Building Official Determination 24-01: R-4 Relative Hazard Classification
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Source: Building Official Determination 24-01: R-4 Relative Hazard Classification ↗ Last modified: Sun, 19 Apr 2026 20:03:03 GMT
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BOD 24-01: R-4 Relative Hazard Classification
QUESTION: Since Table 24.85-A was developed before R-4 occupancies were added to the building code, which Relative Hazard Classification is appropriate?
RESPONSE: Residential Group R-4 occupancies include buildings with more than five but not more than 16 persons, excluding staff, who reside on a 24-hour basis in a supervised residential environment and receive custodial care.
Due to the number of occupants and nature of occupants, R-4 occupancy is considered more hazardous than R-3 (typically one and two-family residential dwellings) but less hazardous than I-1 occupancy (which includes assisted living facilities with more than 16 occupants). R-4 occupancies are assigned to Relative Hazard Classification 4.
TABLE 24.85-A
Relative Hazard Classification
OSSC Occupancy Classification
Seismic Improvement Standard
6 (Highest)
A, E, I-2, I-3, H-1, H-2, H-3, H-4, H-5
OSSC or ASCE 41-BPON
5
R-1, SR, I-1, I-4
4
R-2, R-4
ASCE 41-BPOE
3
B, M
2
F-1, F-2, S-1, S-2
1 (Lowest)
R-3, U
HISTORY: Implemented January 12, 2024.
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