R 408.10639
R 408.10639 Capacity as affected by population.
Cite as Mich. Admin. Code R 408.10639
Rule 639. (1) The capacity of a means of egress from a building, floor, balcony, tier,
or other occupied space shall be sufficient for the population thereof. The population for
industrial and storage occupancies shall be based on the maximum number of employees
or persons that may be in the space at any time as determined by actual count. All other
types of occupancies shall be not less than the number computed in accordance with the
provisions of table 2.
(2) Mercantile occupancy in a single-story, noncombustible building with an
approved, fully equipped automatic sprinkler system that is in compliance with General
Industry Safety Standard Part 9 “Fixed Fire Equipment,” as referenced in R 408.10606,
may increase the square footage requirement in table 2 by 100%.
(3) The population of an occupancy shall be limited to the existing exit capacity of a
building or space.
(4) Where an exit serves more than 1 floor, only the population of each floor
considered individually need be used in computing the capacity of the exit at that level, if
the exit capacity is not decreased in the direction of exit travel. Where a means of egress
from floors above and below converge at an intermediate level, the capacity of the exit
from the point of convergency shall be not less than the combined capacity of the
converging exits.
(5) Table 2 reads as follows:
TABLE 2
Type of occupancy
Square feet per person
Mercantile, street floor or sales
basement
30
Mercantile, other floors
60
Mercantile, office
100
Mercantile, storage
300
Business
100
Hotel
200
Industrial
100
Note: The computed population of an occupancy is obtained by dividing the total
floor area of a building, floor, or fire area by the indicated square feet per person. Total
floor area means the floor area within the perimeter of the outside walls of a building,
with no deductions for any of the following:
(a) Hallways.
(b) Stairs.
(c) Closets.
(d) Thickness of walls.
(e) Columns.
(f) Other features.
(6) The capacity of an exit route shall be adequate. Information regarding the
"Occupant load" is located in NFPA 101 “Life Safety Code,” 2009 edition and in the
“International Fire Code” 2009 edition, as adopted in R 408.10606.
(7) Exit routes shall support the maximum permitted occupant load for each floor
served.
(8) The capacity of an exit route shall not decrease in the direction of exit route
travel to the exit discharge.