Draftstop Req'd In Omitted Concealed Spaces?

We have a residential R-2 occupancy, four-story, combustible Type V-B, new construction building with an NFPA 13 system. The floor/ceiling assemblies are built with open-web wood trusses. 

All of the interstitial spaces around these trusses are to be filled with non-combustible insulation, which allows sprinklers to be omitted within them in accordance with NFPA 13-2013 8.15.1.2.7 "concealed spaces filled with noncombustible insulation shall not require sprinkler protection."

The IBC (2015) requires drafstopping in combustible construction to "subdivide floor ceiling assemblies" above an in-line with dwelling unit and sleeping unit separations (IBC 2015 718.3.2). However, an exception exists for buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 (an NFPA 13 system).

If these spaces omit sprinklers due to non-combustible insulation, is draftstopping still required per the IBC?

​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe