Ohio puts a steel container through cold winters and humid summers, so an insulation plan has to manage moisture as well as heat.
Ohio's residential energy rules are based on the 2018 International Energy Conservation Code with state amendments, effective July 1, 2019, according to the U.S. Department of Energy's Ohio status page. In that code's county table, Adams, Brown, Clermont, Gallia, Hamilton, Lawrence, Pike, Scioto and Washington counties are Climate Zone 4A. Every other Ohio county, including Franklin, Cuyahoga and Lucas, is Zone 5A.
Because Ohio amended the model code, the insulation values in a national chart may not be the ones your building department enforces. Ask the department for the requirement that applies to a conditioned container before you buy materials. Commercial buildings follow the 2021 IECC and ASHRAE 90.1-2019, effective March 1, 2024, according to the same page.
Steel moves heat quickly. On a winter night, the inside face of an uninsulated wall or roof drops close to the outdoor temperature, and warm, damp air inside, from breath, wet boots or a heater, condenses on it and drips. In summer, warm, humid air that reaches a cooler surface, such as the steel of an air-conditioned container, can condense the same way. Moisture, more than cold, is what ruins stored goods and finishes.
Insulation that leaves an air gap against the corrugated steel gives moisture a hidden cold surface to collect on. Closed-cell spray foam applied directly to the steel is one way to avoid that gap, and rigid foam fully adhered to the steel with sealed seams is another. The right assembly depends on the use, the fire protection the building department requires, the wiring route and the interior finish, so have a qualified designer specify it for any conditioned space.
The roof takes summer sun and winter snow, and the floor sits over cold, damp ground. Lake-effect snow adds load in the snowbelt south and east of Lake Erie. During one event that began on Thanksgiving Day 2024, the National Weather Service office in Cleveland reported snow totals above three feet in parts of extreme northeast Ohio and northwest Pennsylvania. A converted container's roof needs a snow plan as well as insulation, and its floor needs a drained base so ground moisture and splashback stay off it.
Plain storage does not need insulation to work. It needs a level, drained base, contents kept off the floor and away from the walls, vents if the contents are sensitive to damp, and a check of the door gaskets and the roof each spring.
Insulation hides the steel, so a container you plan to insulate should start out watertight. Container One's FAQ describes One-Trip units as almost brand new, used once to ship from the factory to the U.S. They carry a 10 year structural and 10 year no-leak warranty. Cargo Worthy and Wind and Water Tight units carry 5 year structural and 5 year no-leak terms, and Economy units carry 1 year against roof leaks. In Toledo on October 14, 2026, a delivered 20ft started at $1,988 for Wind and Water Tight and at $3,021 for One-Trip.
Plan the delivery around the ground as well as the building. The same FAQ asks for 110 feet of straight, unobstructed space for a 20ft container and 130 feet for a 40ft, with at least 15 feet of height to drive, 22 feet of height along the entire unloading path and 10 feet of width. A gravel lane that holds a loaded truck in August can rut during the spring thaw, and the clay flats of northwest Ohio's old lake bed drain slowly. Clear snow from the route and the landing spot before the truck arrives.
This is general building-science information, not a design specification.