ADU Pass
Ontario
ADU Pass helps homeowners in Ontario, San Bernardino County, California navigate the permit paperwork for building an accessory dwelling unit. This area covers 3 ZIP codes.
Map
ADU details
ADU legality: allowed
California state law preempts most local restrictions. Ontario applies the statewide ministerial framework via Development Code §5.03.010 and processes applications through the Citizen Portal. AICUZ noise overlay (LDN 60-65) adds sound-attenuation requirements and a city-council hearing for some new dwellings; LDN 65 prohibits new residential.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 150 | $1,850 | $64,500 | $66,350 |
| 600 | 600 | $2,900 | $258,000 | $260,900 |
| midpoint | 675 | $3,100 | $290,250 | $293,350 |
| 1000 | 1,000 | $9,300 | $430,000 | $439,300 |
| maximum | 1,200 | $10,800 | $516,000 | $526,800 |
Fee breakdown (as of 2026-04)
Permitting process
Viability (permitted uses)
- Long-term rental: yes Long-term ADU rental permitted; AB 976 (effective 2024-01-01) bars Ontario from imposing owner-occupancy as a permit condition.
- Short-term rental: with-restrictions Ontario regulates STRs separately from ADU permitting; check current STR ordinance and any HOA covenants on the parcel.
- Office rental: with-restrictions Renting an ADU as outside-tenant office space requires a use change beyond residential; consult Planning Counter.
- Home office: yes Owner home-office use within an ADU permitted as accessory residential use; standard home-occupation limits on signage and customer traffic apply.
- Studio / workshop: yes Owner artist studio / workshop use within an ADU permitted as accessory residential use.
- Agriculture: with-restrictions Limited urban agriculture allowed in residential zones per Development Code; livestock varies by district. ADU itself cannot be the agricultural structure.
- Relative support: yes Family / multigenerational use of ADU explicitly permitted. JADU (under 500 sqft) attached to a single-family home is well-suited to relative-support use.
Incentives
Pre-approved plans Pre-approved plans
Contacts
Utilities
- Water: Ontario Municipal Utilities Company (OMUC) · 21d connect · $4,500
OMUC manages 630+ miles of potable water lines and 45,000+ service connections. New rates effective 2025-11-01. Meter required only when applicant requests separate billing or for ADUs over 750 sqft per OMUC discretion. - Sewer: Ontario Municipal Utilities Company (OMUC) · 21d connect · $6,955
Sewer assessment is $6,955 per dwelling unit (or fixture-unit basis for commercial) per Ontario Building Department fee schedule. 450+ miles of gravity sewer. Waived for ADUs under 750 sqft per SB 13. - Electric: Southern California Edison (SCE) · 30d connect · $1,800
SCE serves all of Ontario. Standard residential service drop; separate meter optional. Title 24 2025 solar mandate applies to new detached ADUs. - Gas: Southern California Gas Company (SoCalGas) · 21d connect · $1,500
SoCalGas serves Ontario. All-electric ADUs may skip the gas connection; no Ontario gas-ban ordinance is in effect.
Property values & taxes
Construction timeline
Realistic total: best 7mo · typical 11mo · worst 17mo
Modular pathway inspectors are experienced with modular
Financing
Insurance impact
Inland Empire premium is moderate vs coastal CA: lower wildfire-zone exposure than foothill Rancho Cucamonga, but airport noise / flight-path liability and Cucamonga Creek SFHA flood-insurance exposure on some parcels.
HOA prevalence & preemption
California's AB 670 (2019) + AB 3182 (2020) preempt HOA ADU bans in single-family CIDs (Civil Code §§ 4740/4741). Ontario's planned communities (e.g. New Model Colony / Ontario Ranch) carry significant HOA coverage but the state preemption applies. HOAs may still impose reasonable design standards (Carlsbad-pattern delays).
Regulatory overlays (3)
- airport-noise-zone
Ontario International Airport ALUCP / AICUZ overlay: LDN 65 contour prohibits new residential; LDN 60-65 'special noise impact district' permits residential only after city-council hearing and requires 45 CNEL interior sound attenuation. Affects parcels south/west of ONT runways. - flood-zone
Cucamonga Creek and Chino Creek SFHA reaches cross northern and southwestern Ontario; FEMA Zone A / AE applies on those parcels and triggers floodplain elevation + insurance requirements. - seismic-retrofit-zone
Ontario lies within the broader Cucamonga / San Jacinto fault region (SDC D); ASCE 7-22 seismic detailing required, but no city-specific soft-story or URM retrofit overlay.
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
- Amendment
Contractor market (aggregate)
Legal history (timeline)
Current ordinance: Ontario Development Code §5.03.010 — Accessory Dwelling Units and Junior Accessory Dwelling Units, adopted 2017-01-01, last amended 2024-12-11
- 2011-04-19 — Ontario adopts ONT International Airport Land Use Compatibility Plan (ALUCP) (city-ordinance)
Ontario City Council adopted the ONT ALUCP, codifying the AICUZ noise contours and compatibility districts that constrain residential construction near the airport.
Effect: Created the AICUZ overlay that bars new residential in LDN 65 contour and requires sound-attenuation (interior 45 CNEL max) plus city-council approval for residential in the LDN 60-65 special-noise district. Affects ADU eligibility on parcels within the contours. - 2017-01-01 — Ontario Development Code §5.03.010 — initial ADU/JADU compliance update (city-ordinance)
Ontario amended Development Code Chapter 5 to align with then-new SB 1069 / AB 2299 ADU statutes, adopting ministerial review and statutory size envelopes.
