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Values this chapter turns on
- fire damper release rating above system max temp
- 30°C
- fire damper release rating above system max temp
- max flame-spread for unprotected combustible insulation
- 25
- max flame-spread for unprotected combustible insulation
- concrete cover under embedded combustible raceways
- 50 mm
- concrete cover under embedded combustible raceways
- fewer than this may run off domestic water
- 9 sprinklers
- fewer than this may run off domestic water
The HVAC - House syllabus pulls five Articles out of Part 3. They matter because Part 9 points to them: a Part 9 fire damper must meet Articles 3.1.8.4. and 3.1.8.10., and a Part 9 sprinkler system is designed under Article 3.2.5.12. Expect a few direct lookup questions here, usually on fire damper installation and on which NFPA sprinkler standard may be used.
Combustible insulation and ratings
Combustible insulation. Article 3.1.5.14. governs combustible insulation in buildings that are required to be of noncombustible construction OBC Div. B 3.1.5.14.OBC Div. B 3.1.5.14. Combustible Insulation)(1) Foamed plastic insulation shall conform to Article 3.1.5.15. (1) Combustible insulation with a flame-spread rating not more than 25 on any exposed surface, or any surface that would be exposed by cutting through the material in any direction, is permitted in a building required to be of noncombustible…. The key thresholds are flame-spread ratings:
| Insulation flame-spread rating | Where permitted in a noncombustible building |
|---|---|
| Not more than 25 | Permitted generally |
| More than 25, not more than 500 | Permitted if protected from the adjacent space by a thermal barrier (for example 12.7 mm gypsum board fastened independently of the insulation, lath and plaster, masonry or concrete) |
| Any | Above roof decks, outside foundation walls below ground, and beneath slabs-on-ground |
For unsprinklered noncombustible buildings more than 18 m high, the thermal barrier rules get stricter (thicker Type X gypsum board in interior walls, ceilings and roofs). HVAC designers meet this Article through Part 9 references, for example Sentence 9.33.6.4.(7), which lets foamed plastic insulation sit in a ceiling space used as a return air plenum only if protected in accordance with Sentence 3.1.5.14.(4).
Ratings of closures. A closure's fire-protection rating is determined by test to CAN/ULC-S104 (doors), CAN/ULC-S106 (windows and glass block) or CAN/ULC-S112 (fire damper assemblies) OBC Div. B 3.1.8.4.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…. The required rating of the closure depends on the fire-resistance rating of the fire separation, read from the closure table. Smoke dampers and combination smoke/fire dampers have their leakage rate determined under CAN/ULC-S112.1 and must meet Class I, II or III.
Remember the two different words. A fire-resistance rating belongs to an assembly (wall, floor). A fire-protection rating belongs to a closure (door, damper, window) definitionOBC Div. A 1.4.1.2.(1) Fire-protection ratingFire-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..
Fire dampers and service penetrations
Installing a fire damper OBC Div. B 3.1.8.10.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…:
| Requirement | Detail |
|---|---|
| Position | In the plane of the fire separation, so it stays in place if the duct falls away in a fire |
| Release | Closes automatically when a fusible link (ULC-S505) or other heat- or smoke-actuated device operates |
| Heat-actuated device location | Where an abnormal temperature rise in the duct will readily affect it |
| Heat-actuated device rating | About 30°C above the maximum temperature in the system, running or shut down |
| Orientation | Installed in the position (vertical or horizontal) in which it was tested |
| Access | A tightly fitted access door for each damper, for inspection and resetting |
Service equipment penetrations. Ducts, outlet boxes, pipes, totally enclosed raceways, optical fibre and electrical cables may penetrate a fire separation, or a membrane of a rated assembly, if a firestop protects the penetration OBC Div. B 3.1.9.2.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…. Combustible totally enclosed raceways embedded in a concrete slab are allowed in a rated assembly if there is at least 50 mm of concrete cover below the raceway. Part 9 repeats the same 50 mm rule in Sentence 9.10.9.9.(1).
