We have a hotel that is constructed with 12-inch TJI joists (composite engineered wood joists which have a continuous web, not an open web). There are gypsum ceilings attached directly to the bottom of the TJI joists. There is also at least 3.5-inches of insulation above the gypsum ceilings.
Are we required to calculate 3,000 sqft or 8 residential sprinklers, or do we meet the noted code exception below?
NFPA 13-2019 184.108.40.206.5.2(4) Item (10): Light or ordinary hazard occupancies where noncombustible or limited-combustible ceilings are attached to the bottom of composite wood joists either directly... , provided the adjacent joist channels are firestopped into volumes not exceeding 160 cubic ft, using materials equivalent to 1/2-inch gypsum board, and at least 3-1/2 inches of batt insulation is installed at the bottom of the joist channels when the ceiling is attached utilizing metal channels.
What are the "adjacent joist channels"?
And does the construction we have equal the firestopping as noted?
Does the gypsum ceiling attached to the bottom equal the firestopping, or is the firestopping something additional?
Roland Huggins wrote a good article on this issue, but I'm still not sure.
I have another senior tech convinced that this section is referring to an "unprotected" or non-firestopped combustible concealed space.
Thanks in advance.
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