Last updated
Values this chapter turns on
- max outside diameter, enclosed non-metallic raceway
- 175 mm
- max outside diameter, enclosed non-metallic raceway
- clearance to power lines over 750 V up to 46 kV
- 3 m
- clearance to power lines over 750 V up to 46 kV
- conductor swing to assume when it is unknown
- 1.8 m
- conductor swing to assume when it is unknown
- gypsum thermal barrier over combustible insulation
- 12.7 mm
- gypsum thermal barrier over combustible insulation
Section 3.1 decides two things a services reviewer checks on almost every Part 3 permit: what the building is (its major occupancy), and which combustible service materials can go into it. Wiring, cable, raceways, duct linings, pipes and insulation all carry combustible plastics, and the code lets them in under specific flame and smoke limits. Most questions here are lookups of a single number (175 mm, 1.5 m, 9 m, 25, 50 mm) or a single test rating (FT1, FT4, FT6).
Major occupancy classification
Every building or part of a building is classified by its major occupancy into one of the Groups and Divisions of the classification table, and a building used for several major occupancies is classified for each of them OBC Div. B 3.1.2.1.OBC Div. B 3.1.2.1. Classification of Buildings(1) Except as permitted by Articles 3.1.2.3. to 3.1.2.7., every building or part thereof shall be classified according to its major occupancy as belonging to one of the Groups or Divisions described in Table 3.1.2.1. (See Note A-3.1.2.1.(1)) (2) A building intended for use by more than one major occupancy shall be…. If all uses fall in the same Group (or the same Division where a Group is divided), the building is treated as a single major occupancy OBC Div. B 3.1.2.2.OBC Div. B 3.1.2.2. Occupancies of the Same Classification(1) Any building is deemed to be occupied by a single major occupancy, notwithstanding its use for more than one major occupancy, provided that all occupancies are classified as belonging to the same Group classification or, where the Group is divided into Divisions, as belonging to the same Division classification….
| Group | What it covers (short form) |
|---|---|
| A (Divisions 1 to 4) | Assembly: performing arts, other assembly, arena type, open air |
| B (Divisions 1 to 3) | Detention, care and treatment, care |
| C | Residential |
| D | Business and personal services |
| E | Mercantile |
| F (Divisions 1 to 3) | High-, medium- and low-hazard industrial |
A few special rules reclassify common cases:
| Use | Classification |
|---|---|
| Arena used now and then for trade shows | Group A, Division 3 OBC Div. B 3.1.2.3.OBC Div. B 3.1.2.3. Arena-Type Buildings(1) An arena-type building intended for occasional use for trade shows and similar exhibition purposes shall be classified as Group A, Division 3 occupancy. |
| Police station with detention quarters, 1 storey and 600 m² or less | May be Group B, Division 2 OBC Div. B 3.1.2.4.OBC Div. B 3.1.2.4. Police Stations(1) A police station with detention quarters is permitted to be classified as a Group B, Division 2 major occupancy provided the station is not more than 1 storey in building height and 600 m² in building area. |
| Group B, Division 3 suite: single housekeeping unit, sleeping for 10 or fewer, at most 2 needing evacuation help | May be Group C OBC Div. B 3.1.2.5.OBC Div. B 3.1.2.5. Group B, Division 3 Occupancies(1) Group B, Division 3 occupancies are permitted to be classified as Group C major occupancies within the application of Part 3 provided (a) the occupants live as a single housekeeping unit in a suite with sleeping accommodation for not more than 10 persons, and (b) not more than two occupants require assistance in… |
| Storage of baled combustible fibres | Medium-hazard industrial OBC Div. B 3.1.2.6.OBC Div. B 3.1.2.6. Storage of Combustible Fibres(1) Buildings or parts of thereof used for the storage of baled combustible fibres shall be classified as medium-hazard industrial occupancies. |
| Restaurant for 30 persons or fewer | May be Group E OBC Div. B 3.1.2.7.OBC Div. B 3.1.2.7. Restaurants(1) A restaurant is permitted to be classified as a Group E major occupancy within the application of Part 3 provided the restaurant is designed to accommodate not more than 30 persons consuming food or drink. |
Wires, cables and raceways
The rules come in two parallel sets: Article 3.1.4.3. for buildings permitted to be of combustible construction, and Article 3.1.5.21. for buildings required to be of noncombustible construction. The test ratings get stricter as you move from ordinary spaces to plenums.
