ADU Pass
Franklin County
ADU Pass helps homeowners in Franklin County, Ohio navigate the permit paperwork for building an accessory dwelling unit. We cover 14 cities and 65 ZIP codes in this county.
Map
County ADU details
County ADU ordinance
Franklin County (state-capital county; ~1,326,000 residents — Ohio's most populous county; encompassing Columbus, Westerville, Dublin partial, Worthington, Bexley, Whitehall, Reynoldsburg, Gahanna, Hilliard, Upper Arlington, Grove City, Grandview Heights, New Albany, Pickerington partial, Canal Winchester partial, and a substantial fraction of unincorporated Franklin in townships including Sharon, Norwich, Washington, Madison, Truro, Hamilton, Mifflin, Plain, Blendon, Clinton, Perry, Pleasant, Brown, Jefferson, Franklin, Prairie, Jackson, and Marion) regulates land use in unincorporated areas through township-tier zoning under Ohio Revised Code Chapter 519 (Township Rural Zoning). Ohio is a Dillon's Rule state with home-rule for charter municipalities under Ohio Const. Art. XVIII. Counties may not directly zone unincorporated areas in Ohio (with exceptions for Lake County and a few others); zoning in unincorporated Ohio is performed by the township under ORC 519, with county Planning Commissions providing advisory review. Franklin County's Economic Development and Planning Department coordinates planning across the county and provides advisory review of township zoning under ORC 519.04. ADU regulation in Franklin County is therefore primarily township-tier and city-tier; the County's role is limited to advisory planning, the Franklin County Auditor (assessment), the Franklin Soil and Water Conservation District, and the Franklin County Public Health for septic permitting.
County assessor
Assessment policy: Franklin County Auditor (Ohio uses elected County Auditors as the property-assessment authority under ORC § 5713.01) assesses real and personal property. Ohio assesses property at 35% of true value (ORC § 5713.03). New ADU construction is reassessed at true value as of January 1 following completion. Ohio's Owner Occupancy Credit (ORC § 323.151 et seq.) provides 2.5% reduction in tax bill on owner-occupied homestead; the Homestead Exemption (ORC § 323.151) provides $25,000 of property value off taxable value for owners 65+ or disabled (income-qualified). An ADU rented separately may carve out a non-homestead component subject to standard assessment.
County overlays (3)
Known county issues (3)
- other — ADU researchers in unincorporated Franklin County must look to township-tier zoning (Sharon, Norwich, Washington, Madison, Truro, Hamilton, Mifflin, Plain, Blendon, Clinton, Perry, Pleasant, Brown, Jefferson, Franklin, Prairie, Jackson, Marion). The county role is limited to advisory planning and assessment.
- other — Most Franklin County ADU activity flows through Columbus's expanded city-tier framework; township rules are more conservative.
- other — Some unincorporated west-Franklin parcels (Plain, Brown, Pleasant, Madison, Jackson townships within the Accord) face development constraints that affect ADU siting and design.
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.