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Ontario Building Code Matrix: How to Fill It In

How to fill in an Ontario Building Code matrix for a permit: Part 3 or Part 9, major occupancy, building area, classification, spatial separation and more.
building area limit for Part 9
600 m²
building area limit for Part 9
building height limit for Part 9
3 storeys
building height limit for Part 9
per sleeping room for occupant load
2 persons
per sleeping room for occupant load
the whole code analysis, line by line
1 page
the whole code analysis, line by line

Last updated

An Ontario Building Code matrix is the table on a set of permit drawings that sums up the code analysis: which Part of the code applies, the major occupancy, building area and height, the classification, sprinklers, fire alarm, occupant load, barrier-free design, fire-resistance ratings and spatial separation. Every line cites the article behind it. The first decision is Part 3 or Part 9, and Part 9 covers buildings of 3 storeys or less with a building area of not more than 600 m² in the listed occupancies (OBC Div. A 1.3.3.3.OBC Div. A 1.3.3.3. Application of Part 9(1) Subject to Article 1.3.3.3B., Part 9 of Division B applies to all buildings described in Article 1.1.1.1. of 3 storeys or less in building height, having a building area not exceeding 600 m², and used for major occupancies classified as (a) reserved (b) Group C, residential occupancies other than buildings used…).

The Building Code does not print a matrix form. Municipalities ask for one as part of a complete permit application, and a common form is used across the province for both Part 3 and Part 9 buildings. This page walks through the usual lines and where each answer comes from in the 2024 code. Your building department decides which form it wants and how the code applies to your project.

The matrix at a glance

Matrix line What you enter Where to look
Project description new building, addition, alteration or change of use Building Code Act s. 8
Part of the code Part 3 or Part 9 Div. A 1.3.3.2. and 1.3.3.3.
Major occupancy Group and Division, such as C or E Div. B 3.1.2.1.
Building area m², greatest area above grade Div. A 1.4.1.2.
Gross area m², all floors above grade Div. A 1.4.1.2.
Building height storeys above grade, and metres Div. A 1.4.1.2.; 3.2.1.1. or 9.10.4.1.
Streets facing number of streets the building faces Div. B 3.2.2.10.
Classification the Part 3 article, such as 3.2.2.50. Div. B 3.2.2.20. to 3.2.2.93.
Sprinklers required or not, and where the classification article
Standpipe required or not Div. B 3.2.5.8.
Fire alarm required or not Div. B 3.2.4.1. or 9.10.18.2.
Construction type combustible or noncombustible permitted the classification article; 3.1.4. and 3.1.5.
Occupant load persons per floor Div. B 3.1.17.1. or 9.9.1.3.
Barrier-free design required or not Div. B Section 3.8.
Fire-resistance ratings floors, roof, mezzanine, load-bearing supports classification article or 9.10.8.1.
Spatial separation limiting distance and openings, each wall Div. B 3.2.3. or 9.10.14.
Plumbing fixtures fixtures required Div. B 3.7.4.

This is our summary of the usual lines, not a copy of any municipal form. Read each article before you sign a matrix.

Line 1: Part 3 or Part 9

Everything else depends on this line. Part 9 applies to buildings of 3 storeys or less in building height, with a building area of not more than 600 m², used for residential (Group C, other than retirement homes), business and personal services (Group D), mercantile (Group E), or medium and low hazard industrial (Group F, Divisions 2 and 3) occupancies (Div. A 1.3.3.3.OBC Div. A 1.3.3.3. Application of Part 9(1) Subject to Article 1.3.3.3B., Part 9 of Division B applies to all buildings described in Article 1.1.1.1. of 3 storeys or less in building height, having a building area not exceeding 600 m², and used for major occupancies classified as (a) reserved (b) Group C, residential occupancies other than buildings used…).

Part 3 applies to post-disaster buildings, to assembly (Group A), care, care and treatment, and detention (Group B), and high hazard industrial (Group F, Division 1) buildings of any size, and to every other building that exceeds the Part 9 size limits (Div. A 1.3.3.2.OBC Div. A 1.3.3.2. Application of Parts 3, 4, 5 and 6(1) Subject to Articles 1.3.3.1A., 1.3.3.3B., Parts 3, 4, 5, and 6 of Division B apply to all buildings described in Article 1.1.1.1. and (a) classified as post-disaster buildings, (b) used for major occupancies classified as (i) Group A, assembly occupancies, (ii) Group B, care, care and treatment or detention…).

A Part 9 building can still pull in some Part 3 rules. Tents, elevators, transformer vaults and rooms for an assembly occupancy, among others, must follow Part 3 (9.10.1.3.OBC Div. B 9.10.1.3. Items Under Part 3 Jurisdiction(1) Tents, air-supported structures, transformer vaults, walkways, elevators and escalators shall conform to Part 3. (2) Where rooms or spaces are intended for an assembly occupancy, such rooms or spaces shall conform to Part 3. (3) Basements containing more than 1 storey or exceeding 600 m² in area shall conform to…). A restaurant seating area inside a Part 9 retail building is a common example.

Lines 2 to 5: occupancy, areas and height

Major occupancy. Classify every major occupancy in the building using Table 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…. A building with more than one major occupancy lists each one, and the separations between them come from 3.1.3.1.OBC Div. B 3.1.3.1. Separation of Major Occupancies(1) Except as permitted by Sentences (2) and (3), major occupancies shall be separated from adjoining major occupancies by fire separations having fire-resistance ratings conforming to Table 3.1.3.1. (2) In a building not more than 3 storeys in building height, if not more than two dwelling units are contained… in Part 3 or Subsection 9.10.9. in Part 9.

Building area and gross area. These two get mixed up more than any other lines. Building area is the greatest horizontal area of the building above grade, to the outside of the exterior walls or the centre line of a firewall (Div. A 1.4.1.2.OBC Div. A 1.4.1.2.(1) Building areaBuilding area means the greatest horizontal area of a building above grade within the outside surface of exterior walls or within the outside surface of exterior walls and the centre line of firewalls.). Gross area is the total of all floors above grade (Div. A 1.4.1.2.OBC Div. A 1.4.1.2.(1) Gross areaGross area means the total area of all floors above grade measured between the outside surfaces of exterior walls or between the outside surfaces of exterior walls and the centre line of firewalls, except that, in any occupancy other than a residential occupancy, where an access or a building service penetrates a…). A firewall splits one structure into separate buildings for these numbers, which is why firewalls appear on so many matrices (see our firewall and fire separations guide).

Building height. Building height in storeys counts the storeys between the roof and the floor of the first storey (Div. A 1.4.1.2.OBC Div. A 1.4.1.2.(1) Building height (in storeys)Building height (in storeys) means the number of storeys contained between the roof and the floor of the first storey.). The first storey is the one with its floor closest to grade and its ceiling more than 1.8 m above grade (Div. A 1.4.1.2.OBC Div. A 1.4.1.2.(1) First storeyFirst storey means the storey that has its floor closest to grade and its ceiling more than 1.8 m above grade.), so a basement that sticks well out of the ground can become the first storey. Mezzanines can be left out of the count if they stay within the limits in 3.2.1.1.OBC Div. B 3.2.1.1. Exceptions in Determining Building Height(1) A rooftop enclosure provided for elevator machinery, a stairway or a service room used for no purpose other than for service to the building, shall not be considered as a storey in calculating the building height. (2) Space under tiers of seats in a building of the arena type shall not be considered as adding to… or 9.10.4.1.OBC Div. B 9.10.4.1. Mezzanines Not Considered as Storeys(1) Except as required by Sentences (2) and 9.10.4.2.(1), the space above a mezzanine is permitted to be excluded from the calculation of building height, provided (a) the aggregate area of mezzanines that are not superimposed does not exceed 10% of the floor area of the building in which they are located, and (b) the….