| Location | Combustible construction | Noncombustible construction |
|---|---|---|
| General building | FT1 rating, or in an enclosed raceway, masonry wall or concrete slab OBC Div. B 3.1.4.3.OBC Div. B 3.1.4.3. Wires and Cables(1) Except as required by Sentence (2), optical fibre cables and electrical wires and cables with combustible insulation, jackets or sheathes installed in a building permitted to be of combustible construction shall (a) not convey flame or continue to burn for more than 1 min when tested in conformance with the… | FT4 rating, or in a raceway, masonry, concrete slab or a 1 h service room; or service-entry communication cable 3 m long or less OBC Div. B 3.1.5.21.OBC Div. B 3.1.5.21. Wires and Cables(1) Except as permitted by Sentence (2) and Articles 3.1.5.22. and 3.1.5.25., optical fibre cables and electrical wires and cables with combustible insulation, jackets or sheathes are permitted in a building required to be of noncombustible construction, provided (a) the wires and cables exhibit a vertical char of not… |
| Plenum, voice/sound/data cable not in a noncombustible raceway | FT6 | FT6 |
| Exposed wiring within 9 m of a plenum fed by noncombustible raceways | FT4 | FT4 |
| Fire alarm signal cable in a plenum | Exempt from the plenum rule | Exempt from the plenum rule |
FT6 means a horizontal flame distance of not more than 1.5 m with low average and peak smoke densities under CAN/ULC-S102.4. FT4 is a vertical char of 1.5 m or less in the cable tray test. The exam asks which rating applies where, not how the test is run.
Non-metallic raceways. In a noncombustible building, a totally enclosed non-metallic raceway inside a fire compartment may be up to 175 mm in outside diameter (or the equivalent rectangular area). Its required rating depends on the cable inside: FT4-rated cable needs a raceway with at least an FT4 rating, and cable below FT4 needs a raceway with a vertical char of 1.5 m or less in the conduit test. In a plenum the raceway itself needs FT6 performance OBC Div. B 3.1.5.23.OBC Div. B 3.1.5.23. Non-metallic Raceways(1) Except as required in Sentence (2), subject to the limits on the size of elements that penetrate fire separations when complying with Article 3.1.9.2., within a fire compartment of a building required to be of noncombustible construction, totally enclosed non-metallic raceways not more than 175 mm in outside…. In a combustible building, a non-metallic raceway in a plenum must meet the FT4 raceway clause OBC Div. B 3.1.4.4.OBC Div. B 3.1.4.4. Non-metallic Raceways(1) Totally enclosed non-metallic raceways used in a plenum in a building permitted to be of combustible construction shall meet the requirements of Clause 3.1.5.23.(1)(a)..
Other wiring cases. Wiring below a raised computer room floor in a noncombustible building needs FT1, which is also met by FT4 or FT6 cable OBC Div. B 3.1.5.25.OBC Div. B 3.1.5.25. Wires in Computer Room Floors(1) Optical fibre cables and electrical wires and cables with combustible insulation, jackets or sheathes, located in the space below a raised floor in a computer room, are permitted in a building required to be of noncombustible construction provided they do not convey flame or continue to burn for more than 1 min…. Combustible travelling cables on elevators are simply permitted OBC Div. B 3.1.5.22.OBC Div. B 3.1.5.22. Combustible Travelling Cables for Elevators(1) Combustible travelling cables are permitted on elevating devices in a building required to be of noncombustible construction..
Combustible insulation, ducts and piping
Insulation in a building required to be noncombustible 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…:
| Flame-spread rating | Condition |
|---|---|
| 25 or less | Permitted, no protection needed |
| Over 25 to 500 | Protected by a thermal barrier: 12.7 mm gypsum board fastened independently, lath and plaster, masonry or concrete |
| Any | Above roof decks, outside foundation walls below ground, under slabs-on-ground |
In an unsprinklered building over 18 m high the barriers get heavier: interior walls, ceilings and roofs need 15.9 mm Type X board or 50 mm non-loadbearing masonry or concrete (75 mm if loadbearing). Foamed plastic insulation goes to Article 3.1.5.15. instead.
