ADU Pass
Fairfield County
ADU Pass helps homeowners in Fairfield County, Ohio navigate the permit paperwork for building an accessory dwelling unit. We cover 14 cities and 19 ZIP codes in this county.
Map
County ADU details
County ADU ordinance
Fairfield County (county seat Lancaster; ~162,000 residents in central Ohio, in the Hocking Hills foothills southeast of Columbus) regulates land use in unincorporated areas primarily through township-tier zoning under Ohio Revised Code Chapter 519, with the Fairfield County Regional Planning Commission (FCRPC, codified locally under Resolution of the Board of County Commissioners and ORC § 713.21 et seq.) providing professional planning, subdivision review, and contract-zoning administration for thirteen townships that have adopted FCRPC services. Ohio is a Dillon's Rule state with home-rule for charter municipalities under Ohio Const. Art. XVIII; counties in Ohio may not directly zone unincorporated territory (with the narrow Lake County and Summit County exceptions under ORC Chapter 303), so Fairfield County's role is advisory + administrative rather than a county-tier zoning code. The Fairfield County Regional Planning Commission acts as zoning inspector under contract for Berne, Bloom, Greenfield, Hocking, Liberty, Madison, Pleasant, Richland, Rush Creek, Violet, Walnut, and certain other townships; each township's zoning resolution remains the operative ADU instrument. ADU permissibility, owner-occupancy, parking, and size limits are set in the individual township zoning resolution, not in any county-wide ordinance. The FCRPC publishes a model zoning resolution and assists townships with text amendments; recent (2023-2025) FCRPC commentary has flagged ADU/in-law-suite as an emerging issue but no model ADU text has been adopted county-wide.
State-floor overlay: No Ohio statewide ADU preemption is in force as of 2026-05-20 (see ohio.json stateAduLaw). Authority over ADU permissibility rests with each township and incorporated municipality.
Adopting body: Fairfield County Board of Commissioners (FCRPC oversight and budget); individual township trustees adopt the operative zoning resolutions
County assessor
Assessment policy: The Fairfield County Auditor (Ohio uses elected County Auditors as the property-assessment authority under ORC § 5713.01) assesses real and personal property. Ohio assesses real property at 35% of true value (ORC § 5713.03). Fairfield County's sexennial reappraisal cycle (Ohio mandatory schedule under ORC § 5715.16) last completed in 2022; triennial update due 2025. New ADU construction is reassessed at true value as of January 1 following completion; the appraiser visits or uses building-permit notification. Ohio's Owner Occupancy Credit (ORC § 323.151 et seq.) gives a 2.5% reduction on the owner-occupied homestead tax bill; the Homestead Exemption (ORC § 323.151) shields $25,000 of taxable value for owners 65+ or permanently disabled (income-qualified at ~$38,600 OAGI as of 2025). An ADU rented to a non-family tenant typically carves a non-homestead share of valuation off the homestead credit base.
County overlays (4)
Known county issues (4)
- other — Per-township variation is the norm. Violet and Bloom (the rapidly suburbanizing northern townships adjacent to Pickerington) tend to have the most modern zoning text; Berne, Rush Creek, and Hocking (southern, rural) have older resolutions that are typically silent on ADUs and read as prohibitions by default.
- other — Researchers must consult the Pickerington and Canal Winchester city ADU rules irrespective of which county a particular parcel sits in. County-tier research applies only to the FCRPC unincorporated-territory rule and the county auditor.
- other — ADU research for parcels in the Buckeye Lake region of Fairfield (Walnut Township, near Millersport) must cross-reference the Buckeye Lake Region Water and Sewer District (BLRWSD) capacity rules in addition to Walnut Township zoning.
- other — Lancaster city-tier research must address the historic-district overlay; the county role in those parcels is limited to the auditor record.
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.