ADU Pass
Fullerton
Orange County portion
Also in: No County
ADU Pass helps homeowners in Fullerton, Orange County, California navigate the permit paperwork for building an accessory dwelling unit. This area covers 4 ZIP codes.
Map
ADU details
ADU legality: allowed
Fullerton ADU framework conforms to California state preemption (FMC § 15.17.100, codified through Ordinance 3313 in 2022). 160 ADUs were permitted citywide in 2025 per Fullerton's Housing Element APR.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 150 | $1,700 | $71,250 | $72,950 |
| 600 | 600 | $1,700 | $285,000 | $286,700 |
| midpoint | 675 | $1,700 | $320,625 | $322,325 |
| maximum | 1,200 | $1,700 | $570,000 | $571,700 |
Fee breakdown (as of 2026-04)
Permitting process
Viability (permitted uses)
- Long-term rental: yes Long-term rental of detached and attached ADUs is explicitly permitted. California's owner-occupancy preemption applies to ADUs (but not JADUs).
- Short-term rental: with-restrictions Fullerton regulates short-term rentals separately from ADU permitting; verify the city's STR ordinance and HOA covenants before listing on Airbnb/VRBO. Some single-family zones restrict STR use.
- Office rental: with-restrictions Renting an ADU as office space to outside tenants requires a home occupation permit or zoning change; Fullerton residential zones do not permit outright commercial use.
- Home office: yes Owner home-office use is permitted with limits on signage, customer traffic, and employees per FMC home occupation rules.
- Studio / workshop: yes Owner artist studio is a permitted accessory use in residential zones.
- Agriculture: with-restrictions Limited urban agriculture is permitted; livestock varies by district and is more restricted in R-1 zones.
- Relative support: yes Family-occupancy ADU and JADU pathways are explicitly permitted in single-family zones. JADU still requires owner-occupancy on the property.
Incentives
Contacts
Contractor directory (5)
Scope: city.
Utilities
- Water: City of Fullerton Water Utility (Public Works) · 21d connect · $4,500
- Sewer: City of Fullerton Sewer (Orange County Sanitation District for treatment) · 21d connect · $5,500
- Electric: Southern California Edison (SCE) · 14d connect · $1,800
- Gas: Southern California Gas Company (SoCalGas) · 21d connect · $1,500
Property values & taxes
Construction timeline
Realistic total: best 8mo · typical 12mo · worst 18mo
Modular pathway inspectors are occasional with modular
Financing
State ADU loans:
- CalHFA ADU Grant Program up to $40,000
- HCD ADU Funding index
Insurance impact
HOA prevalence & preemption
California has the strongest statewide HOA-preemption regime in the US for accessory dwelling units. AB 670 (2019) voided ADU-prohibiting covenants on single-family residential lots; AB 3182 (2020) extended the preemption into the Davis-Stirling Act (Civil Code §§ 4740 / 4741), prohibiting common-interest communities from banning ADUs, restricting rentals below 25% of separate interests, or treating ADUs as separate HOA interests. Fullerton's older Craftsman and Mid-Century Modern neighborhoods are mostly non-HOA; HOAs cluster in newer hillside subdivisions (e.g., Sunny Hills, parts of West Coyote Hills) and condominium developments.
Regulatory overlays (5)
- historic-district
Fullerton has 16 designated Historic Districts; 10 carry Residential Preservation Zone status. ADUs in those districts trigger Historic Preservation Commission review for compatibility with the citywide Design Guidelines (Ord. 2886, 1996). Notable districts include the SOHO / South of Harvard area near downtown. - wui-fire-zone
Per CalFire's 2025 LRA FHSZ map adopted by Fullerton in May 2025: 1,516 acres are now Very High FHSZ (a 28% increase over 2011), 419 acres High, and 426 acres Moderate. New zones concentrate in West and East Coyote Hills. Parcels in VHFHSZ trigger CBC Chapter 7A WUI ignition-resistant construction. - airport-noise-zone
Fullerton Municipal Airport (FUL) generates a noise contour over residential parcels northwest of the runway; affected ADUs may need sound-attenuation construction per FAR Part 150. - seismic-retrofit-zone
Seismic Design Category D2 per ASCE 7-22; the Whittier and Norwalk faults run nearby and the city sits on Quaternary alluvium with moderate liquefaction susceptibility. - flood-zone
Brea Canyon Wash (Coyote Creek tributary) crosses northern Fullerton; some parcels along Brea Creek lie in FEMA Zone AE.
