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Question: Does Table 3.1.16.1 limit a designer's ability to determine occupant load?
The Code defines occupant load as the number of persons for which a building or part of a building is designed. Occupant loads are used to assess the number and width of exit facilities, the width of access routes leading to exits, the number of sanitary fixtures, whether a fire alarm system must be installed, and certain additional requirements for high buildings.
An occupant load is determined on the basis of the total number of persons that a building, or space, is expected to accommodate. In most cases, the owner/tenant and design team determine the expected number of occupants based on the nature of the occupancy and use. Where the occupant load is unknown or uncertain, designers can turn to Table 3.1.16.1. for guidance on occupant loads for typical uses. Specifically, Clause 3.1.16.1.(1)(c) allows designers to choose the occupant load based on the number of persons for which the area is designed or on the occupant load concentration found in Table 3.1.16.1.
Table 3.1.16.1. is not intended to be an upper or lower limit on occupant
load design. For example, even though the table lists 9.3 m² per person
for offices, it is permissible to have offices that provide less space
per person. In this case, the occupant load of the offices would be higher
than that normally anticipated
and the higher value would be used for Code design purposes. Similarly,
one might design a classroom to provide more space for students than the
1.85 m² per person value in Table 3.1.16.1. The design occupant load
of the classroom would be lower than that normally anticipated by the Table.
There are three important exceptions to this approach. Where the space
is used as an assembly occupancy with fixed seats, Clause 3.1.16.1.(1)(a)
requires the occupant load to be based on the
actual number of fixed
seats. Similarly, Clause 3.1.16.1.(1)(b) requires the occupant load for
dwelling units and suites to be based on 2 persons in each sleeping room
or sleeping area. Finally, the Code sets an upper limit on the occupant
load (lower limit on the area per person) in restaurants where alcohol
is served and drinking establishments. The seating and standup areas of
bars and restaurants are limited to ensure occupants can easily evacuate
in an emergency. Sentence 3.1.16.1.(5) limits the design occupant load
of these areas to 0.6 m² per person.
A notice must be posted where the design occupant load varies from that
found in the table. The sign is to include the actual design occupant load
and be located in a conspicuous location. Posting helps ensure that the
building will not become crowded beyond its capacity. Similarly, it provides
a signal to the building occupants, future users, and fire and building
officials that the space has been safely designed to accommodate a specific
number of occupants in terms of the aforementioned exit, egress, plumbing
fixture, early warning and high building requirements.
It is prudent for designers to consider future use of the building and
to make allowance for reasonably foreseeable changes in occupant load.
Other legislation may also govern the maximum number of persons permitted
in certain occupancies, and may at times be considered applicable law.
This opinion is provided by the Housing Development and Buildings Branch
of the Ministry of Municipal Affairs and Housing. Under the Building Code
Act, the local municipality is the authority having jurisdiction for enforcing
the Ontario Building Code Act and its Regulations.
Article 3.1.16.1. - Occupant
Load
(1)
(1) The occupant
load of a floor
area or part of afloor
area, or of a building
or part of abuilding
not having a floor
area, shall be based on
(a)
the number of seats in an assembly
occupancy having fixed seats,
(b)
2 persons per sleeping room or sleeping area in a dwelling
unit or suite,
or
(c)
the number of persons
(i)
for which the area is designed, or
(ii)
determined from Table 3.1.16.1. foroccupancies
other than those described in Clauses (a) and (b).
(2)
If a floor
area or part thereof has been designed for an occupant
load other than that determined from Table 3.1.16.1., a permanent sign
indicating that occupant
load shall be posted in a conspicuous location.
(3)
For the purposes of this Article, mezzanines,
tiers and balconies shall be regarded as part of the floor
area.
(4)
If a room or group of rooms is intended for different occupancies
at different times, the value to be used from Table 3.1.16.1. shall
be the value which gives the greatest number of persons for the occupancies
concerned.
(5)
Except as provided by Sentences (6) or (7), in dining, alcoholic beverage
and cafeteria spaces the occupant
load shall be determined from Table 3.1.16.1.
(6)
The occupant
load in Sentence (5) is permitted to be the number of persons for which
the space is designed.
(7)
The occupant
load in Sentence (6) shall be not more than that determined by using
an area of 0.6 m² per person.
Ali Arlani
October 25, 1999
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