New Hampshire officially adopted the 2015 International Residential and Building Codes (IRC, IBC) in September, 2019. The State Legislature amended the IRC by delaying enforcement of Section 302.13, Fire Protection of Floors, for 18 months. That delay has expired, and Section 302.13 is applicable as of March 15, 2021.
IRC 2015 Section 302.13 requires that floor structures now be constructed in one of several specific ways to further prevent vertical spread of fire. The APA, representing the engineered wood industry, published System Report SR-405 to provide prescriptive construction techniques for floors specifically constructed with I-joists. There are multiple ways to construct I-joists floors to meet these provisions, including approaches that do not require a gypsum board ceiling. More specifically, these techniques provide “other approved floor assemblies demonstrating equivalent fire performance” in exception 4. The document also includes provisions for construction openings in the joist webs.