What requires a permit, what is exempt, and how the Residential Code of Ohio applies to outdoor living projects in Union County — Marysville, Plain City, Jerome Village, and Dublin's Jerome Township side. Reviewed August 2026.
Ohio's Residential Code (RCO) sets the baseline: permits are required for attached decks, roofed structures, and detached buildings of 200 square feet or more — one-story detached accessory structures under 200 square feet are exempt, including from frost footings. Pools holding more than 24 inches of water require a permit and a 48-inch barrier under Ohio Revised Code 3781.102, with self-closing, self-latching gates latched at least 54 inches above grade. Union County's building office serves most of the county, with Marysville and Dublin handling their own portions — the parcel decides which one, and in Jerome Village and the newer developments, HOA architectural review runs alongside the permit.
At-grade paver and concrete patios are flatwork — generally no building permit, though setbacks, drainage, and HOA review apply in the newer developments. Anything structural bears below Ohio's 32-inch frost line, and retaining walls over four feet from the bottom of the footing typically require a permit and engineering.
Attached decks require a permit and inspections — frost-depth footings, ledger attachment, and guardrails. A detached one-story accessory structure under 200 square feet is exempt; a pavilion or pergola built for living space, attached to the home, or carrying electrical, gas, or a motorized louvered roof should be planned as permitted, engineered work. Allscape submits stamped engineering with every motorized pergola application.
The short version of Ohio's rules for the three most common outdoor living projects. Confirm specifics with the county or your city — requirements are finalized at plan review.
No building permit for at-grade flatwork in most cases. Setbacks, drainage, and HOA review apply. Retaining over four feet triggers engineering; structural elements bear below the 32-inch frost line.
Attached deck: permit required. Detached one-story structure under 200 sq ft: exempt, even from frost footings. Occupied, attached, or motorized structures: permitted, engineered work.
Permit required over 24 inches of water depth — plus a 48-inch barrier with self-closing, self-latching gates latched at 54 inches, per Ohio Revised Code 3781.102.
Union County including Marysville, Plain City, Milford Center, and Jerome Township — Jerome Village and the Union County side of Dublin. Allscape confirms the right permit office before submission.
