ADU Rules in Columbus, OH (2026)

Columbus, OH permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law governs the approval process. In Columbus, the Columbus Building and Zoning Services handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Columbus.

ADU Size Limits

ADU Size Limits in Columbus: Detached ADU: up to 800 sq ft (max height: 20 feet). Attached ADU: Up to 33% of primary dwelling floor area. Columbus City Codes Chapter 3332 — Accessory dwelling units limited to 800 sqft for detached units, or 33% of primary dwelling gross floor area for attached/internal units. Columbus does not use the California JADU terminology. Maximum lot coverage limits by zone apply — ADU floor area counts toward lot coverage calculation.

Permit Fees

ADU Permit Fees in Columbus: Plan check fee: $200–$800. Building permit fee: $500–$2,500 based on construction value. Impact fees: None. School fees: None or N/A. Total estimated permit cost: $1,000–$4,500 total fees. Columbus does not impose development impact fees or separate school fees. Building permit fees based on construction valuation per Columbus fee schedule. Columbus Public Utilities may charge water/sewer connection fees for ADU new connection. No impact fees — a competitive advantage for ADU development compared to western cities.

Permit Timeline

Columbus ADU Permit Timeline: Columbus Building and Zoning Services processes permits. Typical timeline: 3-6 weeks for zoning review, 2-4 weeks for building permit. Columbus Citizen Access Portal (columbuscitizenaccess.org) for online permit applications. Complex ADU projects may require pre-application meeting. Apply through the Columbus Building and Zoning Services online permit portal. Phone: (614) 645-7433.

Setback Requirements

ADU Setback Requirements in Columbus: Front setback: follows zone standard. Side setback: 3 feet. Rear setback: 5 feet. Columbus City Codes Chapter 3332. Detached ADUs require 5 ft rear setback and 3 ft side setback. Alley-loaded lots allow reduced rear setback (5 ft from alley right-of-way). Detached ADU must maintain at least 6 ft clearance from primary dwelling. Columbus has extensive alley network in older neighborhoods providing rear access for ADU placement.

Parking Requirements

Parking Requirements: 1 space per ADU unless located within 1/4 mile of a COTA fixed bus route. Columbus Area Transit Authority (COTA) bus network is extensive — many residential properties qualify for parking reduction. Alley-side garages can satisfy parking requirement.

Restrictions & Requirements

• •Maximum one ADU per single-family lot in R-1, R-2, R-3 zones
• •ADU must be on same lot as primary single-family dwelling
• •ADU cannot be separately conveyed or sold apart from the primary lot
• •Total impervious coverage limits by zone apply
• •ADU must have separate entrance independent from primary dwelling entrance
• •Alley access strongly encouraged for rear-yard ADU placement

How Many ADUs Are Allowed?

Number of ADUs Allowed in Columbus: Single-family lots: 1. Multifamily properties: Additional units permitted in AR zones per base density. Columbus allows one ADU per single-family lot in R zones. Columbus explored expanded ADU provisions in 2023-2024 as part of housing supply initiatives. Columbus 2050 Plan supports ADU expansion as affordable housing strategy.

Historic District Considerations

Frequently Asked Questions