Fire separations, dampers and penetrations (Building Services)

Last updated October 22, 2026

Values this chapter turns on

max closure opening, both compartments sprinklered: 22 m²; max closure opening, both compartments sprinklered
max closure opening if either side is unsprinklered: 11 m²; max closure opening if either side is unsprinklered
damper release rating above max duct temperature: 30°C; damper release rating above max duct temperature
spacing of outlet boxes on opposite wall faces: 600 mm; spacing of outlet boxes on opposite wall faces

Every duct, pipe, cable and outlet box that passes through a rated wall or floor is a hole in a fire separation. Subsections 3.1.8. and 3.1.9. tell you how to keep the separation working: closures in openings, fire dampers and smoke dampers in ducts, firestops around everything else. This is core Building Services material and you should expect several questions, many of them scenarios asking whether a damper is needed or which firestop rating applies.

Fire separations: requirements, continuity and ratings

A wall, partition or floor required to be a fire separation must be continuous and must have the fire-resistance rating the code assigns to it. Openings in it are protected by closures, shafts or other means under Articles 3.1.8.4. to 3.1.8.20. and Subsections 3.1.9. and 3.2.8. OBC Div. B 3.1.8.1..

Continuity OBC Div. B 3.1.8.3.:

A horizontal service space or other concealed space above a vertical fire separation (including shaft walls) must be divided at the separation by an equivalent fire separation.
Where a rated fire separation meets another fire separation, a floor, a ceiling or a roof, the joint gets a firestop with an FT rating at least equal to the abutting separation's fire-resistance rating, tested to CAN/ULC-S115.
The joint between a floor and an exterior wall (the perimeter joint) gets a firestop tested to ASTM E2307 with an F rating at least equal to the floor's rating.
Gypsum board joints at ceilings, floors and wall corners, attached to framing and arranged to restrict flame and smoke, need neither of those firestops.

Closure ratings. A fire-resistance rating applies to an assembly; a fire-protection rating applies to a closure such as a door, window or damper definition. Closure ratings are found by test: CAN/ULC-S104 for doors, S106 for windows and glass block, S112 for fire dampers. The required closure rating depends on the separation rating and is read from the closure table, which generally steps down one level from the wall rating. Smoke dampers and combination dampers have their leakage rated to CAN/ULC-S112.1 (Class I, II or III), and door leakage to ANSI/UL-1784 OBC Div. B 3.1.8.4..

Fire separation	Closure (examples you should be able to find)
1 h	45 min
2 h	1.5 h

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Openings, fire dampers and smoke dampers

Maximum openings in an interior fire separation protected by a closure OBC Div. B 3.1.8.6.:

Condition	Area	Largest dimension
Either fire compartment unsprinklered	11 m²	3.7 m
Both fire compartments sprinklered	22 m²	6 m

Where dampers go. A fire damper is required in every duct or air-transfer opening through an assembly required to be a fire separation, unless waived OBC Div. B 3.1.8.7.. A smoke damper or combination smoke/fire damper is also required where the separation:

separates a public corridor,
contains a particular egress door referred to in 3.4.2.4.(2),
serves an assembly, care, care and treatment, detention or residential occupancy, or
is installed to meet 3.3.1.7.(1)(b), 3.3.3.5.(4) or 3.3.4.11.(4).

Fire damper waivers OBC Div. B 3.1.8.8.:

Case	Condition
Commercial cooking exhaust ducts	Always waived (a damper would trap grease)
Separation not required to have a rating	Any duct in a vertical one; noncombustible ducts in a horizontal one
Continuous noncombustible duct, melting point above 760°C	Through a vertical suite separation in A, E or F occupancies
Small branch duct, noncombustible, above 760°C	0.013 m² or less serving room AC units discharging 1.2 m or less above the floor
Branch into exhaust riser	Extends at least 500 mm into an upward-flow riser under negative pressure
Duct in a vertical service space	Each duct exhausts directly outdoors at the top
Elementary or secondary school	Continuous noncombustible duct through a 30 min separation
Small B3 home (10 or fewer sleeping, 6 or fewer needing help, fire alarm)	Duct-type smoke detectors control smoke instead

Installing a fire damper OBC Div. B 3.1.8.10.: in the plane of the separation so it stays put if the duct falls; closed automatically by a ULC-S505 fusible link or other heat- or smoke-actuated device; any heat-actuated device placed where duct temperature rise reaches it and rated about 30°C above the highest system temperature (running or off); installed in the orientation it was tested in; and with a tight access door for inspection and resetting.