Building height in metres matters too: a Part 3 building past certain heights is a high building with extra requirements (3.2.6.1.OBC Div. B 3.2.6.1. Application(1) Except as provided in Sentence (2), this Subsection applies to a building (a) of Group A, D, E or F major occupancy classification that is more than (i) 36 m high, measured between grade and the floor level of the top storey, or (ii) 18 m high, measured between grade and the floor level of the top storey, and in…).

Lines 6 to 10: classification and fire protection (Part 3)

For a Part 3 building, find the article in Subsection 3.2.2. that fits the major occupancy, building height, building area, number of streets faced and sprinkler status. The articles run from 3.2.2.20.OBC Div. B 3.2.2.20. Group A, Division 1, Any Height, Any Area, Sprinklered(1) Except as permitted by Articles 3.2.2.21. and 3.2.2.22., a building classified as Group A, Division 1 shall conform to Sentence (2). (2) Except as permitted by Article 3.2.2.16., the building referred to in Sentence (1) shall be of noncombustible construction, and (a) except as permitted by Sentences 3.2.2.7.(1)… onward, grouped by occupancy. Each one tells you:

  • whether the building must be sprinklered,
  • whether it may be of combustible construction or must be noncombustible,
  • the fire-resistance ratings for floors, roofs, mezzanines and the load-bearing walls, columns and arches that support them.

The streets facing count comes from 3.2.2.10.OBC Div. B 3.2.2.10. Streets(1) Every building shall face a street located in conformance with the requirements of Articles 3.2.5.4 and 3.2.5.5 for access routes. (2) For the purposes of Subsections 3.2.2. and 3.2.5. an access route conforming to Subsection 3.2.5. is permitted to be considered as a street. (3) A building conforming to Article…, and in a building with more than one major occupancy, the height and area of the whole building are used to choose the article for each occupancy (3.2.2.5.OBC Div. B 3.2.2.5. Applicable Building Height and Area(1) In determining the fire safety requirements of a building in relation to each of the major occupancies contained therein, the building height and building area of the entire building shall be used. (2) For the purposes of Sentence (1), a retirement home is deemed to be a separate major occupancy.).

Then fill in the systems: a fire alarm system if 3.2.4.1.OBC Div. B 3.2.4.1. Determination of Requirement for a Fire Alarm System(1) Except as permitted in Sentences (2) and (3), a fire alarm system shall be installed in buildings in which an automatic sprinkler system is installed. (2) Buildings in which a sprinkler system is installed in accordance with NFPA 13D, "Standard for the Installation of Sprinkler Systems in One- and Two-Family… requires one, and a standpipe system if the building is over the height or area thresholds in 3.2.5.8.OBC Div. B 3.2.5.8. Standpipe Systems(1) Except as permitted by Sentence (2), a standpipe system shall be installed in a building that is (a) more than 3 storeys in building height, (b) more than 14 m high measured between grade and the ceiling of the top storey, or (c) not more than 14 m high measured between grade and the ceiling of the top storey but….

Lines 6 to 10: the Part 9 version

A Part 9 matrix is shorter. There is no classification article. Instead:

  • Fire-resistance ratings for floors and roofs come from Table 9.10.8.1.OBC Div. B 9.10.8.1. Fire-Resistance Ratings for Floors and Roofs(1) Except as otherwise provided in this Subsection, the fire-resistance ratings of floors and roofs shall conform to Table 9.10.8.1. (See Subsection 9.10.2. for mixed occupancies and Subsection 9.10.21. for construction camps.) by occupancy.
  • Fire alarm is required in a building with more than 3 storeys including storeys below the first storey, where the total occupant load exceeds 300, and in the other cases in 9.10.18.2.OBC Div. B 9.10.18.2. Fire Alarm System Required(1) Reserved. (2) Except as provided in Sentence (5), a fire alarm system shall be installed (a) in every building that contains more than 3 storeys, including storeys below the first storey, (b) where the total occupant load exceeds 300, or (c) when the occupant load for any major occupancy in Table 9.10.18.2. is….
  • Fire department access follows 9.10.20.3.OBC Div. B 9.10.20.3. Fire Department Access to Buildings(1) Access for fire department equipment shall be provided to each building by means of a street, private roadway or yard. (See Note A-9.10.20.3.(1) and A-3.2.5.6.(1)) (2) Where access to a building as required in Sentence (1) is provided by means of a roadway or yard, the design and location of such roadway or yard….

