ADU Pass
Adams County
ADU Pass helps homeowners in Adams County, Ohio navigate the permit paperwork for building an accessory dwelling unit. We cover 10 cities and 11 ZIP codes in this county.
Map
County ADU details
County ADU ordinance
Adams County, Ohio (rural Appalachian county on the Ohio River; ~27,500 residents; county seat West Union; 15 townships including Bratton, Brush Creek, Franklin, Green, Jefferson, Liberty, Manchester, Meigs, Monroe, Oliver, Scott, Sprigg, Tiffin, Wayne, and Winchester; incorporated places West Union (village), Manchester (village), Peebles (village), Seaman (village), and Winchester (village)) does NOT operate a countywide zoning ordinance and has not adopted county-tier zoning under O.R.C. Chapter 303. Ohio is a home-rule state under Article XVIII of the Ohio Constitution; counties may adopt county zoning under O.R.C. Chapter 303 but most do not (Lake County is the canonical Ohio county that does), and Adams County has not. Townships in Adams County may adopt township-tier zoning under O.R.C. Chapter 519, but as of 2026-05 most Adams County townships have NO township zoning resolution in force. Where neither county nor township zoning exists, a parcel in unincorporated Adams County is effectively unzoned for land-use purposes; the Ohio Residential Code (OAC 4101:8) still governs construction standards for any dwelling, including an ADU, and the Adams County Health Department still governs septic permits, but there is no local zoning prohibition on a second dwelling on a parcel. ADU permissibility in unincorporated Adams County therefore turns on (1) whether the parcel is in a township with zoning (a minority), (2) whether the parcel is inside village limits (in which case the village's zoning applies), and (3) whether the parcel can support a second septic field under OAC 3701-29 capacity rules.
County assessor
Assessment policy: The Adams County Auditor (David Gifford, 2026) is the elected property-assessment authority under O.R.C. § 5713.01. Ohio assesses real property at 35% of true value (O.R.C. § 5713.03). New ADU construction is added to the parcel record on the next regular revaluation cycle and reassessed at true value as of January 1 following completion. The Ohio Owner Occupancy Credit (O.R.C. § 323.151 et seq.) provides a 2.5% reduction in tax on owner-occupied homestead; the Homestead Exemption (O.R.C. § 323.152) reduces taxable value by $25,000 for owners 65+ or totally and permanently disabled, subject to income tests. Adams County also administers Current Agricultural Use Valuation (CAUV) under O.R.C. § 5713.30 - § 5713.38 — a significant program here because much of the county is enrolled CAUV farmland. An ADU built on a CAUV parcel may trigger a partial recoupment (rollback) if the dwelling reduces the parcel's qualifying agricultural acreage below the CAUV threshold; CAUV reviewers in Adams County examine ADU additions case-by-case. Under O.R.C. § 5713.17, the owner must notify the Auditor of any construction or improvement valued over $2,000.
County overlays (4)
Known county issues (5)
- other — Researchers should verify the township for any specific parcel before assuming ADU prohibition or permission. Parcels in unzoned townships have unusually permissive ADU conditions for Ohio, constrained mainly by septic capacity and floodplain. Parcels in the few zoned townships and inside village limits require township- or village-specific review.
- other — ADU applicants must coordinate across three or four separate state and county agencies rather than a single one-stop county counter. Lead times are correspondingly longer; DIC inspector trip routing from Reynoldsburg or a regional office adds friction relative to counties with their own staff. Cellular and broadband coverage gaps complicate online portal use.
- other — Enumeration of Adams County cities here includes 'portsmouth' for fidelity to the city-highlights tree, but consumers should not attribute Portsmouth's ~18,252 residents to Adams County. Adams County's actual incorporated places are West Union (village, county seat), Manchester (village), Peebles (village), Seaman (village), and Winchester (village); plus several unincorporated communities (Bentonville, Blue Creek, Cherry Fork, Stout, and others).
- other — ADU economics in Adams County are typically dominated by septic and site-prep costs, not by permit fees or zoning. Researchers projecting ADU build cost in unincorporated Adams County should use a septic-cost band of $12,000-$35,000 (advanced system probable) rather than the $5,000-$10,000 conventional band typical for flatter Ohio counties.
- policy-review — Researchers should monitor the Ohio General Assembly for any future ADU preemption proposal; until one passes, Adams County remains in the rare position where unincorporated unzoned-township parcels are de facto permissive without any state preemption being needed.
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.