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Hold-open devices and sprinkler-protected glazing

Hold-open devices are allowed on closures in required fire separations, but never on an exit stair door in a building over 3 storeys or on a vestibule door required by 3.3.5.7. OBC Div. B 3.1.8.14..

Building condition	Release signal
Single-stage fire alarm	Any fire alarm signal
2-stage fire alarm	Any alert signal, or adjacent smoke detectors
Fire alarm, sensitive doors (exit doors, public corridor doors, residential and care closures, smoke control doors)	A smoke detector on the fire alarm system located per CAN/ULC-S524
No fire alarm, sensitive doors	A smoke alarm on either side at ceiling level within 1.5 m of the opening
Other closures	A heat-actuated device is enough

A door between a public corridor and a sleeping room in a care and treatment occupancy need not release automatically on the fire alarm.

Sprinkler-protected glazed wall assemblies are built to CAN/ULC-S136 OBC Div. B 3.1.8.20.. They are not allowed in separations over 2 h, in firewalls, in high-hazard industrial occupancies, or in exits serving high-building floor areas or care, care and treatment, detention or residential occupancies. Where used in an exit separation, the building must be sprinklered throughout and no more than half the required exits from a floor area may rely on them.

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Penetrations in fire separations

The base rule: a penetration of a fire separation, or of a membrane of a rated assembly, is sealed by a firestop with an F rating not less than the separation's required rating, or is cast in place where the penetrating item is steel, ferrous, copper, concrete or masonry OBC Div. B 3.1.9.1.. Firewalls and the horizontal separations under 3.2.1.2. need the stricter FT rating. Sprinklers need only a metal escutcheon per NFPA 13, and fire dampers installed per NFPA 80 need no separate firestop.

Item	Key rule
Ducts, pipes, cables, raceways	Firestop per 3.1.9.1.(1) OBC Div. B 3.1.9.2.
Combustible raceway in a slab	At least 50 mm of concrete below it
Noncombustible outlet box	No firestop if 0.016 m² or less, 0.065 m² total per 9.3 m², annular gap 3 mm or less OBC Div. B 3.1.9.3.
Boxes on opposite sides of a rated wall	600 mm apart, or fire block, or FT-rated firestop on each
Combustible sprinkler pipe	Both sides sprinklered OBC Div. B 3.1.9.4.
Combustible DWV pipe	F-rated firestop (tested at 50 Pa if over 3 storeys), not in a vertical service space
Chlorine gas pipe at a pool	25 mm or less, firestopped
Openings into ducts through a membrane ceiling	Sheet steel ducts; fire stop flaps to CAN/ULC-S112.2 OBC Div. B 3.1.9.5.

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Common traps

F rating vs FT rating: firewalls and 3.2.1.2. horizontal separations need FT.
A fire damper in a horizontal separation must have been tested horizontally.
The 30°C margin is above the system maximum, not room temperature.
Smoke dampers are a separate trigger list from fire dampers.
Hold-open devices are never allowed on exit stair doors in buildings over 3 storeys.

Chapter review

Chapter at a glance

One line per section: the idea to carry into the exam. Then the answers that most often catch candidates out.

Chapter at a glance: the key idea in each section
Section	Key idea
Fire separations: requirements, continuity and ratings	A wall, partition or floor required to be a fire separation must be continuous and must have the fire-resistance rating the code assigns to it.
Openings, fire dampers and smoke dampers	Installing a fire damper: in the plane of the separation so it stays put if the duct falls; closed automatically by a ULC-S505 fusible link or other heat- or smoke-actuated…
Hold-open devices and sprinkler-protected glazing	Hold-open devices are allowed on closures in required fire separations, but never on an exit stair door in a building over 3 storeys or on a vestibule door required by 3.3.5.7..
Penetrations in fire separations	The base rule: a penetration of a fire separation, or of a membrane of a rated assembly, is sealed by a firestop with an F rating not less than the separation's required rating…

