Understanding the Building Code in Ohio

Clients often come to us unsure of how building codes work to help protect the public. Our job as designers includes finding ways to achieve the client’s goals while meeting these safety requirements. Building codes can be difficult to navigate, and the rules change over time, with significant revisions like the 2024 Ohio Building Code (and its companion, the new Ohio Existing Building Code).

THE BASIC FRAMEWORK

To understand how codes affect your project, it helps to know the basic framework. The Ohio Building Code (OBC) covers most buildings, while the Residential Code of Ohio (RCO) specifically applies to residences with one to three dwelling units. The OBC does include sections about residential spaces, as some buildings with living spaces don’t fall under the RCO. This article focuses on the OBC, which is sometimes called the ‘commercial’ building code.

The building code starts by categorizing buildings (or sections of buildings) according to three things: what they’re used for, what materials they’re built with, and their size. These classifications then determine which other requirements apply. For example, how a building is used will determine how many people are expected inside, which then dictates how many bathrooms and exit doors are needed. The code uses the word “occupancy” as a general category, with each occupancy group including several related specific “uses,” and different criteria apply to the various occupancies.

The building code’s occupancy groups reflect differences in how familiar occupants are expected to be with the space and their capacity to respond properly in an emergency. In places like concert halls or restaurants (Assembly occupancies), most visitors don’t know the building well and need more guidance. In office buildings (Business occupancies), workers are there regularly and understand their surroundings better. In places like prisons, hospitals, or daycares (Institutional occupancies), people may know the building well but can’t act independently. Prisoners, patients confined to beds, or young children all need help from others to evacuate during an emergency.

Building materials are classified by how flammable they are and how easily they transfer heat or fire throughout the building. Fire ratings measure how long materials can resist fire spread, expressed in hours or minutes. Individual parts (like doorframes) and complete systems (like specific wall designs) receive these ratings after testing by independent agencies. To qualify for various “Construction Types,” certain building components must meet minimum fire resistance times. This material classification is a factor in determining how large the building can be.

Each combination of building use and construction type has a maximum allowed floor area. This limit can be increased if the building uses sprinklers or enough open yard space around it for fire department access. Sometimes a building is already too large, or could become too large after a planned addition. In these situations, adding sprinklers might increase the allowed size. Another approach is to build a fire wall that effectively turns one large building into two (or more) separate buildings, each within the size limit.

In the cased of a mixed-occupancy building, the code allows the designer to declare whether those occupancies are separated or not, with fire ratings for the walls and/or floors that act as fire separation. With separation, designers can calculate maximum allowed size proportionally based on how much space each use takes up on each floor. Without separation, the entire building must follow the strictest size limit of any use occurring therein. When the code mentions sprinklers ‘throughout the building,’ this can mean that if one part of a mixed-use building needs sprinklers, they might be required everywhere—even in areas with uses that wouldn’t normally need them, regardless of fire separation.

BEYOND LIFE SAFETY

Besides regulating a building’s use, materials, and size, codes and the permit process also address Accessibility and Energy Efficiency. Accessibility primarily means complying with the Americans with Disabilities Act (ADA) to ensure buildings are usable by people with disabilities.

The Americans with Disabilities Act (ADA) became law in 1992, with specific design requirements outlined in the ADA Accessibility Guidelines (ADAAG). Though separate from building codes, these rules are enforced during permit reviews under the Ohio Building Code. Ohio applies the stricter ICC A117.1 standard, which covers most ADA requirements but with some higher standards—for example, requiring wheelchair turning spaces to be 67 inches across instead of the ADA’s 60 inches. New buildings must meet the current ICC A117.1 standard, while existing buildings may follow earlier versions.

Some buildings have accessibility features that don’t meet today’s standards because they were built before the ADA passed, or built before the 2010 updates to the guidelines and they have not been updated. In our experience, the most common accessibility problems in existing buildings include undersized toilet stalls with inadequate clearances, missing grab bars and handrails, changes in floor level without ramps, and doors that are too narrow or don’t have enough clear space around them.