Ducts. Combustible ducts, plenums and duct connectors are allowed in a noncombustible building only in horizontal runs. Duct linings, coverings, insulation, vibration isolation connectors, tape and pipe insulation must meet Subsection 3.6.5. A ventilation-only duct system kept entirely within a dwelling unit escapes two of the 3.6.5.1. limits OBC Div. B 3.1.5.18.OBC Div. B 3.1.5.18. Combustible Ducts(1) Except as required by Sentence 3.6.4.3.(1), combustible ducts, including plenums and duct connectors, are permitted to be used in a building required to be of noncombustible construction provided these ducts and duct connectors are used only in horizontal runs. (2) Combustible duct linings, duct coverings, duct….
Piping. Combustible piping and tubing (with its adhesives) is allowed if, where exposed, it has a flame-spread rating of 25 or less, and in a high building also a smoke developed classification of 50 or less. Concealment in a wall or concrete floor slab removes those limits. Combustible sprinkler piping is allowed inside a sprinklered floor area. Polypropylene for corrosive waste or for distilled or dialyzed water in laboratories and hospitals is allowed if the building is sprinklered throughout, the pipe is not in a vertical shaft, and penetrations have FT-rated firestops tested at a 50 Pa pressure difference OBC Div. B 3.1.5.19.OBC Div. B 3.1.5.19. Combustible Piping Materials(1) Except as permitted by Clause 3.1.5.2.(1)(d) and Article 3.1.5.25. and Sentences (2) and (3), combustible piping and tubing and associated adhesives are permitted to be used in a building required to be of noncombustible construction provided that, except when concealed in a wall or concrete floor slab, they (a)….
Other combustible components and above ground conductors
Minor combustible components allowed in a noncombustible building include paint, sealants between exterior wall components, firestops and fire blocks, pneumatic control tubing of 10 mm outside diameter or less, adhesives and vapour barriers, outlet and junction boxes, and wood blocking for windows or wall-mounted items OBC Div. B 3.1.5.2.OBC Div. B 3.1.5.2. Minor Combustible Components(1) The following minor combustible components are permitted in a building required to be of noncombustible construction: (a) paint, (See also Clause 3.1.13.1.(2)(b)) (b) self-adhesive tapes, mastics and caulking materials including foamed plastic air sealants, applied to provide a seal between the major components of…. Combustible pool and spa parts are allowed OBC Div. B 3.1.5.26.OBC Div. B 3.1.5.26. Combustible Components in Public Pools and Public Spas(1) Combustible fittings and components in a public pool or public spa, including main drains, piping, skimmers, return inlets, steps, ladder rungs and liners, are permitted in a building required to be of noncombustible construction., and so is a combustible solar collector system above the roof OBC Div. B 3.1.5.28.OBC Div. B 3.1.5.28. Combustible Solar Collector Systems(1) A combustible solar collector system is permitted to be installed above the roof of a building required to be of noncombustible construction..
Overhead power lines. A building must not be placed beneath existing above ground conductors, and horizontal clearance is measured from the conductor's maximum swing to the building or any accessible projection such as a balcony OBC Div. B 3.1.20.1.OBC Div. B 3.1.20.1. Clearance to Buildings(1) A building shall not be located beneath existing above ground electrical conductors. (2) The horizontal clearance measured from the maximum conductor swing to the building, including balconies, fire escapes, flat roofs or other accessible projections beyond the face of the building, shall, (a) be not less than 1…:
| Conductor voltage | Minimum horizontal clearance |
|---|---|
| 750 V or less | 1 m (except at the service connection) |
| Over 750 V to 46 kV | 3 m |
| Over 46 kV to 69 kV | 3.7 m |
| Over 69 kV | Per CAN/CSA-C22.3 No.1 |
Where the swing of a privately owned conductor is unknown, assume at least 1.8 m.
Common traps
- FT6 is the plenum rating; FT4 is the general rating in noncombustible buildings; FT1 is the general rating in combustible buildings.
- Fire alarm signal cables in plenums are exempt from the FT6 rule.
- Combustible ducts in a noncombustible building: horizontal runs only.
- The 175 mm raceway limit applies within a fire compartment, and penetrations are still governed by 3.1.9.2.