Fire separations: requirements, continuity and ratings
A wall, partition or floor required to be a fire separation must be continuous and must have the fire-resistance rating the code assigns to it.
Openings, fire dampers and smoke dampers
Installing a fire damper: in the plane of the separation so it stays put if the duct falls; closed automatically by a ULC-S505 fusible link or other heat- or smoke-actuated…
Hold-open devices and sprinkler-protected glazing
Hold-open devices are allowed on closures in required fire separations, but never on an exit stair door in a building over 3 storeys or on a vestibule door required by 3.3.5.7..
Penetrations in fire separations
The base rule: a penetration of a fire separation, or of a membrane of a rated assembly, is sealed by a firestop with an F rating not less than the separation's required rating…

Usual exam traps

F rating vs FT rating: firewalls and 3.2.1.2. horizontal separations need FT.
A fire damper in a horizontal separation must have been tested horizontally.
The 30°C margin is above the system maximum, not room temperature.
Smoke dampers are a separate trigger list from fire dampers.
Hold-open devices are never allowed on exit stair doors in buildings over 3 storeys.

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Questions on Fire separations, dampers and penetrations (3.1.8, 3.1.9), in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.

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Code cited in this chapter

Based on the official 2024 Building Code Compendium on ontario.ca.

OBC Div. B 3.1.8.1. General Requirements
(1)Any wall, partition or floor assembly required to be a fire separation shall
(a)except as permitted by Sentence (2), be constructed as a continuous element in conformance with Article 3.1.8.3., and
(b)as required in this Part, have a fire-resistance rating as specified. (See Note A-3.1.8.1.(1)(b))
(2)Openings in a fire separation shall be protected with closures, shafts or other means in conformance with Articles 3.1.8.4. to 3.1.8.20. and Subsections 3.1.9. and 3.2.8. (See Note A-3.1.8.1.(2))
Open OBC Div. B 3.1.8.1. in the code viewer
OBC Div. B 3.1.8.3. Continuity of Fire Separations
(1)Except as permitted by Sentence 3.6.4.2.(2), a horizontal service space or other concealed space located above a required vertical fire separation, including the walls of a vertical shaft, shall be divided at the fire separation by an equivalent fire separation within the service space.
(2)Except as provided in Sentence (5), the continuity of a fire separation having a fire-resistance rating that abuts another fire separation, a floor, a ceiling, or a roof shall be maintained by a firestop conforming to Sentence (3). (See Note A-3.1.8.3.(2))
(3)The firestop required in Sentence (2) shall have an FT rating not less than the fire-resistance rating of the abutting fire separation when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems."
(4)Except as provided in Sentence (5), joints located in a horizontal plane between a floor and an exterior wall shall be sealed by a firestop that, when subjected to the fire test method in ASTM E2307, "Standard Test Method for Determining Fire Resistance of Perimeter Fire Barriers Using Intermediate-Scale, Multi-storey Test Apparatus," has an F rating not less than the fire-resistance rating of the horizontal fire separation.
(5)Joints between ceilings and walls, between floors and walls, and between walls at corners need not comply with Sentences (2) and (4) where such joints consist of gypsum board that is attached to framing members and arranged so as to restrict the passage of flame and smoke through the joints. (See Note A-3.1.8.3.(5))
Open OBC Div. B 3.1.8.3. in the code viewer
OBC Div. A 1.4.1.2.(1) Fire-protection rating
Fire-protection rating means the time in minutes or hours that a closure will withstand the passage of flame when exposed to fire under specified conditions of test and performance criteria, or as otherwise prescribed in this Code.
Open OBC Div. A 1.4.1.2.(1) in the code viewer
OBC Div. B 3.1.8.4. Determination of Ratings and Classifications
(1)Except as permitted by Sentences (2) and 3.1.8.16.(1), the fire-protection rating of a closure shall be determined in accordance with
(a)CAN/ULC-S104, "Standard Method for Fire Tests of Door Assemblies,"
(b)CAN/ULC-S106, "Standard Method for Fire Tests of Window and Glass Block Assemblies," or
(c)CAN/ULC-S112, "Standard Method for Fire Test of Fire Damper Assemblies." (See Articles 3.1.8.17. to 3.1.8.19. for additional requirements for closures.)
(2)Except as permitted by Sentence 3.1.8.12.(1), the fire-protection rating of a closure shall conform to Table 3.1.8.4. for the required fire-resistance rating of the fire separation.
(3)The leakage rate of smoke dampers and combination smoke/ fire dampers shall
(a)be determined in accordance with the applicable provisions in CAN/ULC-S112.1, "Standard for Leakage Rated Dampers for Use in Smoke Control Systems," and
(b)conform to Class I, II or III of that standard.
