jar546
Forum Coordinator
For those of you who just updated to the 2021 IBC, there has been a modification to Table 1604.5.
Mixed occupancy buildings with assembly spaces are now designated as Risk Category III when the total public assembly occupant load is greater than 2,500 people.
CHANGE SIGNIFICANCE: Group R-1 hotels often have convention center facilities with multiple large ballrooms and other assembly spaces, but public assembly is not the primary occupancy of the building. These buildings have historically been classified as Risk Category II. Conversely, there are smaller buildings consisting solely of one or more assembly rooms where the primary occupancy is public assembly with a cumulative occupant load of over 300 that must be designed to the higher Risk Category III requirements, although the total assembly occupant load is much lower when compared to a hotel.
To deal with this imbalance, Table 1604.5 includes a new condition under Risk Category III for those buildings containing at least one assembly space with an occupant load greater than 300 while also having a cumulative occupant load for all assembly spaces of more than 2,500. Buildings that meet these criteria are now assigned to Risk Category III rather than Risk Category II.
The new threshold requires the existence of two conditions for the establishment of a Risk Category III classification. First, at least one of the assembly spaces must have an occupant load that exceeds 300, and second, the cumulative occupant load of all assembly spaces must exceed 2,500. In the example shown, both conditions have been met, and the building is to be assigned to Risk Category III.
An additional revision addresses daycare facilities classified as Group I-4 occupancies. These occupancies have not previously been specifically identified in Table 1604.5; however, the threshold at which a Risk Category III is to be assigned to such daycare facilities has now been established. Consistent with the application for when a Group E occupancy is present, a building used for daycare purposes is considered Risk Category III when the total occupant load for the Group I-4 occupancy, or the combination of Group E and Group I-4 occupancies, exceeds 250.
Mixed occupancy buildings with assembly spaces are now designated as Risk Category III when the total public assembly occupant load is greater than 2,500 people.
CHANGE SIGNIFICANCE: Group R-1 hotels often have convention center facilities with multiple large ballrooms and other assembly spaces, but public assembly is not the primary occupancy of the building. These buildings have historically been classified as Risk Category II. Conversely, there are smaller buildings consisting solely of one or more assembly rooms where the primary occupancy is public assembly with a cumulative occupant load of over 300 that must be designed to the higher Risk Category III requirements, although the total assembly occupant load is much lower when compared to a hotel.
To deal with this imbalance, Table 1604.5 includes a new condition under Risk Category III for those buildings containing at least one assembly space with an occupant load greater than 300 while also having a cumulative occupant load for all assembly spaces of more than 2,500. Buildings that meet these criteria are now assigned to Risk Category III rather than Risk Category II.
The new threshold requires the existence of two conditions for the establishment of a Risk Category III classification. First, at least one of the assembly spaces must have an occupant load that exceeds 300, and second, the cumulative occupant load of all assembly spaces must exceed 2,500. In the example shown, both conditions have been met, and the building is to be assigned to Risk Category III.
An additional revision addresses daycare facilities classified as Group I-4 occupancies. These occupancies have not previously been specifically identified in Table 1604.5; however, the threshold at which a Risk Category III is to be assigned to such daycare facilities has now been established. Consistent with the application for when a Group E occupancy is present, a building used for daycare purposes is considered Risk Category III when the total occupant load for the Group I-4 occupancy, or the combination of Group E and Group I-4 occupancies, exceeds 250.