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
Legal history (timeline)
Current ordinance: Fullerton Municipal Code § 15.17.100 — Accessory and Junior Accessory Dwelling Units, adopted 2017-01-01, last amended 2025-06-01
- 1996-03-05 — Ordinance 2886 — Fullerton Citywide Design Guidelines (Chapter 15.17 amendment) (city-ordinance)
Adopted citywide residential and commercial design guidelines as a Chapter 15.17 amendment.
Effect: Established the architectural-compatibility review framework that Fullerton later applied to ADU plans visible from public right-of-way per FMC § 15.17.100. - 2017-01-01 — Ordinance 3247 — initial Fullerton ADU code conforming to AB 2299 / SB 1069 (city-ordinance)
Adopted Fullerton's first dedicated ADU ordinance to conform with the 2017 California ADU statute updates.
Effect: Repealed legacy second-unit code; introduced ministerial review and removed discretionary findings for compliant ADUs. - 2018-01-01 — Ordinance 3267 — JADU integration and additional state-conformance amendments (city-ordinance)
Added Junior ADU pathway and aligned with the 2018 California ADU statute revisions.
Effect: Codified JADU as a distinct unit type capped at 500 sqft; preserved owner-occupancy on JADU lots. - 2020-04-07 — Ordinance 3280 — Fullerton ADU code aligned with AB 68/881/SB 13 (city-ordinance)
City Council approval (April 7, 2020) following Planning Commission recommendation Feb 19, 2020.
Effect: Removed owner-occupancy requirement for stand-alone ADUs; conformed setbacks, height, and ministerial review to the 2020 California framework. - 2022-01-01 — Ordinance 3313 — current FMC § 15.17.100 codification (city-ordinance)
Most recent Fullerton ADU ordinance codified at FMC § 15.17.100.
Effect: Confirms 1,200 sqft maximum ADU size, architectural compatibility for ADUs visible from public ROW, fire-sprinkler parity (sprinklers required only when also required for the primary dwelling), and explicit non-counting of ADUs against allowable density. - 2025-05-12 — Fullerton adopts updated CalFire Fire Hazard Severity Zone maps (city-ordinance)
City adopted CalFire's 2025 LRA FHSZ map update.
Effect: Very High FHSZ acreage in Fullerton increased 28% (1,186 → 1,516 acres), with new High and Moderate zones added in West and East Coyote Hills. ADUs in newly-mapped FHSZ parcels are subject to CBC Chapter 7A WUI ignition-resistant construction. - 2025-06-01 — Fullerton ADU impact-fee waiver expansion (city-ordinance)
Council amendment exempting ADUs under 750 sqft from impact fees (codifying SB 13 in local fee schedule).
Effect: Aligned Fullerton's local fee bundle with statewide fee preemption; reduced effective per-unit fee for sub-750-sqft conversions and JADUs. - 2025-09-16 — Council authorizes RRM Design Group pre-approved ADU plan contract (AB 1332 conformance) (city-ordinance)
Professional Services Agreement to develop a pre-approved ADU plan catalog conforming to AB 1332.
Effect: Pre-approved plan catalog under development as of late 2025; not yet available for permit submittal.
Known issues (3)
- fee-schedule-pending — Until the RRM-prepared catalog is published, all Fullerton ADUs require custom plans, which adds 4-8 weeks to the review cycle compared with neighboring Anaheim and Santa Ana that have pre-approved catalogs.
- policy-review — 1,516 acres of VHFHSZ as of 2025 (up 28%); ADUs in the newly-mapped VHFHSZ areas now require CBC Chapter 7A ignition-resistant exterior construction, which can add $15,000-$40,000 to a detached-ADU build.
- other — ADUs visible from public ROW in Fullerton's historic districts must conform to the 1996 Design Guidelines and pass HPC review, adding review time and constraining material/style options.
Orange 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
- 92831
- 92832
- 92833
- 92835
Post Office
- 1350 E Chapman Ave, 92834
- 1820 N Sunnycrest Dr, 92838
- 1920 W Commonwealth Ave, 92837