- Clearance to power lines is measured from the maximum swing, not the resting position.
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.
- Major occupancy classification
Every building or part of a building is classified by its major occupancy into one of the Groups and Divisions of the classification table, and a building used for several major…
- Wires, cables and raceways
The rules come in two parallel sets: Article 3.1.4.3. for buildings permitted to be of combustible construction, and Article 3.1.5.21. for buildings required to be of…
- Combustible insulation, ducts and piping
In an unsprinklered building over 18 m high the barriers get heavier: interior walls, ceilings and roofs need 15.9 mm Type X board or 50 mm non-loadbearing masonry or concrete (75…
- Other combustible components and above ground conductors
Minor combustible components allowed in a noncombustible building include paint, sealants between exterior wall components, firestops and fire blocks, pneumatic control tubing of…
Usual exam traps
- FT6 is the plenum rating; FT4 is the general rating in noncombustible buildings; FT1 is the general rating in combustible buildings.
- Fire alarm signal cables in plenums are exempt from the FT6 rule.
- Combustible ducts in a noncombustible building: horizontal runs only.
- The 175 mm raceway limit applies within a fire compartment, and penetrations are still governed by 3.1.9.2.
- Clearance to power lines is measured from the maximum swing, not the resting position.
Practice this chapter
Questions on Classification and combustible service components (3.1), 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 3.1.2.1. Classification of Buildings
Open OBC Div. B 3.1.2.1. in the code viewer(1)Except as permitted by Articles 3.1.2.3. to 3.1.2.7., every building or part thereof shall be classified according to its major occupancy as belonging to one of the Groups or Divisions described in Table 3.1.2.1. (See Note A-3.1.2.1.(1))
(2)A building intended for use by more than one major occupancy shall be classified according to all major occupancies for which it is used or intended to be used.
OBC Div. B 3.1.2.2. Occupancies of the Same Classification
Open OBC Div. B 3.1.2.2. in the code viewer(1)Any building is deemed to be occupied by a single major occupancy, notwithstanding its use for more than one major occupancy, provided that all occupancies are classified as belonging to the same Group classification or, where the Group is divided into Divisions, as belonging to the same Division classification described in Table 3.1.2.1.
OBC Div. B 3.1.2.3. Arena-Type Buildings
Open OBC Div. B 3.1.2.3. in the code viewer(1)An arena-type building intended for occasional use for trade shows and similar exhibition purposes shall be classified as Group A, Division 3 occupancy.
OBC Div. B 3.1.2.4. Police Stations
Open OBC Div. B 3.1.2.4. in the code viewer(1)A police station with detention quarters is permitted to be classified as a Group B, Division 2 major occupancy provided the station is not more than 1 storey in building height and 600 m² in building area.
OBC Div. B 3.1.2.5. Group B, Division 3 Occupancies
Open OBC Div. B 3.1.2.5. in the code viewer(1)Group B, Division 3 occupancies are permitted to be classified as Group C major occupancies within the application of Part 3 provided
(a)the occupants live as a single housekeeping unit in a suite with sleeping accommodation for not more than 10 persons, and
(b)not more than two occupants require assistance in evacuation in case of an emergency.
OBC Div. B 3.1.2.6. Storage of Combustible Fibres
Open OBC Div. B 3.1.2.6. in the code viewer(1)Buildings or parts of thereof used for the storage of baled combustible fibres shall be classified as medium-hazard industrial occupancies.
OBC Div. B 3.1.2.7. Restaurants
Open OBC Div. B 3.1.2.7. in the code viewer(1)A restaurant is permitted to be classified as a Group E major occupancy within the application of Part 3 provided the restaurant is designed to accommodate not more than 30 persons consuming food or drink.