Energy Efficiency focuses on how well the building’s insulation (the thermal envelope) and heating/cooling systems conserve energy. Energy efficiency standards have become stricter with each code update, to help buildings use less energy. The code sets minimum insulation values (R-values) for insulation between wall studs (cavity) and insulation that covers the exterior wall surface (continuous). These two types can be combined, or if you’re only using cavity insulation, a higher R-value will be required because the wall studs create thermal bridges that reduce overall performance. These requirements affect how thick walls must be, impacting design choices. Similarly, stricter roof insulation standards now require more overhead space, typically resulting in taller roof structures.

A CODE FOR EXISTING BUILDINGS

Ohio introduced its first standalone Ohio Existing Building Code (OEBC) in 2024, replacing what was formerly Chapter 34 in the main building code. This dedicated code governs renovations of, and additions to, existing buildings. Some sections override similar rules in the main code, while others specifically require compliance with certain parts of the main code. This means that when working on existing buildings, you should begin by checking the OEBC, though you’ll need to consult both codes to ensure full compliance.

Making code research more challenging, the OEBC offers three different ways to demonstrate compliance. The Prescriptive approach applies sections of the main building code to new or changed spaces, with certain exceptions—like reduced accessibility requirements and no need to meet energy efficiency standards. The Work Area approach lets you define specific areas in the renovated building that can follow less stringent requirements than the main code. The Performance approach evaluates the entire building using a scoring system, allowing trade-offs where strengths in one area can offset weaknesses in another. This method requires a thorough review of all building systems, including heating/cooling and other aspects covered by separate codes like the Ohio Mechanical Code. Without detailed analysis, it’s difficult to know which approach is best for your project. If the owner requests a comparison of the relative benefits of each compliance approach, this will make code research more time-consuming. There is an incentive to use the Prescriptive approach by default unless another method offers obvious savings. Building owners should understand these different compliance options.

The Ohio Existing Building Code requires accessibility features meeting the same ICC A117.1 standards, but includes provisions that can reduce renovation expenses. Most significantly, it caps the required spending for improvements to create an accessible route at 20% of the total project budget and provides a priority list for these improvements. Projects must first ensure an accessible entrance, then create accessible paths through the building, then address accessible restrooms and drinking fountains, before moving to lower-priority items.

Another helpful exception in the OEBC allows a single unisex accessible restroom when existing bathrooms can not be reasonably modified, whereas the main code requires restrooms for each sex to be accessible. Generally, accessibility is required only to the extent the change is “technically feasible,” meaning minor dimensional shortcomings don’t need expensive overhauls. However, you still need to install whatever accessible features you can—like using a shorter grab bar when there’s not enough space for a full-length one.

AVOID THESE PITFALLS

Don’t begin construction work without a permit. While you might think some projects don’t need permits, it’s best to check with your local building department—the requirements may be broader than you expect. To apply for a permit, you’ll generally need to submit forms, pay fees, describe your project, and provide drawings. Commercial building construction documents must be signed and stamped by a licensed design professional.

Understand the terminology of the permit process. A Building Permit is your official approval to start construction, issued after the building department reviews your plans for code compliance. As you build, the department conducts Inspections to make sure the work follows the approved plans. When construction is finished and passes the Final Inspection, you’ll receive a Certificate of Occupancy that legally allows people to use the renovated or new building.

When you want to use a building for a different purpose than its original use, you’ll likely need to submit the project as a Change of Occupancy. This can trigger stricter code compliance than other renovations, in which existing conditions are allowed to remain as-is unless they have been deemed to endanger public safety and welfare. With a Change of Occupancy, you must submit plans for review even if you’re not changing any walls or doors. You’ll need to show, at minimum, that life safety elements like exit signs, emergency lights, and fire alarm pulls meet current code requirements.

Make sure fire ratings are accessible to inspectors. Individual components like fire doors typically have factory-attached labels showing their rating—don’t cover or paint over these labels. For wall and floor assemblies, the design may be based on a specific tested reference assembly that requires particular brands and types of materials (such as specific gypsum board products). Using alternative materials not included in the tested assembly could lead to failed inspections unless you conduct your own testing to verify equivalent performance.

When you understand that public safety is the core purpose of building codes, the various classifications and requirements make more sense. Your project should be evaluated by a qualified design professional who can determine what changes are needed to meet code requirements. Childress & Cunningham strives to develop drawings that are clear in their approach to code compliance.