Effect: Created the §5.03.010 framework Ontario still uses. Replaced the prior 'second-unit' permitting regime with the statewide ministerial process. - 2020-01-01 — Ontario §5.03.010 conformance update for AB 68 / SB 13 / AB 670 cycle (city-ordinance)
Ontario updated the local ADU ordinance to incorporate the 2020 statewide preemption package: 60-day clock, fee caps under 750 sqft, parking exemptions near transit, void HOA covenants.
Effect: Removed the few remaining discretionary review hooks; aligned Ontario with the 60-day deemed-approval rule and the under-750-sqft fee waiver. - 2024-12-11 — Ontario Building Permit Application form revision (Rev. 12-11-2024) (city-ordinance)
Ontario published a refreshed Building Permit Application referenced from the ADU Permit Process page (Rev. 12-11-2024); ADU Plan Submittal Requirements last refreshed 2024-10-04.
Effect: Current intake forms applicants must use; previous form revisions are rejected at the Citizen Portal. - 2025-08-04 — Ontario partners with Symbium for Real Time Permitting (residential solar / energy storage) (city-policy)
Effective 2025-08-04, contractors and homeowners can pull permits for residential solar and energy storage systems via the Symbium real-time permitting portal.
Effect: Faster solar/ESS-only permits (relevant to Title 24 solar mandate on new ADUs); ADU shell permits still flow through the Citizen Portal multi-department plan check. - 2025-11-01 — Ontario Municipal Utilities Company new water/sewer rates effective (city-policy)
OMUC implemented new water, sewer, and integrated-waste rates on 2025-11-01; affects ADU connection charges and ongoing utility cost estimates.
Effect: Connection-fee schedule and monthly rates updated; pre-Nov-2025 cost estimates for OMUC service are stale.
Known issues (2)
- other — Ontario International Airport AICUZ overlay (LDN 60-65) blocks or materially constrains ADU permitting on parcels under the noise contour, particularly in older neighborhoods south and west of the airport. LDN 65 is an outright residential prohibition; LDN 60-65 requires a city-council hearing and 45 CNEL interior attenuation.
- other — OMUC sewer assessment of $6,955 per dwelling unit is a meaningful sticker shock for ADUs over 750 sqft (under-750-sqft ADUs are SB-13 exempt). Plan accordingly when sizing the unit.
San Bernardino County — county ADU rules and overlays
County ADU ordinance
California state — ADU law and programs
State ADU law
California has the most aggressive statewide ADU preemption regime in the US, built from ~15 bills passed 2019-2025 and enforced by the Department of Housing and Community Development (HCD). The 2026 HCD ADU Handbook addendum (in effect with the 2025 Title 24 code cycle) is the operative state-level reference. The regime does four things at once: (1) preempts local zoning that would ban or unreasonably restrict ADUs; (2) imposes by-right ministerial approval with short statutory deadlines; (3) caps fees and utility-connection charges; and (4) empowers HCD to void non-compliant local ordinances.
State HOA preemption
California has the strongest statewide HOA-preemption regime in the US for accessory dwelling units, built from two bills: AB 670 (2019) voided ADU-prohibiting covenants on single-family residential lots, and AB 3182 (2020) extended and codified the preemption into the Davis-Stirling Common Interest Development Act (Civil Code §§ 4740 / 4741). The combination prohibits common-interest communities from banning ADUs, restricting rentals below 25% of separate interests, or treating ADUs as separate HOA interests. Limits remain: HOAs retain authority over reasonable design standards and statutory height limits, and the 2026 Carlsbad case (CalMatters coverage) established that an HOA's documented design-standards regime can effectively delay or constrain ADU approval short of outright prohibition.
State financing programs
California's flagship state-level ADU financing program — the CalHFA ADU Grant Program — is paused and has not been refunded since the original $100 million allocation was fully deployed 2023-12-28. The program provided up to $40,000 per qualifying homeowner for pre-construction and non-recurring closing costs and financed approximately 2,500 ADUs in two rounds. As of 2026-04, no new funding round has been announced in the state budget. CalHFA continues to publish anti-scam warnings because bad actors actively solicit homeowners claiming access to grant funds that no longer exist. State-level financing activity has shifted to local pilot programs (San Francisco, San Jose, Los Angeles, San Diego) and private financing products (Fannie Mae ADU mortgage, HELOC, construction-to-permanent).
State housing programs
California's state-level ADU programs are concentrated at HCD (technical guidance, ordinance review, enforcement) and the paused CalHFA grant pipeline (covered under stateFinancing). The state does not operate a central pre-approved ADU plan library — instead, AB 1332 (2024) created a preemption framework for local pre-approved plans with a 30-day ministerial-approval deadline, and major cities (Los Angeles, San Diego, San Jose, Sacramento, Berkeley) have rolled out their own plan catalogs. The California YIMBY coalition and other housing-policy organizations play an influential role in bill drafting; they are not state agencies but effectively drive much of the ADU legislative agenda. The Title 24 code cycle (now 2025, in effect for 2026 permits) is the authoritative building-code baseline.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.
ZIP Codes
- 91761
- 91762
- 91764
Post Office
- 1126 N Mountain Ave, 91762
- 123 W Holt Blvd, 91762
- 1555 E Holt Blvd, 91761