5 Fire Code Terms to Know

Navigating the International Building Code and the International Residential Code—and the fire protection requirements within each—can be somewhat challenging, to say the least.

For architects and engineers who are familiarizing themselves with the current fire protection requirements systems, here are some of the key terms you'll come across:

• "Fire Code": Traditionally, the term "Fire Code" refers to the fire code determined by the National Fire Protection Association (NFPA) or the fire code from one of the legacy organizations that merged into the International Code Council, which generally applies to a building post-construction, after occupancy. In contrast, most builders are more concerned about the fire protection requirements within the International Building Code (IBC) and the International Residential Code (IRC), which largely dictate how the building is designed and built to prevent the spread of fire, such as fire walls.

"International Building Code": The IBC "establishes minimum regulations for building systems using prescriptive and performance-related provisions." Copyright is maintained by the International Code Council (ICC). "The International Building Code is kept up to date through a review of proposed changes submitted by code enforcing officials, industry representatives, design professionals, and other interested parties. Proposed changes are carefully considered through an open code development process in which all interested and affected parties may participate." New editions of the code are released every three years, with the most recent version dated 2015.

• "International Residential Code": The IRC is "a comprehensive, stand-alone residential code [that] establishes minimum regulations of one- and two-family dwellings and townhouses using prescriptive provisions." It is also maintained by the ICC. Changes to the code are considered through an open, participatory development process available at www.cdpACCESS.com. Updated versions of the IRC are released every three years, with the most recent version dated 2015. The IRC is designed for adoption by local jurisdictions, who can modify codes according to local needs.

Following the requirements of your locally adopted IRC is essential not only to ensure designs pass building inspections, but also to help ensure the longevity of homes and, most importantly, the safety of their occupants. 

• "UL": Underwriters Laboratories is a leading product safety testing organization. The company develops product safety testing procedures and certifies individual products under those tests. UL is a key player in the building code process because it acts as an independent third party. Buyers can be assured that products with the UL label have been tested by an outside entity with no financial stake in the product's sale.

• "Flame Spread Ratings": According to the IRC, flame spread is "the propagation of flame over a surface." The "flame spread index" is a comparative measure referenced several times throughout the code, including in the requirements for classification of fire-retardant wood and specification of insulation. Flame spread is measured in a "tunnel test" developed more than 70 years ago at Underwriters Laboratories. Materials are rated on a scale of 0 to 100; the lower the value, the lower the flame spread.

Class A, or 1, is defined as a value of 25 or less. These are almost always synthetic materials. Concrete has a value of 0. Fire-retardant-treated wood is required in Chapter 23 of the IBC to have a Class A rating.

Class B, or 2, is defined as a value of 26–75. Some naturally fire-resistant woods, such as redwood, fall into this category.

Class C, or 3, is defined as a value of 76–200.  Most wood materials fall into this category.

It is important to note that flame spread does not measure burn-through resistance. A material can have a Class A rating for flame spread and very little burn-through resistance.

• "Exposure 1": Per APA - The Engineered Wood Association, Exposure 1-rated panels "are intended to resist the effects of moisture due to construction delays, or other conditions of similar severity. Exposure 1 panels may also be used when exposure to the outdoors is on the under-side only, such as roof overhangs, although appearance characteristics of the panel grade should also be considered. Exposure 1 panels are made with the same exterior adhesives used in Exterior [rated] panels. However, because other panel compositional factors may affect bond performance, only Exterior panels should be used for long-term exposure to weather."