Where a cold-formed steel frame building does not satisfy the scope limits of the 2024 IRC, the fire-safety provisions of the 2024 IBC must be used. In addition to all other basic fire-safety requirements in the IBC (e.g., Chapters 3-10) and requirements for exterior walls (Chapter 14) and roofs (Chapter 15), specific requirements for use of FPIS are found in Chapter 26, particularly Section 2603.  

In accordance with IBC Chapter 6, (and where not otherwise limited in IBC Chapter 4 based on occupancy and use of a building), cold-formed steel construction can be used for buildings that comply with various applicable construction classifications or “construction types” as described in IBC Chapter 6. A given construction type for a building project also requires that the building comply with the building height and area limits and other requirements of IBC Chapter 5 related to that construction type. 

For example, if a cold-formed steel frame wall is used in a Type V building (allowing the use of any construction material permitted by the code per IBC Section 602.5), the building height and area limits must comply with the more restrictive requirements for Type V construction in IBC Chapter 5 and this then allows use of the less restrictive assembly fire resistance rating requirements for Type V construction in IBC Chapter 6. It also has less restrictive requirements for use of combustible materials in IBC Chapter 14 Exterior Walls and in IBC Chapter 26 Section 2603 for use of FPIS. 

On the other hand, if a cold-formed steel frame wall is used in a building occupancy and use (see IBC Chapter 4) that does not permit the application of Type V construction or is used in a building that exceeds the height and area limits of Type V construction (see IBC Chapter 5), then the building and its exterior walls must be designed to comply with a different construction type. For many cold-formed steel frame buildings that don’t meet the Type V construction limitations and requirements, the applicable construction type is Type II which requires use of noncombustible materials per IBC Section R602.2. However, IBC Section R603 permits the use of combustible materials in Type I and Type II construction under specific conditions.  For example, foam plastics like FPIS are permitted provided they comply with IBC Chapter 26.  

Consequently, IBC Section 2603 requirements for specification and use of FPIS ci on or in building assemblies depend on the applicable construction type of the building as discussed above. The key requirements are summarized as follows:

General Requirements for All Building Construction Types:
  • Foam Plastic Materials and Standards – refer to IBC Section 2603.1.
  • Labeling and identification – required on materials or packaging; refer to IBC Section 2603.2.
  • Surface burning characteristics – required; maximum flame spread index and smoke-developed index of 75 and 450, respectively (with various exceptions); refer to IBC Section 2603.3.
  • Thermal barrier – required; typically not less than ½-inch-thick gypsum wallboard on interior side of wall or assembly tested per NFPA 275 (with various applications and conditions where thermal barrier is not required); refer to IBC Section 2603.4.
  • Roofing – foam plastic insulation meeting the above requirements is permitted as part of a roof covering assembly (e.g., above-deck roof insulation) where the roof assembly with the foam plastic insulation is a Class A, B, or C roofing assembly per ASTM E108 or UL 790; refer to IBC Section 2603.6 and Section 1505 where the required fire classification depends on the building’s construction type.
For Type I, II, III, and IV Construction:  
  • Exterior Walls of Buildings of Any Height – In addition to the general requirements addressed above, IBC Section 2603.5 addresses specific requirements for use of foam plastic insulation on exterior walls of Type I, II, III, and IV buildings of any height (with a few exceptions). These requirements do not apply to Type V construction or other assemblies on a Type I, II, III, or IV building.  In general, data to demonstrate compliance with these provisions is obtain directly from FPIS manufacturers (see DESIGN RESOURCES and CONSULT MANUFACTURER DATA below). For convenience, the requirements of Section 2603.5 are characterized as follows:
    • Section 2603.5.1 – Where required, the wall shall have a fire-resistance rating based on tests per ASTM E119 or UL 263.
    • Section 2603.5.2 – A thermal barrier is required per Section 2603.4 unless special approval is obtained per Section 2603.9.
    • Section 2603.5.3 – The potential heat of the foam plastic insulation used in the wall must not exceed the potential heat of the foam plastic insulation contained in the wall assembly tested per Section 2603.5.5.
    • Section 2603.5.4 – The flame spread index of the foam plastic insulation must not exceed 25 per ASTM E84 or UL 723.
    • Section 2603.5.5 – The vertical and lateral fire propagation of the exterior wall assembly must be tested and comply with the acceptance criteria of NFPA 285.  
    • Section 2603.5.6 – A label by an approved agency is required on each piece, package or container of foam plastic insulation that identifies the material, manufacturer, and performance characteristics, among other things.
    • Section 2603.5.7 – Exterior walls shall not exhibit sustained flaming where tested in accordance with NFPA 286 (with exceptions for assemblies protected on the outside by various materials).

DESIGN RESOURCES: For additional information on fire safety compliant design of exterior wall assemblies with FPIS-ci, refer to fire performance and these DrJ Research Reports: 

IMPORTANT TIP: 

FPIS manufacturers often conduct special code-compliance fire testing on their products IBC Section 2603.9 Special Approval to take advantage of the fire performance features of their specific FPIS products or assemblies. These may provide more efficient solutions, such as allowing use of FPIS without a separate thermal barrier or ignition barrier in certain applications.

CONSULT MANUFACTURER DATA: For product specific data and manufacturer support related to fire safety, refer to this listing of FPIS manufacturers.

NEXT STEP: With fire-safety decisions of STEP 2 addressed by specification of the FPIS material properties and other components of the wall assembly (e.g., thermal barrier) applicable to Type V construction, proceed to STEP 3.

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