Spray foam insulation serves as an alternative to more traditional building insulation material such as fiberglass. Due to its ease of application and effective insulating properties, it is often specified for use in concealed spaces such as attics or cavity spaces. The use of spray foam insulation within buildings, however, has implications that must be addressed from not only the perspective of the building code, but also NFPA 13 Installation of Sprinkler Systems.
Per the International Building Code (IBC), when spray foam insulation is installed within a building it is required to be separated from the building interior by means of a thermal barrier or ignition barrier, except for specific exempt situations (2015 IBC 2603.4). This is often achieved by encasing the foam in an intumescent paint tested via NFPA 275 Standard Method of Fire Tests for the Evaluation of Thermal Barriers; however, the presence of a barrier is not required if the materials themselves have been tested (in the manner intended for use) in accordance with NFPA 286 Standard Method of Fire Test for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth, FM 4880 Approval Standard for Class 1 Fire Rating of Insulated Wall or Wall and Roof/Ceiling Panels, Interior Finish Materials or Coatings and Exterior Wall Systems, UL 1040 Fire Test of Insulated Wall Construction, or UL 1715 Fire Test of Interior Finish Material (2015 IBC 2603.9). The primary intent of these provisions of the IBC is to delay involvement of the foam material in a fire.
NFPA 13, on the other hand, addresses scenarios where concealed spaces which contain combustible materials or surfaces (such as spray foam insulation) are exempt from sprinkler protection. The 2013 edition of NFPA 13 (currently adopted in the Commonwealth of Massachusetts) allows for omission of sprinklers in such concealed spaces where “…rigid materials are used and the exposed surfaces have a flame spread index of 25 or less, and the materials have been demonstrated not to propagate fire more than 10.5 feet when tested in accordance with ASTM E84 The Standard Test Method for Surface Burning Characteristics of Building Materials or ANSI/UL 723 Standard for Test for Surface Burning Characteristics of Building Materials, extended for an additional 20 minutes…” (2013 NFPA 13-188.8.131.52.10).
What is important to note is that the NFPA criteria to omit sprinklers within a concealed space which contains spray foam insulation are different than the basic IBC criteria for mitigation of the foam within the same space. As such, while a particular product may be adequate to demonstrate compliance with IBC Chapter 26 provisions, it must be further verified that the product also satisfies NFPA 13 requirements if sprinklers are to be omitted from the space.
In order to facilitate compliance with the provisions of NFPA 13, the corresponding section of the 2019 Edition of NFPA 13 (not yet adopted in the Commonwealth of Massachusetts) has been modified to allow two options for omission of sprinklers in such concealed spaces (2019 NFPA-13 184.108.40.206):
- Rigid materials that have a flame spread index of 25 or less, and not propagate fire more than 10.5 feet when tested in accordance with ASTM E84, extended for an additional 20 minutes; or,
- Rigid materials that comply with the requirements of ASTM E2768 Standard Test Method for Extended Duration Surface Burning Characteristics of Building Materials.
The newly referenced ASTM E2768 test is comparable to the ASTME E84 test, except that it has a standard duration of 30 minutes and thereby allows for a clearer way to demonstrate and document compliance with these provisions.
Over time, it is expected more products will be tested against ASTM E2768, making it easier to comply with the NFPA criteria. In the meantime, products currently tested per ASTM E84 can still be used provided the manufacturer is able to furnish documentation demonstrating adequate performance during an extended ASTM E84 test. When selecting and reviewing products, its important to be aware of the above requirements for both the IBC and NFPA 13 in order to solicit and verify the correct testing data from a product manufacturer.
One additional consideration is the definition of “rigid materials”, as used above in the context of concealed spaces in NFPA 13. Determination of what constitutes “rigid material” can be subjective, especially in the context of foam materials. Ultimately the interpretation of the definition is subject to the discretion of the Authority Having Jurisdiction and the Registered Design Professional based on the proposed products and specific applications.
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