OBC Div. B 3.1.4.3. Wires and Cables
Open OBC Div. B 3.1.4.3. in the code viewer(1)Except as required by Sentence (2), optical fibre cables and electrical wires and cables with combustible insulation, jackets or sheathes installed in a building permitted to be of combustible construction shall
(a)not convey flame or continue to burn for more than 1 min when tested in conformance with the Vertical Flame Test (FT1 rating) in CSA C22.2 No. 0.3, "Test Methods for Electrical Wires and Cables," or
(b)be located in
(i)totally enclosed noncombustible raceways, (See Note A-3.1.4.3.(1)(b)(i))
(ii)masonry walls,
(iii)concrete slabs, or
(iv)totally enclosed non-metallic raceways conforming to Clause 3.1.5.23.(1)(b). (See Note A-3.1.4.3.(1)) (See also Sentence 3.6.4.3.(1))
(2)Except as permitted in Sentences (3) and (4), optical fibre cables and electrical wires and cables with combustible insulation, jackets or sheathes that are used for the transmission of voice, sound or data and are installed in a plenum in a building permitted to be of combustible construction shall exhibit the following characteristics when tested in conformance with CAN/ULC-S102.4, "Standard Method of Test for Fire and Smoke Characteristics of Electrical Wiring, Cables and Non-Metallic Raceways," (FT6 rating):
(a)a horizontal flame distance of not more than 1.5 m,
(b)an average optical smoke density of not more than 0.15, and
(c)a peak optical smoke density of not more than 0.5.
(3)Except as permitted in Sentence (4), where totally enclosed noncombustible raceways are used in a plenum, exposed components of wiring systems with combustible insulation, jackets or sheathes, including optical fibre cables and electrical wires and cables that are used for the transmission of voice, sound or data, that are installed in the plenum or that extend not more than 9 m from the plenum, including drop down to the floor level, are permitted, provided they exhibit a vertical char of not more than 1.5 m when tested in conformance with the Vertical Flame Test-Cables in Cable Trays (FT4 rating) in CSA C22.2 No. 0.3, "Test Methods for Electrical Wires and Cables."
(4)Cables or wires within plenums that are used for the transmission of signals in fire alarm systems need not comply with the requirements of Sentence (2).
Show all 20 articles
OBC Div. B 3.1.5.21. Wires and Cables
Open OBC Div. B 3.1.5.21. in the code viewer(1)Except as permitted by Sentence (2) and Articles 3.1.5.22. and 3.1.5.25., optical fibre cables and electrical wires and cables with combustible insulation, jackets or sheathes are permitted in a building required to be of noncombustible construction, provided
(a)the wires and cables exhibit a vertical char of not more than 1.5 m when tested in conformance with the Vertical Flame Test-Cables in Cable Trays (FT4 rating) in CSA C22.2 No. 0.3, "Test methods for electrical wires and cables,"
(b)the wires and cables are located in
(i)totally enclosed noncombustible raceways, (See Note A-3.1.4.3.(1)(b)(i))
(ii)masonry walls.
(iii)concrete slabs,
(iv)a service room separated from the remainder of the building by a fire separation having a fire-resistance rating not less than 1 h, or
(v)totally enclosed non-metallic raceways conforming to Clause 3.1.5.23.(1)(b), or
(c)the wires and cables are communication cables used at the service entry to a building and are not more than 3 m long. (See Note A-3.1.5.21.(1))
(2)Except as permitted in Sentences (3) and (4), optical fibre cables and electrical wires and cables with combustible insulation, jackets or sheathes that are used for the transmission of voice, sound or data and are not located in totally enclosed noncombustible raceways are permitted to be installed in a plenum in a building required to be of noncombustible construction, provided the wires and cables exhibit a horizontal flame distance of not more than 1.5 m, an average optical smoke density of not more than 0.15, and a peak optical smoke density of not more than 0.5 when tested in conformance with CAN/ULC-S102.4, "Standard Method of Test for Fire and Smoke Characteristics of Electrical Wiring, Cables and Non-Metallic Raceways," (FT6 rating).
(3)Except as permitted in Sentence (4), where totally enclosed noncombustible raceways are used in a plenum, exposed components of wiring systems with combustible insulation, jackets or sheathes, including optical fibre cables and electrical wires and cables that are used for the transmission of voice, sound or data, that are installed in the plenum or that extend not more than 9 m from the plenum including drop down to the floor level, are permitted provided they exhibit a vertical char of not more than 1.5 m when tested in conformance with the Vertical Flame Test-Cables in Cable Trays (FT4 rating) in CSA C22.2 No. 0.3, "Test methods for electrical wires and cables."
(4)Cables or wires within plenums that are used for the transmission of signals in fire alarm systems need not comply with the requirements of Sentences (2) and (3).
