ADU Pass
Brown County
ADU Pass helps homeowners in Brown County, Ohio navigate the permit paperwork for building an accessory dwelling unit. We cover 11 cities and 12 ZIP codes in this county.
Map
County ADU details
County ADU ordinance
Brown County, Ohio (rural southwest-Ohio county on the Ohio River; ~43,500 residents; county seat Georgetown — boyhood home of Ulysses S. Grant; 16 townships including Byrd, Clark, Eagle, Franklin, Green, Huntington, Jackson, Jefferson, Lewis, Perry, Pike, Pleasant, Scott, Sterling, Union, and Washington; incorporated villages Aberdeen, Fayetteville, Georgetown, Hamersville, Higginsport, Mount Orab, Ripley, Russellville, and Sardinia) 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 Brown County has not. Townships in Brown County may adopt township-tier zoning under O.R.C. Chapter 519, and a minority have done so — Pike Township (containing fast-growing Mount Orab on the U.S. 32 'Appalachian Highway' corridor) has the most-developed township zoning resolution, and several townships closer to the Cincinnati commute shed (Jackson, Pleasant) have partial zoning. The rest of Brown County's townships have NO township zoning resolution in force. Where neither county nor township zoning exists, a parcel in unincorporated Brown 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 Brown County General Health District still governs septic permits, but there is no local zoning prohibition on a second dwelling on a parcel. ADU permissibility in unincorporated Brown County therefore turns on (1) whether the parcel is in a township with adopted zoning (a minority but a growing one along U.S. 32), (2) whether the parcel is inside village limits (in which case the village's zoning applies — Mount Orab and Georgetown have the most active village zoning), and (3) whether the parcel can support a second septic field under OAC 3701-29 capacity rules.
County assessor
Assessment policy: The Brown County Auditor (Torrey Sheets, 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 update or 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. Brown County also administers Current Agricultural Use Valuation (CAUV) under O.R.C. § 5713.30 - § 5713.38 — a significant program here because most of the county outside the U.S. 32 corridor 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; the Auditor's CAUV reviewers 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. Brown County's last sexennial reappraisal was in 2023 with a 2026 triennial update scheduled.
County overlays (4)
Known county issues (6)
- 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 Pike Township (Mount Orab area) and inside Mount Orab or Georgetown village limits require township- or village-specific review and likely face stricter accessory-dwelling provisions.
- other — ADU applicants must coordinate across four or five separate state and county agencies rather than a single one-stop county counter. Lead times are correspondingly longer; DIC inspector trip routing from the regional office adds friction relative to counties with their own staff. Cellular and broadband coverage gaps in the eastern and southern townships complicate online portal use.
- other — Researchers should not aggregate ADU policy or cost data across the whole county without splitting on the U.S. 32 corridor versus the rural balance. A median ADU cost or permit-duration figure for the county as a whole will mislead consumers about both environments.
- other — ADU economics in rural Brown County are typically dominated by septic and site-prep costs, not by permit fees or zoning. Researchers projecting ADU build cost in unincorporated rural Brown County should use a septic-cost band of $12,000-$30,000 (advanced system probable in eastern/southeastern townships) rather than the $5,000-$10,000 conventional band typical for flatter Ohio counties. Inside Mount Orab and the sewer-served portions of Georgetown the cost picture is closer to a typical Ohio suburban village.
- historic-restriction — ADU projects in Ripley's historic-district footprint face design-review obligations that other Brown County villages do not impose. Researchers should not extrapolate Ripley's ADU permit timeline or cost to other Brown County villages.
- policy-review — Researchers should monitor the Ohio General Assembly for any future ADU preemption proposal; until one passes, Brown 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.