Automatic sprinkler systems
The default sprinkler standard is NFPA 13 OBC Div. B 3.2.5.12.OBC Div. B 3.2.5.12. Automatic Sprinkler Systems(1) Except as provided by Sentences (2) to (4) and (9), an automatic sprinkler system shall be designed, constructed, installed and tested in conformance with NFPA 13, "Standard for the Installation of Sprinkler Systems." (See Note A-3.2.5.12.(1)) (2) Instead of the requirements of Sentence (1), NFPA 13R, "Standard…. The code allows lighter standards in defined cases:
| Standard | Permitted for (summary) |
|---|---|
| NFPA 13 | All buildings (default) |
| NFPA 13R | Residential buildings not more than 4 storeys meeting listed construction Articles; small Group B, Division 3 buildings; certain retirement homes |
| NFPA 13D | Residential buildings with not more than two dwelling units; some larger residential buildings where no dwelling unit is above another (except a secondary suite) and listed conditions are met |
Other numbers to note in the same Article:
- A building with fewer than 9 sprinklers may take its sprinkler water from the domestic water system, if the domestic system can meet the required flow.
- Where one water supply serves sprinklers and other equipment, control valves must let either system be shut off on its own.
- Sprinklers cannot be omitted in any room or closet on the storey directly below a roof assembly, whatever the standard says.
- An NFPA 13D system in a retirement home needs at least a 20 min water supply.
Why this matters on an HVAC exam: Part 9 sends sprinkler design to Articles 3.2.5.12. to 3.2.5.15. and 3.2.5.17. (Sentence 9.10.1.3.(8)), and sprinkler piping may pass through a fire separation only where both sides are sprinklered (Sentence 9.10.9.9.(3)).
Common traps
- Confusing the 30°C margin for a fire damper's heat-actuated device with a fixed temperature. The code sets the margin above the system's own maximum temperature.
- Installing a horizontally tested damper in a vertical position. Not permitted.
- Thinking a fire damper may sit anywhere along the duct. It must be in the plane of the fire separation.
- Assuming 13D is available for any residential building. Check the dwelling unit count and the stacking conditions.
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.
- Combustible insulation and ratings
For unsprinklered noncombustible buildings more than 18 m high, the thermal barrier rules get stricter (thicker Type X gypsum board in interior walls, ceilings and roofs).
- Fire dampers and service penetrations
A supply duct normally carries air at up to 45°C during heating.
- Automatic sprinkler systems
Why this matters on an HVAC exam: Part 9 sends sprinkler design to Articles 3.2.5.12. to 3.2.5.15. and 3.2.5.17. (Sentence 9.10.1.3.(8)), and sprinkler piping may pass through a…
Usual exam traps
- Confusing the 30°C margin for a fire damper's heat-actuated device with a fixed temperature. The code sets the margin above the system's own maximum temperature.
- Installing a horizontally tested damper in a vertical position. Not permitted.
- Thinking a fire damper may sit anywhere along the duct. It must be in the plane of the fire separation.
- Assuming 13D is available for any residential building. Check the dwelling unit count and the stacking conditions.
Practice this chapter
Questions on Part 3 fire safety items for HVAC, in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.
Code cited in this chapter
Based on the official 2024 Building Code Compendium on ontario.ca.
© King's Printer for Ontario, 2024. Reproduced with permission.
OBC Div. B 3.1.5.14. Combustible Insulation)
Open OBC Div. B 3.1.5.14. in the code viewer(1)Foamed plastic insulation shall conform to Article 3.1.5.15.
(1) Combustible insulation with a flame-spread rating not more than 25 on any exposed surface, or any surface that would be exposed by cutting through the material in any direction, is permitted in a building required to be of noncombustible construction.
(2)Combustible insulation is permitted to be installed above roof decks, outside of foundation walls below ground level and beneath concrete slabs-on-ground of buildings required to be of noncombustible construction.
