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Changes in Recent IBC Firestop Requirements

Sponsored Feature by Specified Technologies, Inc.

The majority of firestop installation is driven by the building codes as they establish a minimum level of safety that must be adhered to during the design and construction of new buildings. Arguably the most prevalent building code in the United States is the International Building Code, which is published by the International Code Council. The extensive degree of adoption of the IBC and its oversight of most building types means that those of us within the firestopping industry need to have a basic understanding of what changes exist between the most recent editions of the IBC. This article will focus on highlighting any requirements that changed for through penetrations, joints or curtain wall applications over the 2015, 2018 and 2021 editions of the IBC.

Through Penetrations

The need for firestopping at through penetration locations (see the photo on this page for examples of through penetrations for firestop in a wall assembly) is probably the easiest code requirement to understand because these requirements show the smallest degree of change over the three most recent editions of the IBC. If an opening has been made in a fire-rated assembly, then the through-penetration firestop is the material or device that seals that opening and prevents fire from passing through the assembly. The IBC splits requirements for penetrations in wall assemblies and horizontal assemblies into two separate sections. The 2018 and 2021 editions of the IBC have identical requirements for penetrants contained in walls, and this language can be found in section 714.4.1.2 of the code. Looking back at the 2015 edition shows that the same requirements are contained in section 714.3.1.2 for this earlier version of the IBC. What about the requirements for horizontal assemblies?

When we examine the firestopping requirements for through penetrants in horizontal assemblies across the three most recent editions of the IBC, it is apparent that once again the 2018 and 2021 versions are identical. The requirements for these two editions can be found in section 714.5.1.2 of the code. The appropriate section to reference in the 2015 edition does not match that of the 2018 or 2021 IBC and can be found in section 714.4.1.2. There is also a technical change that occurs between the 2015 and 2018 editions of the IBC that relates to the T Rating exceptions for penetrants in floor assemblies. The third exception concerning penetrants passing directly into electrical switchgear refers to these items as “maximum 4-inch (102 mm) nominal diameter” in the 2015 IBC. The requirements are more precise in the 2018 and 2021 editions of the code and reference “maximum 4-inch (102 mm) nominal diameter metal conduit or tubing.”

There are more significant changes for joint firestopping requirements compared to those for through penetration firestops across the three most recent editions of the IBC. This time the 2015 and 2018 editions are very similar. They each lay out what locations require a fire-resistant joint system and specify that the rating of these firestop systems must equal the fire rating of the joint substrates. This language is contained within section 715.1 of the IBC, which also contains a number of exceptions where fire-resistant joint systems are not required and a reference that points to section 715.3 of the code for the appropriate test standards to validate joints.

Fire-Resistant Joint Systems

The 2021 edition of the IBC differs in that section 715.1 now contains a general statement that outlines this section of the code governs the materials and methods that are necessary to protect joints. Section 715.3 of the 2021 IBC is then comparable to section 715.1 from the two earlier editions and speaks to what locations need a fire-resistant joint system (see photo above) and the required ratings of these joints. The 2021 edition of the IBC requires that fire-resistant joint systems be tested in accordance with either ASTM E1966 or UL 2079 in section 715.3.1, and these are the two standards allowed by the 2015 and 2018 editions of the IBC.

Therefore, while the presentation of joint requirements has been changed in the 2021 edition of the IBC, the test standards that the code mandates for joints, and locations that joint firestop systems are required, do not vary between the three most recent editions of the IBC.       

Perimeter Fire Containment Systems

As was the case for joints there are also some slight differences in the IBC requirements for perimeter fire containment systems (see photo on next page) in the 2021 edition relative to the two earlier editions of the code. While the 2015 and 2018 editions of the IBC are identical in their requirements for curtain walls, which are called out in section 715.4 and mandate testing in accordance with ASTM E2307, one of the major changes for 2021 is the introduction of the defined term “perimeter fire containment system.” The formal definition of this phrase is contained in Chapter 2 of the code and reads as follows, “an assemblage of specific materials or products that is designed to resist for a prescribed period of time the passage of fire through voids created at the intersection of exterior curtain wall assemblies and fire-resistance-rated floor or floor/ceiling assemblies.”

The 2021 edition of the IBC benefits from this clarification since the 2015 and 2018 editions simply refer to an “approved” system as the requirement for the firestop between a rated floor assembly and a curtain wall. This is also the same term that is used by UL to describe their listed curtain wall systems, and their Guide Information for the XHDG category has historically used this terminology. The other major change in the 2021 edition of the IBC is the creation of a subsection 715.4.1, which now contains the reference to ASTM E2307. This leads to an improved flow as section 715.4 instructs on what steps must be taken at the slab edge, and then 715.4.1 establishes how to meet these requirements.

It is important to understand the firestopping requirements of the IBC since this building code is typically the primary reason that firestops need to be installed within a new building. The IBC is revised over a three-year cycle, and accordingly there are sometimes modifications to the rules industry professionals need to follow in designing and constructing safe buildings in regard to firestop. However, these changes are typically incremental and if an individual has a base knowledge of the original code, then it is not much of a stretch to become familiar with the newly published edition of the code. Specified Technologies, Inc. stands ready to help and will be happy to explain any changing requirements and point to the code language relevant to firestopping. Visit

About the Author

David Vail, PE, is project manager and monitors codes and standards for Specified Technologies, Inc.

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