(4)The leakage rate of a door assembly shall be determined in accordance with ANSI/UL-1784, "Standard for Air Leakage Tests of Door Assemblies and Other Opening Protectives."
Open OBC Div. B 3.1.8.4. in the code viewer
OBC Div. B 3.1.8.6. Maximum Openings
(1)The size of an opening in an interior fire separation required to be protected with a closure shall be not more than 11 m², with no dimension more than 3.7 m, if a fire compartment on either side of the fire separation is not sprinklered.
(2)The size of an opening in an interior fire separation required to be protected with a closure shall be not more than 22 m², with no dimension more than 6 m, provided the fire compartments on both sides of the fire separation are sprinklered.
Open OBC Div. B 3.1.8.6. in the code viewer
OBC Div. B 3.1.8.7. Location of Fire Dampers and Smoke Dampers
(1)Except as provided in Article 3.1.8.8., a fire damper having a fire-protection rating conforming to Sentence 3.1.8.4.(2) shall be installed in conformance with Article 3.1.8.10. in ducts or air-transfer openings that penetrate an assembly required to be a fire separation.
(2)Except as provided in Article 3.1.8.9., a smoke damper or a combination smoke/fire damper shall be installed in conformance with Article 3.1.8.11. in ducts or air-transfer openings that penetrate an assembly required to be a fire separation, where the fire separation
(a)separates a public corridor,
(b)contains an egress door referred to in Sentence 3.4.2.4.(2),
(c)serves an assembly, care, care and treatment, detention or residential occupancy, or
(d)is installed to meet the requirements of Clause 3.3.1.7.(1)(b) or Sentence 3.3.3.5.(4). or 3.3.4.11.(4).
Open OBC Div. B 3.1.8.7. in the code viewer
OBC Div. B 3.1.8.8. Fire Dampers Waived
(1)Except as provided in Sentences (2) to (4), the requirement for fire dampers stated in Sentence 3.1.8.7.(1) is permitted to be waived for
(a)ducts that serve commercial cooking equipment, (See also Article 6.3.1.6.)
(b)continuous noncombustible ducts having a melting point above 760°C that penetrate a vertical fire separation required by Sentence 3.3.1.1.(1) between suites of assembly, mercantile, low-hazard industrial, medium-hazard industrial or high-hazard industrial occupancy,
(c)ducts or air-transfer openings that penetrate a vertical fire separation not required to have a fire-resistance rating, or
(d)noncombustible ducts or air-transfer openings that penetrate a horizontal fire separation not required to have a fire-resistance rating.
(2)The requirement for fire dampers stated in Sentence 3.1.8.7.(1) is permitted to be waived for noncombustible branch ducts having a melting point above 760°C that penetrate a fire separation,
(a)provided the ducts
(i)have a cross-sectional area not more than 0.013 m² and serve only air-conditioning units or combined air-conditioning and heating units discharging air not more than 1.2 m above the floor, or
(ii)extend not less than 500 mm inside exhaust duct risers that are under negative pressure and in which the airflow is upward as required by Article 3.6.3.4., or
(b)where the fire separation separates a vertical service space from the remainder of the building, provided each individual duct exhausts directly to the outdoors at the top of the vertical service space.
(3)In elementary and secondary schools, a continuous noncombustible duct having a melting point above 760°C that pierces a fire separation having a fire-resistance rating of 30 min need not be equipped with a fire damper at the fire separation.
(4)In a Group B, Division 3 occupancy which contains sleeping accommodation for not more than 10 persons, which has not more than six occupants who require assistance in evacuation in case of an emergency and which is equipped with a fire alarm system, a duct need not be equipped with a fire damper at a fire separation, provided duct-type smoke detectors have been installed to control smoke circulation as described in Article 3.2.4.12.
Open OBC Div. B 3.1.8.8. in the code viewer
OBC Div. B 3.1.8.10. Installation of Fire Dampers
(1)A fire damper shall be installed in the plane of the fire separation so as to stay in place should the duct become dislodged during a fire. (See Note A-3.1.8.10.(1))
(2)A fire damper shall be arranged so as to close automatically upon the operation of a fusible link conforming to ULC-S505, "Standard for Fusible Links for Fire Protection Services," or other heat-actuated or smoke-actuated device.
(3)A heat-actuated device referred to in Sentence (2) shall
(a)be located where it is readily affected by an abnormal rise of temperature in the duct, and
(b)have a temperature rating approximately 30°C above the maximum temperature that would exist in the system either with the system in operation or shut down.
(4)A fire damper tested in the vertical or horizontal position shall be installed in the position in which it was tested.
(5)A tightly fitted access door shall be installed for each fire damper to provide access for the inspection of the damper and the resetting of the release device. (See Note A-3.1.8.10.(5))
Open OBC Div. B 3.1.8.10. in the code viewer

