General Exterior Code Requirements in Ohio

State with significant severe hail frequency per NOAA SPC storm reports. Insurance restoration contractors should document pre-existing hail damage and recommend impact-resistant materials.

Over 900 Ohio communities participate in the National Flood Insurance Program (NFIP). NFIP participation requires adoption and enforcement of floodplain management regulations. Flood insurance is available only in participating communities. Ohio Department of Natural Resources coordinates state floodplain management.

Areas with historical underground coal mining operations where subsidence risk exists. Primarily affects eastern Ohio counties including: Belmont, Jefferson, Harrison, Tuscarawas, Columbiana, Carroll, Perry, Athens, and other counties in the Appalachian coalfield region. Ohio has extensive underground mining history dating to the 1800s.

Coastal erosion management area along Ohio's 312-mile Lake Erie shoreline. Affects coastal portions of Lucas, Ottawa, Sandusky, Erie, Lorain, Cuyahoga, Lake, and Ashtabula counties. Subject to wave action, shoreline erosion, high water levels, and coastal storms. Ohio Coastal Management Program administered by ODNR Office of Coastal Management.

Areas with limestone and dolomite bedrock prone to dissolution, creating sinkholes, caves, and underground drainage. Primarily located in western Ohio counties including: Adams, Highland, Clark, Champaign, and portions of Greene and Warren counties. Ohio has over 3,500 mapped karst features.

Ohio has extensive flood hazard areas along major rivers: Ohio River (entire southern border), Scioto River, Great Miami River, Muskingum River, Cuyahoga River, and numerous tributaries. These corridors have detailed FEMA flood studies with base flood elevations.

Many Ohio communities require freeboard (additional elevation above BFE). While NFIP minimum is at-or-above BFE, many Ohio communities require 1-2 feet of freeboard for additional protection. Check with local floodplain administrator for specific requirements.

The majority of Ohio counties fall within EPA Radon Zone 1 with predicted indoor screening levels above 4 pCi/L. Glacial till deposits overlying Ohio Shale and Devonian-age bedrock are primary radon sources. Central and western Ohio have the highest concentrations. IRC R324 radon-resistant new construction is recommended statewide. Ohio Department of Health maintains county-level radon data and testing programs.

Ohio experiences 15-20 tornadoes annually, concentrated from April through July. The western Ohio corridor (Auglaize, Mercer, Darke, Miami counties) has the highest tornado density. The 2019 Memorial Day Dayton tornado outbreak produced multiple EF3-EF4 tornadoes. Enhanced wind design per ASCE 7-22 and safe room provisions per FEMA P-361 are recommended for new residential construction in western Ohio.

Northeast Ohio counties including Ashtabula, Lake, Geauga, and Cuyahoga experience lake effect snow from Lake Erie with seasonal totals exceeding 100 inches. Chardon (Geauga County) averages 106 inches annually. Ground snow loads per ASCE 7-22 reach 25-35 psf in the snowbelt. Roof structures must be designed for asymmetric loading from wind-driven lake effect bands.

Ohio frost depths range from 24 inches in southern counties to 42 inches in the northeast snowbelt. Ashtabula, Geauga, and Lake counties have the deepest frost penetration due to sustained cold and moisture from Lake Erie. Foundation footings must extend below the local frost line per IRC R403.1.4. Most Ohio jurisdictions require 36-inch minimum footing depth.

Western and central Ohio contain extensive glacial lake clay deposits (from glacial Lake Maumee and Lake Erie predecessors) that are moderately to highly expansive. Lucas, Wood, Hancock, and Wyandot counties have the most problematic soils. Foundation design per IBC 1808.6 should account for shrink-swell potential. Geotechnical investigation is required in areas mapped with high-plasticity glacial clays.

Ohio has over 200 National Register historic districts including German Village and Victorian Village (Columbus), Ohio City and Tremont (Cleveland), Over-the-Rhine (Cincinnati — one of the largest in the US), and Oregon District (Dayton). Restoration work in these districts may require Ohio Historic Preservation Office review and compliance with Secretary of Interior Standards. Local historic preservation commissions enforce design standards.

Ohio has two seismically active regions: the Northeast Ohio Seismic Zone (Lake-Geauga-Ashtabula counties) and the Anna Seismic Zone in southwestern Ohio (Shelby-Auglaize counties). The 1986 Northeast Ohio earthquake (magnitude 5.0) and induced seismicity near Youngstown (2011-2012) from wastewater injection highlight ongoing risk. Seismic Design Category A-B applies per ASCE 7-22.

Ice barrier underlayment is REQUIRED statewide per Ohio Building Code (ORC 3781, IRC R905.1.2). Ohio spans Climate Zones 4A (southern) and 5A (central/northern). Mean January temperatures range from 28°F (southern) to 24°F (northeast/lake effect zone). Northern Ohio receives 40-100+ inches of snow annually.

Areas designated as Zone A, AE, V, or VE on FEMA Flood Insurance Rate Maps. Ohio has significant riverine flood risk along the Ohio River, Muskingum River, Scioto River, Great Miami River, and other major waterways. Lake Erie coastal areas also subject to flooding and wave action. Local jurisdictions participate in National Flood Insurance Program (NFIP).

Ohio requires preservation of regulatory floodways. Development in floodways is severely restricted. Any encroachment that would increase flood heights is prohibited. Floodway is the channel plus adjacent floodplain needed to convey the base flood.