OBC Div. B 3.1.5.23. Non-metallic Raceways
Open OBC Div. B 3.1.5.23. in the code viewer(1)Except as required in Sentence (2), subject to the limits on the size of elements that penetrate fire separations when complying with Article 3.1.9.2., within a fire compartment of a building required to be of noncombustible construction, totally enclosed non-metallic raceways not more than 175 mm in outside diameter, or of an equivalent rectangular area, are permitted to be used to enclose optical fibre cables and electrical wires and cables, provided
(a)where the wires and cables in the raceways meet or exceed the requirements of Clause 3.1.5.21.(1)(a), the non-metallic raceways meet the requirements for at least an FT4 rating in,
(i)CAN/CSA-C22.2 No. 262, "Optical Fiber Cable and Communication Cable Raceway Systems," or
(ii)CAN/ULC-S143, "Standard Method of Fire Tests for Non-Metallic Electrical and Optical Fibre Cable Raceway Systems," and
(b)where the wires and cables in the raceways do not meet or exceed the requirements of Clause 3.1.5.21.(1)(a), the non-metallic raceways exhibit a vertical char of not more than 1.5 m when tested in conformance with the Vertical Flame Test (FT4)-conduit or Tubing on Cable Tray in Clause 6.16 of CSA C22.2 No. 211.0, "General Requirements and Methods of Testing for Nonmetallic Conduit."
(2)Totally enclosed non-metallic raceways used in a plenum in a building required to be of noncombustible construction shall exhibit a horizontal flame distance of not more than 1.5 m, an average optical smoke density of not more than 0.15, and a peak optical smoke density of not more than 0.5 when tested in conformance with CAN/ULC-S102.4, "Standard Method of Test for Fire and Smoke Characteristics of Electrical Wiring, Cables and Non-Metallic Raceways," (FT6 rating).
OBC Div. B 3.1.4.4. Non-metallic Raceways
Open OBC Div. B 3.1.4.4. in the code viewer(1)Totally enclosed non-metallic raceways used in a plenum in a building permitted to be of combustible construction shall meet the requirements of Clause 3.1.5.23.(1)(a).
OBC Div. B 3.1.5.25. Wires in Computer Room Floors
Open OBC Div. B 3.1.5.25. in the code viewer(1)Optical fibre cables and electrical wires and cables with combustible insulation, jackets or sheathes, located in the space below a raised floor in a computer room, are permitted in a building required to be of noncombustible construction provided they do not convey flame or continue to burn for more than 1 min when tested in conformance with the Vertical Flame Test in Clause 4.11.1. of CSA C22.2 No. 0.3, "Test methods for electrical wires and cables," (FT1 Rating).
(2)The requirement in Sentence (1) is considered to be met where the wires and cables
(a)exhibit a vertical char of not more than 1.5 m when tested in conformance with the Vertical Flame Test-Cables in Cabletrough in Clause 4.11.4. of CSA C22.2 No. 0.3, "Test methods for electrical wires and cables," (FT4 Rating), or
(b)exhibit a flame-spread of not more than 1.5 m, a smoke density of not more than 0.5 at peak optical density and a smoke density not more than 0.15 at average optical density when tested in conformance with the Flame and Smoke Test in the Appendix to CSA C22.2 No. 0.3, "Test methods for electrical wires and cables," (FT6 Rating).
OBC Div. B 3.1.5.22. Combustible Travelling Cables for Elevators
Open OBC Div. B 3.1.5.22. in the code viewer(1)Combustible travelling cables are permitted on elevating devices in a building required to be of noncombustible construction.
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 3.1.5.18. Combustible Ducts
Open OBC Div. B 3.1.5.18. in the code viewer(1)Except as required by Sentence 3.6.4.3.(1), combustible ducts, including plenums and duct connectors, are permitted to be used in a building required to be of noncombustible construction provided these ducts and duct connectors are used only in horizontal runs.
(2)Combustible duct linings, duct coverings, duct insulation, vibration isolation connectors, duct tape, pipe insulation and pipe coverings are permitted to be used in a building required to be of noncombustible construction provided they conform to the appropriate requirements of Subsection 3.6.5.