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OBC Div. B 3.1.8.14. Hold-Open Devices
(1)Except as provided in Sentences 3.1.8.10.(2) and 3.1.8.11.(3), a hold-open device is permitted to be used on a closure in a required fire separation, other than on an exit stair door in a building more than 3 storeys in building height and on a door for a vestibule required by Article 3.3.5.7., provided the device is designed to release the closure in conformance with this Article.
(2)Except as provided in Sentences (5) and (6), where the building is provided with a fire alarm system, a hold-open device permitted by Sentence (1) shall release
(a)in a single-stage system, upon any signal from the fire alarm system, and
(b)in a 2-stage system,
(i)upon any alert signal from the fire alarm system, or
(ii)upon actuation of any adjacent smoke detectors.
(3)Where the building is provided with a fire alarm system, a hold-open device permitted by Sentence (1) shall release upon a signal from a smoke detector connected to the fire alarm system and located as described in CAN/ULC-S524, "Standard for Installation of Fire Alarm Systems," where the hold-open device is used on
(a)an exit door,
(b)a door opening into a public corridor,
(c)an egress door referred to in Sentence 3.4.2.4.(2),
(d)a closure serving an assembly, care, care and treatment, detention, or residential occupancy,
(e)a door in a fire separation referred to in Clause 3.3.1.7.(1)(b) or Sentence 3.3.3.5.(4) or 3.3.4.11.(4), or
(f)a door required to function as part of a smoke control system.
(4)Where the building is not provided with a fire alarm system, a hold-open device permitted by Sentence (1) shall release upon a signal from a smoke alarm located on either side of the fire separation at ceiling level within 1.5 m horizontally of the closure opening in the fire separation, where the hold-open device is used on closures described in Clauses (3)(a) to (e).
(5)Where a hold-open device is used on closures other than those described in Sentences (3) and (4), it is permitted to be released upon actuation of a heat-actuated device.
(6)A hold-open device used on a door located between a corridor used by the public and an adjacent sleeping room in a care and treatment occupancy need not release automatically as stated in Sentence (2).
Open OBC Div. B 3.1.8.14. in the code viewer
OBC Div. B 3.1.8.20. Sprinkler Protected Glazed Wall Assembly
(1)A sprinkler protected glazed wall assembly shall be constructed in accordance with the requirements of CAN/ULC-S136, "Standard Method of Fire Test of Sprinkler Protected Window Systems."
(2)A sprinkler protected glazed wall assembly shall not be installed in
(a)fire separations requiring a fire-resistance rating of more than 2 h,
(b)a firewall,
(c)a high-hazard industrial occupancy, or
(d)any part of an exit serving
(i)a floor area subject to the requirements of Subsection 3.2.6.,
(ii)a care occupancy,
(iii)a care and treatment occupancy,
(iv)a detention occupancy, or
(v)a residential occupancy.
(3)Where a sprinkler protected glazed wall assembly is installed in an exit fire separation permitted in Sentence (2),
(a)the building shall be sprinklered throughout, and
(b)the exits protected with the sprinkler protected glazed wall assemblies shall not comprise more than one-half of the required number of exits from any floor area.
Open OBC Div. B 3.1.8.20. in the code viewer
OBC Div. B 3.1.9.1. Firestops
(1)Except as provided in Sentences (2) to (7) and Article 3.1.9.3., penetrations of a fire separation or a membrane forming part of an assembly required to have a fire-resistance rating shall be
(a)sealed by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an F rating not less than the required fire-resistance rating of the fire separation, or
(b)cast-in-place, where the item penetrating the fire separation is steel, ferrous, copper, concrete or masonry. (See Note A-3.1.9.1.(1)(b))
(See also Article 3.1.9.4. for requirements regarding penetrations by combustible drain, waste and vent piping.)
(2)Except as permitted in Sentence (6), penetrations of a firewall or a horizontal fire separation that is required to have a fire-resistance rating in conformance with Article 3.2.1.2. shall be sealed at the penetration by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an FT rating not less than the fire-resistance rating for the fire separation.