(3)Except as provided in Sentences (5) and (6), combustible insulation with a flame-spread rating more than 25 but not more than 500 on any exposed surface, or any surface that would be exposed by cutting through the material in any direction, is permitted in a building required to be of noncombustible construction, provided the insulation is protected from adjacent space in the building, other than adjacent concealed spaces within wall assemblies, by a thermal barrier consisting of
(a)not less than 12.7 mm thick gypsum board mechanically fastened to a supporting assembly independent of the insulation.
(b)lath and plaster, mechanically fastened to a supporting assembly independent of the insulation,
(c)masonry, or
(d)concrete.
(4)Combustible insulation with a flame-spread rating more than 25 but not more than 500 on any exposed surface, or any surface that would be exposed by cutting through the material in any direction, is permitted in the exterior walls of a building required to be of noncombustible construction that is not sprinklered and is more than 18 m high, measured from grade to the underside of the roof, provided the insulation is protected from adjacent space in the building, other than adjacent concealed spaces within wall assemblies, by a thermal barrier consisting of
(a)gypsum board not less than 12.7 mm thick, mechanically fastened to a supporting assembly independent of the insulation and with all joints either backed or taped and filled,
(b)lath and plaster, mechanically fastened to a supporting assembly independent of the insulation,
(c)masonry or concrete not less than 25 mm thick, or
(d)any thermal barrier that, when tested in conformance with CAN/ULC-S101, "Standard Method of Fire Endurance Tests of Building Construction and Materials," will not develop an average temperature rise more than 140°C or a maximum temperature rise more than 180°C at any point on its unexposed face within 10 min. (See Note A-3.1.5.14.(5)(d)) (See also Article 3.2.3.7.)
(5)Combustible insulation with a flame-spread rating more than 25 but not more than 500 on any exposed surface, or any surface that would be exposed by cutting through the material in any direction, is permitted in the interior walls, within ceilings and within roof assemblies of a building required to be of noncombustible construction that is not sprinklered and is more than 18 m high, measured from grade to the underside of the roof, provided the insulation is protected from adjacent space in the building, other than adjacent concealed spaces within wall assemblies, by a thermal barrier consisting of
(a)Type X gypsum board not less than 15.9 mm thick, mechanically fastened to a supporting assembly independent of the insulation and with all joints either backed or taped and filled, conforming to
(i)ASTM C1177 / C1177 M, "Standard Specification for Glass Mat Gypsum Substrate for Use as Sheathing,"
(ii)ASTM C1178 / C1178 M, "Standard Specification for Coated Glass Mat Water-Resistant Gypsum Backing Panel,"
(iii)ASTM C1396 / C1396 M, "Standard Specification for Gypsum Board,"
(iv)ASTM C1658 / C1658 M, "Standard Specification for Glass Mat Gypsum Panels," or
(v)CAN/CSA-A82.27-M, "Gypsum Board,"
(b)of non-loadbearing masonry or concrete not less than 50 mm thick,
(c)loadbearing masonry or concrete not less than 75 mm thick, or
(d)any thermal barrier that, when tested in conformance with CAN/ULC-S101, "Standard Method of Fire Endurance Tests of Building Construction and Materials,"
(i)does not develop an average temperature rise more than 140°C or a maximum temperature rise more than 180°C at any point on its unexposed face within 20 min, and
(ii)remains in place for not less than 40 min.
OBC Div. B 3.1.8.4. Determination of Ratings and Classifications
Open OBC Div. B 3.1.8.4. in the code viewer(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."
OBC Div. A 1.4.1.2.(1) Fire-protection rating
Open OBC Div. A 1.4.1.2.(1) in the code viewerFire-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.
OBC Div. B 3.1.8.10. Installation of Fire Dampers
Open OBC Div. B 3.1.8.10. in the code viewer(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))
OBC Div. B 3.1.9.2. Service Equipment Penetrations
Open OBC Div. B 3.1.9.2. in the code viewer(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.