(3)In a building required to be of noncombustible construction, combustible ducts need not comply with the requirements of Sentences 3.6.5.1.(1) and (2) provided the ducts are
(a)part of a duct system conveying only ventilation air, and
(b)contained entirely within a dwelling unit.
OBC Div. B 3.1.5.19. Combustible Piping Materials
Open OBC Div. B 3.1.5.19. in the code viewer(1)Except as permitted by Clause 3.1.5.2.(1)(d) and Article 3.1.5.25. and Sentences (2) and (3), combustible piping and tubing and associated adhesives are permitted to be used in a building required to be of noncombustible construction provided that, except when concealed in a wall or concrete floor slab, they
(a)have a flame-spread rating not more than 25, and
(b)if used in a building described in Subsection 3.2.6., have a smoke developed classification not more than 50.
(2)Combustible sprinkler piping is permitted to be used within a sprinklered floor area in a building required to be of noncombustible construction. (See also Article 3.2.5.13.)
(3)Polypropylene pipes and fittings are permitted to be used for drain, waste and vent piping for the conveyance of highly corrosive materials and for piping used to distribute distilled or dialyzed water in laboratory and hospital facilities in a building required to be of noncombustible construction, provided
(a)the building is sprinklered throughout,
(b)the piping is not located in a vertical shaft, and
(c)piping that penetrates a fire separation is 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," with a pressure differential of 50 Pa between the exposed and unexposed sides, with the higher pressure on the exposed side.
OBC Div. B 3.1.5.2. Minor Combustible Components
Open OBC Div. B 3.1.5.2. in the code viewer(1)The following minor combustible components are permitted in a building required to be of noncombustible construction:
(a)paint, (See also Clause 3.1.13.1.(2)(b))
(b)self-adhesive tapes, mastics and caulking materials including foamed plastic air sealants, applied to provide a seal between the major components of exterior wall construction, (See also Article 3.6.4.3. for limits on the use of combustible materials in plenum spaces),
(c)firestops and fire blocks conforming to Sentence 3.1.9.1.(1) Article 3.1.11.7.,
(d)tubing for pneumatic controls provided it has an outside diameter not more than 10 mm,
(e)adhesives, vapour barriers and sheathing papers,
(f)electrical outlet and junction boxes,
(g)wood blocking intended for the attachment of window elements within exterior wall assemblies,
(h)wood blocking within wall assemblies intended for the attachment of handrails, fixtures, and similar items mounted on the surface of the wall, and
(i)similar minor components.
OBC Div. B 3.1.5.26. Combustible Components in Public Pools and Public Spas
Open OBC Div. B 3.1.5.26. in the code viewer(1)Combustible fittings and components in a public pool or public spa, including main drains, piping, skimmers, return inlets, steps, ladder rungs and liners, are permitted in a building required to be of noncombustible construction.
OBC Div. B 3.1.5.28. Combustible Solar Collector Systems
Open OBC Div. B 3.1.5.28. in the code viewer(1)A combustible solar collector system is permitted to be installed above the roof of a building required to be of noncombustible construction.
OBC Div. B 3.1.20.1. Clearance to Buildings
Open OBC Div. B 3.1.20.1. in the code viewer(1)A building shall not be located beneath existing above ground electrical conductors.
(2)The horizontal clearance measured from the maximum conductor swing to the building, including balconies, fire escapes, flat roofs or other accessible projections beyond the face of the building, shall,
(a)be not less than 1 m, for electrical conductors carrying voltages 750 V or less, except where necessary to connect to the electrical wiring of the building,
(b)be not less than 3 m, for electrical conductors carrying voltages greater than 750 V but not exceeding 46 kV,
(c)be not less than 3.7 m, for electrical conductors carrying voltages greater than 46 kV but not exceeding 69 kV, or
(d)conform to the requirements of CAN/CSA-C22.3 No.1, "Overhead Systems," for electrical conductors carrying voltages greater than 69 kV.
(3)Where the swing of an above ground electrical conductor not owned or operated by an electrical supply authority is not known, a swing of not less than 1.8 m shall be used.
(4)Sentences (1) to (3) do not apply to a building containing electrical equipment and electrical installations used exclusively in the generation, transformation or transmission of electrical power or energy intended for sale or distribution to the public.