Part 9 of the Ontario Building Code
describes measures for Fire Protection in Section 9.10. There are three distinct terms
to remember when studying Fire Protection:
- Fire Separation
- Fire Resistance Rating
- Fire Protection Rating
Fire separation
A Fire Separation is a construction
assembly that acts as a barrier against the spread of fire and smoke.
Fire resistance ratings (FRR)
Fire Resistance Rating means the time in
hours or fraction thereof that a material or assembly of materials will
withstand the passage of flame and the transmission of heat when exposed to
fire.
Fire-protection rating
Fire Protection Rating means the time in
hours or fraction thereof that a closure will withstand the passage of flame
when exposed to fire.
Determining the required FRR for the floors
and roofs depends on a building’s occupancy and height.
Table 9.10.8.1.
Forming part of sentence 9.10.8.1.(1)
Fire Resistance Ratings for Structural
Members and Assemblies
|
Major Occupancy
|
Maximum
|
Minimum Fire Resistance Rating by Building
Element, min
|
|
|
Building
Height
Storeys
|
Floors Except Floors over Crawl Spaces
|
Mezzanine
Floors
|
Roofs
|
|
Residential(Group C)
|
3
|
45
|
45
|
—
|
|
All other occupancies
|
2
3
|
45
45
|
—
45
|
—
45
|
|
Column 1
|
2
|
3
|
4
|
5
|
When reading Table 9.10.8.1. above,
it is
evident that the separation between floors for Part 9 buildings
will usually be 45 minutes or nothing. The exceptions to this
general rule are listed in a few places such as the following articles - 9.10.8.8.,
9.10.9.11., 9.10.9.14., 9.10.9.16. and 9.10.9.17. The greater the rating of table
9.10.8.1 or these articles shall apply.
Read 9.10.9.11 - As a general rule,
residential occupancies need to be separated from other occupancies with a one
hour rating. If the adjoining occupancy is mercantile (Group E) or medium
hazard industrial (F2), the fire separation will require a fire resistance
rating of 2 hours.
9.10.9.11.(3) states that the separation
need only be 1 hr if there are no more than 2 residential suites contained with
the Group E or F2 occupancy.
Consider the following example: A three
storey building with a hobby store on the ground floor and two residential
apartments above. Using Table 9.10.8.1., a three storey group E building would
require a 45 minute floor. Reading on however to article 9.10.9.11., we
discover that residential occupancies need to be separated from Group E
occupancies with a fire separation having an FRR of 1 hr. The floor between the
hobby shop and the apartment suite above would require a 1 hr. rating.
Figure 1 3 storey building
.