
Start with the Zoning Map (adopted under § 5.01.015), then check the Land Use Matrix (Table 5.02‑1) which shows permitted, conditionally permitted, and prohibited uses; if a use is not listed, the Zoning Administrator can make a land‑use determination per the code. § 5.01.015 § 5.02.010
Do I need a Development Plan or discretionary review for my project?
Many projects are ministerial, but projects meeting the Development Plan triggers (for example, development of 3 or more dwelling units on a single lot, certain commercial additions, or conversions listed in the Review Matrix) require a Development Plan under Division 4.02 and Table 2.02‑1. Check § 4.02.025 and the Review Matrix to confirm. § 4.02.025
How does Ontario implement ADU rules and do ADUs require discretionary review?
Accessory Dwelling Units and Junior ADUs are governed by § 5.03.010; compliant ADUs that meet the objective standards are approved ministerially (building permit only), with required timeframes for completeness determinations and ministerial processing described in that section. § 5.03.010.D
Can I split my lot under SB 9 / Two‑Unit Project rules or the Urban Lot Split?
Ontario provides two tracks: a ministerial Two‑Unit Project implementation under § 5.03.403 (consistent with GC § 65852.21) and a ministerial Urban Lot Split process in Division 6.08 for parcel splits; both carry objective limits on lot size, unit size, parking, owner‑occupancy/deed restrictions and exclusions for certain protected sites. § 5.03.403 § 6.08
What are the city's parking rules for ADUs and when are parking spaces waived?
ADU parking is addressed in § 5.03.010.F.6: generally one off‑street parking space per ADU or per bedroom is required, but the code lists specific exceptions (e.g., within one‑half mile of transit, in historic districts, when attached to the main residence, or when car‑share is within one block). § 5.03.010.F.6
Does Ontario have special rules for Euclid Avenue or historic areas?
Yes — the EA (Euclid Avenue) Overlay applies design protections and can require a Certificate of Appropriateness for projects requiring Development Plan approval; adaptive‑reuse and downtown design rules are referenced in the overlay text. See § 6.01.035 (EA Overlay) and the Downtown Design Guidelines references. § 6.01.035
If my parcel is in a Specific Plan, which rules control?
An adopted Specific Plan supersedes the Development Code where there is a conflict; where the Specific Plan is silent the Development Code applies. The relationship and precedence are described in § 1.01.035 and the PUD/Specific Plan rules. § 1.01.035
Where are setbacks, height limits and lot coverage published?
Numerical setbacks, building separations, maximum heights and lot/project coverage are published in the district standards and development tables in Chapter 6.0 (Division 6.01) and cross‑referenced through each zoning district’s table. See § 6.01.010 and related tables (Table 6.01‑2, Table 6.01‑3, etc.). § 6.01.010
Does Ontario have local rent control that affects Two‑Unit Projects or Urban Lot Splits?
The Development Code expressly prevents Urban Lot Splits and Two‑Unit Project approvals from targeting or demolishing income‑restricted housing or housing subject to public rent regulations; see the prohibitions and requirements in the Two‑Unit Project and Urban Lot Split sections. § 5.03.403.E § 6.08
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