(3)Except as permitted in Sentences (6) and (7), penetrations of a fire separation in conformance with Sentence 3.6.4.2.(2) shall be sealed by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an FT rating not less than the fire-resistance rating for the fire separation of the assembly.
(4)Sprinklers are permitted to penetrate a fire separation or a membrane forming part of an assembly required to have a fire-resistance rating without having to meet the firestop requirements of Sentences (1) to (3), provided the annular space created by the penetration of a fire sprinkler is covered by a metal escutcheon plate in accordance with NFPA 13, "Standard for the Installation of Sprinkler Systems."
(5)Unless specifically designed with a firestop, fire dampers are permitted to penetrate a fire separation or a membrane forming part of an assembly required to have a fire-resistance rating without having to meet the firestop requirements of Sentences (1) to (3), provided the fire damper is installed in conformance with NFPA 80, "Standard for Fire Doors and Other Opening Protectives."
(6)Service equipment penetrations through a horizontal fire separation having a fire-resistance rating as described in Sentences (2) and (3) that are contained within the cavity of a wall above and below the horizontal fire separation are permitted to be sealed at the penetration by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an F rating not less than the fire-resistance rating for the fire separation.
(7)Service equipment penetrations through a horizontal fire separation having a fire-resistance rating as described in Sentence (3) are permitted to be sealed at the penetration by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an F rating not less than the fire-resistance rating for the fire separation, provided the penetration
(a)is contained within the concealed space of a floor or ceiling assembly having a fire-resistance rating,
(b)is located above a ceiling membrane that is a horizontal fire separation, or
(c)is contained within a horizontal service space conforming to Subsection 3.6.4. that is directly above or below the floor.
Open OBC Div. B 3.1.9.1. in the code viewer
OBC Div. B 3.1.9.2. Service Equipment Penetrations
(1)Ducts, electrical outlet boxes, pipes, totally enclosed raceways, optical fibre cables, electrical wires and cables, and other similar service equipment are permitted to penetrate a fire separation or a membrane forming part of an assembly required to have a fire-resistance rating, provided they are protected at the penetration with a firestop conforming to Sentence 3.1.9.1.(1). (See Note A-3.1.9.2.(1))
(2)Combustible totally enclosed raceways that are embedded in a concrete floor slab are permitted in an assembly required to have a fire-resistance rating, provided the concrete cover between the raceway and the bottom of the slab is not less than 50 mm.
Open OBC Div. B 3.1.9.2. in the code viewer
OBC Div. B 3.1.9.3. Penetration by Outlet Boxes (See also Note A-3.1.9.2.(1))
(1)Except as provided in Sentence (3), outlet boxes are permitted to penetrate the membrane of an assembly required to have a fire-resistance rating, provided they are sealed at the penetration by a firestop that has an FT rating not less than the fire-resistance rating of the fire separation when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems."
(2)Combustible outlet boxes are permitted to penetrate the membrane of an assembly required to have a fire-resistance rating, provided they are sealed at the penetration by a firestop that, when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," has an FT rating not less than the fire-resistance rating for the fire separation.
(3)Except as provided in Sentences 3.1.9.1.(2) and (3), noncombustible outlet boxes that penetrate a vertical fire separation or a membrane forming part of an assembly required to have a fire-resistance rating need not conform to Sentence (1), provided
(a)they do not exceed,
(i)0.016 m² in area, and
(ii)an aggregate area of 0.065 m² in any 9.3 m² of surface area, and
(b)the annular space between the membrane and noncombustible electrical outlet boxes does not exceed 3 mm.
(4)Outlet boxes on opposite sides of a vertical fire separation having a fire-resistance rating shall be separated by