OBC Div. B 3.2.5.12. Automatic Sprinkler Systems
Open OBC Div. B 3.2.5.12. in the code viewer(1)Except as provided by Sentences (2) to (4) and (9), an automatic sprinkler system shall be designed, constructed, installed and tested in conformance with NFPA 13, "Standard for the Installation of Sprinkler Systems." (See Note A-3.2.5.12.(1))
(2)Instead of the requirements of Sentence (1), NFPA 13R, "Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies," is permitted to be used for the design, construction, installation and testing of an automatic sprinkler system installed
(a)in a building of residential occupancy throughout that is not more than 4 storeys in building height and conforms to Article 3.2.2.47., 3.2.2.49., 3.2.2.51., 3.2.2.52. or 3.2.2.55.,
(b)in a building of Group B, Division 3 occupancy that contains sleeping accommodation for not more than 10 persons and not more than six occupants require assistance in evacuation in case of an emergency,
(c)in a building that contains a retirement home constructed in accordance with Article 3.2.2.55D., or
(d)in a building that contains a retirement home constructed in accordance with Article 3.2.2.55E., where the fire separation required by Sentence 3.3.4.11.(2) on the storey immediately below the roof assembly is continuous to the underside of the roof deck. (See Note A-3.2.5.12.(2))
(3)Instead of the requirements of Sentence (1), NFPA 13D, "Standard for the Installation of Sprinkler Systems in Oneand Two-Family Dwellings and Manufactured Homes," is permitted to be used for the design, construction and installation of an automatic sprinkler system installed
(a)in a building of residential occupancy throughout that contains not more than two dwelling units,
(b)reserved,
(c)in a building of residential occupancy throughout that contains more than two dwelling units, provided
(i)except for a secondary suite, no dwelling unit is located above another dwelling unit,
(ii)all suites are separated by a vertical fire separation having a fire-resistance rating of not less than 1 h that provides continuous protection from the top of the footing to the underside of the roof deck, with any space between the top of the wall and the roof deck tightly filled with mineral wool or noncombustible material,
(iii)each dwelling unit has its own sprinkler water supply provided in accordance with NFPA 13D, "Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes,"
(iv)a passive purge sprinkler system design is used as described in NFPA 13D, "Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes," and
(v)where the sprinkler system is taken into consideration for the reduction of limiting distance, all rooms, including closets, bathrooms and attached garages, that adjoin an exposing building face are sprinklered, notwithstanding any exemption stated in NFPA 13D, "Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes." (See Note A-3.2.5.12.(2))
(4)If a building contains fewer than 9 sprinklers, the water supply for these sprinklers is permitted to be supplied from the domestic water system for the building provided the required flow for the sprinklers can be met by the domestic system.
(5)If a water supply serves both an automatic sprinkler system and a system serving other equipment, control valves shall be provided so that either system can be shut off independently.
(6)Notwithstanding the requirements of the standards referenced in Sentences (1) and (2) for the installation of automatic sprinkler systems, sprinklers shall not be omitted in any room or closet in the storey immediately below a roof assembly. (See Note A-3.2.5.12.(6))
(7)Notwithstanding the requirements of the standards referenced in Sentences (1) and (2) regarding the installation of automatic sprinkler systems, in buildings conforming to Article 3.2.2.48., 3.2.2.51., 3.2.2.57., 3.2.2.60. or 3.2.2.93., sprinklers shall be provided for all balconies and decks, other than,
(a)balconies or decks that are not more than 610 mm in depth measured perpendicular to the exterior wall of the building, or
(b)decks on the uppermost roof of the building. (See Note A-3.2.5.12.(7))
(8)Sprinklers in elevator machine rooms shall have a temperature rating not less than that required for an intermediate temperature classification and shall be protected against physical damage. (See Note A-3.2.5.12.(8))
(9)Except as provided in Subsection 3.2.8., closely spaced sprinklers and associated draft stops need not be installed around floor openings in conformance with NFPA 13, "Standard for the Installation of Sprinkler Systems."
(10)The sprinkler system described in Sentence (3) shall be provided with a minimum 20 min water supply when installed in a retirement home.