ADU Pass
Greene County
ADU Pass helps homeowners in Greene County, Ohio navigate the permit paperwork for building an accessory dwelling unit. We cover 11 cities and 19 ZIP codes in this county.
Map
County ADU details
County ADU ordinance
Greene County, Ohio (southwest Ohio immediately east of Dayton; ~169,000 residents as of the 2020 Census; county seat Xenia; established March 24, 1803 as one of Ohio's original counties; 12 townships - Bath, Beavercreek, Caesarscreek, Cedarville, Jefferson, Miami, New Jasper, Ross, Silvercreek, Spring Valley, Sugarcreek, Xenia; three cities (Beavercreek ~48,000, Fairborn ~33,452, Xenia ~25,976), the city of Bellbrook (~7,053), and five villages (Bowersville, Cedarville, Jamestown, Spring Valley, Yellow Springs)) is one of the minority of Ohio counties that DOES exercise county-tier zoning authority under O.R.C. Chapter 303. The Greene County Regional Planning and Coordinating Commission (GCRPCC) administers the Greene County Zoning Resolution for the seven townships that have adopted county zoning (rather than township-tier zoning under O.R.C. Chapter 519) - in practice most rural Greene County unincorporated territory falls under one of two regimes: county-tier zoning administered by GCRPCC for participating townships, or township-tier zoning for the larger townships (Beavercreek Township, Bath Township, and Sugarcreek Township each maintain township zoning resolutions and inspectors). Inside the three cities and four incorporated villages, municipal zoning controls; the county zoning resolution does not reach inside city or village corporate limits. The county also operates the Greene County Building Regulations Department, a certified building department under O.R.C. Chapter 3781 that enforces the Ohio Residential Code (OAC 4101:8) for one-, two-, and three-family dwellings across unincorporated Greene County and on a contract basis for several of the villages - this distinguishes Greene from most rural Ohio counties (where residential plan review falls to the Ohio Department of Commerce Division of Industrial Compliance). Greene County's adoption of both a county zoning resolution AND a certified county building department places it in a relatively small group of Ohio counties (with Cuyahoga, Hamilton, Franklin, Summit, Montgomery, and a few others) where land-use AND construction-code authority are both exercised at the county tier rather than deferred to state or township agencies. ADU permissibility on a given parcel in unincorporated Greene County therefore depends on (1) whether the parcel is in a township that has adopted county-tier zoning (GCRPCC administered) or township-tier zoning (Beavercreek / Bath / Sugarcreek), and (2) the specific zoning district classification. The Greene County Zoning Resolution does not list 'accessory dwelling unit' as a defined use; second dwellings on a single parcel typically require either a conditional use permit or a variance from the Greene County Board of Zoning Appeals (or the relevant township BZA where township zoning applies).
County assessor
Assessment policy: The Greene County Auditor 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 (Ohio counties operate a six-year reappraisal cycle with a triennial update; Greene County's most recent full reappraisal was 2023, with the next triennial update due in 2026) 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. Greene County also administers Current Agricultural Use Valuation (CAUV) under O.R.C. § 5713.30 - § 5713.38; the county has substantial CAUV-enrolled acreage, particularly in Jefferson, Silvercreek, Caesarscreek, Ross, and New Jasper townships in the eastern and southern parts of the county. An ADU on a CAUV parcel may trigger recoupment (a three-year rollback) if the dwelling reduces qualifying agricultural acreage below program thresholds. Under O.R.C. § 5713.17, the owner must notify the Auditor of any construction or improvement valued over $2,000. Board of Revision complaints (property-tax assessment appeals) for Greene County parcels are filed with the County Auditor between January 1 and March 31 each year. Greene County's tax base includes substantial commercial and industrial valuation from Wright-Patterson AFB (federal exempt, but supporting contractors and ancillary parcels are taxable), the Beavercreek shopping district along North Fairfield Road, Wright State University-area properties, and the residential growth in Sugarcreek Township along the Centerville-Bellbrook corridor.
County overlays (6)
Known county issues (6)
- other — ADU applicants in unincorporated Greene County benefit from shorter plan-review lead times than in counties without a certified building department, but face an additional zoning entity (GCRPCC) that does not exist in counties where all zoning is township-tier. Lead times for residential construction permits at the Greene County Building Regulations Department are commonly two to four weeks; BZA variances add 60-120 days on top.
- other — ADU projects on parcels in Bath Township, the eastern edge of Beavercreek Township, and northern Fairborn that fall inside an AICUZ APZ or above the 65 dB DNL noise contour face heightened review and may be denied or required to install noise-attenuation construction adding $10,000-$30,000 to project cost. Applicants should consult the published WPAFB AICUZ Study before site selection.
- other — ADU projects within the Little Miami riparian corridor or adjacent to Caesar Creek Lake should expect additional review steps adding 60-180 days and $2,500-$15,000 of consultant cost (riparian biologist, hydrologist, easement counsel) relative to a comparable unincorporated Greene County parcel outside these zones.
- other — Enumeration of Greene County cities here includes the cross-county Dayton entry for fidelity to the city-highlights tree, but consumers should not attribute Dayton's ~137,644 residents to Greene County. Greene County's wholly-resident incorporated population is dominated by Beavercreek (~48,000, not in the highlights enumeration), Fairborn (~33,452), Xenia (~25,976), and Bellbrook (~7,053) plus the smaller villages.
- other — Consumers reading summaryByLocale should be aware that the rollup includes only the two enumerated locales, not a comprehensive locale enumeration of all of Greene County's neighborhoods, districts, or unincorporated communities. As locale-adu-research files are added, the rollup will refresh to include their statistics.
- policy-review — Researchers should monitor the Ohio General Assembly for any future ADU preemption proposal. Until one passes, Greene County ADU permissibility is a parcel-by-parcel question driven by the applicable township or municipal zoning, county zoning resolution where applicable, and (for parcels near Wright-Patterson AFB or in the Little Miami / Caesar Creek corridors) the relevant environmental or AICUZ overlay review.
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.