(a)a horizontal distance of not less than 600 mm,
(b)a fire block conforming to Article 3.1.11.7., or
(c)a firestop installed on each outlet box that has an FT rating not less than the fire-resistance rating of the fire separation when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems."
Open OBC Div. B 3.1.9.3. in the code viewer
OBC Div. B 3.1.9.4. Combustible Piping Penetrations
(1)Combustible sprinkler piping is permitted to penetrate a fire separation provided the fire compartments on each side of the fire separation are sprinklered.
(2)Combustible water distribution piping is permitted to penetrate a fire separation that is required to have a fire-resistance rating, provided the piping is protected at the penetration with a firestop in conformance with Clause (4)(a) or (b).
(3)Except as permitted by Sentences (4), (5), (7) and (8), combustible piping shall not be used in a drain, waste and vent piping system if any part of that system penetrates
(a)a fire separation required to have a fire-resistance rating, or
(b)a membrane that forms part of an assembly required to have a fire-resistance rating.
(4)Combustible drain, waste and vent piping is permitted to penetrate a fire separation required to have a fire-resistance rating or a membrane that forms part of an assembly required to have a fire-resistance rating, provided
(a)except as provided in Clause (b), the piping is sealed at the penetration by a firestop that has an F rating not less than the fire-resistance rating required for the fire separation when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems,"
(b)in buildings more than 3 storeys in building height, the piping is sealed at the penetration by a firestop that has an F rating not less than the fire-resistance rating required for the fire separation when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," with a pressure differential of 50 Pa between the exposed and unexposed sides, with the higher pressure on the exposed side, and
(c)the piping is not located in a vertical service space.
(5)Combustible drain, waste and vent piping is permitted on one side of a vertical fire separation provided it is not located in a vertical service space.
(6)Combustible piping for central vacuum systems is permitted to penetrate a fire separation, provided the installation conforms to the requirements that apply to combustible drain, waste and vent piping specified in Sentence (4).
(7)Except as provided in Sentence (8), penetrations of a fire separation that incorporate transitions between combustible and noncombustible drain, waste and vent piping shall be sealed by a firestop that has an F rating not less than the fire-resistance rating required for the fire separation when subjected to the fire test method in CAN/ULC-S115, "Standard Method of Fire Tests of Firestop Systems," with a pressure differential of 50 Pa between the exposed and unexposed sides, with the higher pressure on the exposed side.
(8)Transitions between vertical noncombustible drain, waste and vent piping and combustible branches for drain, waste and vent piping are permitted on either side of a fire separation, provided they are not located in a vertical service space. (See Note A-3.1.9.4.(8))
(9)Combustible piping not more than 25 mm in diameter containing chlorine gas is permitted to penetrate a fire separation between a chlorine gas service room built in conjunction with a public pool or public spa and the remainder of the building, provided the piping is sealed at the penetration by a firestop in conformance with Clause 3.1.9.1.(1)(a).
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OBC Div. B 3.1.9.5. Openings Through a Membrane Ceiling
(1)A membrane ceiling forming part of an assembly assigned a fire-resistance rating on the basis of MMAH Supplementary Standard SB-2, "Fire Performance Ratings," is permitted to be penetrated by openings leading into ducts within the ceiling space provided
(a)the ducts are sheet steel, and
(b)the number of openings and their protection conform to the requirements of MMAH Supplementary Standard SB-2, "Fire Performance Ratings."
(2)Fire stop flaps in ceiling membranes required in Sentence (1) shall conform to CAN/ULC-S112.2, "Standard Method of Fire Test of Ceiling Firestop Flap Assemblies."
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