Lines 11 and 12: occupant load and barrier-free design

Occupant load. In a dwelling unit, count 2 persons per sleeping room. For other spaces, use the number of persons the space is designed for, but not fewer than the table values per square metre (3.1.17.1.OBC Div. B 3.1.17.1. Occupant Load Determination(1) The occupant load of a floor area or part of a floor area, shall be based on (a) the number of seats in an assembly occupancy having fixed seats, (b) 2 persons per sleeping room in a dwelling unit, or (c) the number of persons for which the area is designed, but not less than that determined from Table 3.1.17.1…, 9.9.1.3.OBC Div. B 9.9.1.3. Occupant Load(1) The occupant load of a floor area or part of a floor area shall be based on (a) two persons per sleeping room or sleeping area in a dwelling unit or suite, and (b) for occupancies other than as described in Clause (a), the number of persons (i) for which the area is designed, or (ii) determined from Table 3.1.17.1.). Occupant load drives exit widths, the number of exits, plumbing fixture counts and, in Part 9, the fire alarm trigger.

Barrier-free design. Section 3.8. sets where a barrier-free path of travel and barrier-free entrances are required (3.8.1.1.OBC Div. B 3.8.1.1. Application(1) The requirements of this Section apply to all buildings except (a) detached houses, semi-detached houses, houses with a secondary suite, duplexes, triplexes, townhouses, row houses and boarding or rooming houses with fewer than 8 boarders or roomers, (See Note A-1.4.1.2.(1) of Division A, Secondary Suite) (b)…, 3.8.2.1.OBC Div. B 3.8.2.1. Areas Requiring Barrier-Free Path of Travel(1) Except as permitted by Sentence (3), a barrier-free path of travel from the entrances required by Sentences 3.8.1.2.(1) and (2) to be barrier-free shall be provided (a) throughout the entrance storey, and (b) within all normally occupied floor areas and rooftop amenity spaces, unless as permitted by Sentence (2)…). Houses are among the buildings it does not apply to, but most other new buildings must comply. Our barrier-free accessibility guide covers the details.

Line 13: spatial separation

This line is filled in for each wall. For every exposing building face, note the limiting distance (to the property line, the centre line of a street, or an imaginary line between buildings on the same property) (Div. A 1.4.1.2.OBC Div. A 1.4.1.2.(1) Limiting distanceLimiting distance means the distance from an exposing building face to a property line, the centre line of a street, lane or public thoroughfare, or to an imaginary line between 2 buildings or fire compartments on the same property, measured at right angles to the exposing building face.), the area of the face, the permitted and proposed percentage of unprotected openings, and the required fire-resistance rating and cladding.

The rules are in Subsection 3.2.3. for Part 3 (3.2.3.1.OBC Div. B 3.2.3.1. Limiting Distance and Area of Unprotected Openings(1) Except as permitted by Articles 3.2.3.10. to 3.2.3.12., the area of unprotected openings in an exposing building face for the applicable limiting distance shall be not more than the value determined in accordance with (a) Table 3.2.3.1.-B or Table 3.2.3.1.-C for an exposing building face conforming to Article…, 3.2.3.7.OBC Div. B 3.2.3.7. Construction of Exposing Building Face(1) Except as provided by Sentences (3) and (4) and Articles 3.2.3.10. and 3.2.3.11., the fire-resistance rating, construction and cladding for exposing building faces of buildings or fire compartments of Group A, B, C, D or Group F, Division 3 occupancy classification shall comply with Table 3.2.3.7. (2) Except as…) and Subsection 9.10.14. for Part 9 (9.10.14.4.OBC Div. B 9.10.14.4. Openings in Exposing Building Face(1) Except as provided in Sentences (6) to (10) and Sentence 9.10.14.6.(1), the maximum aggregate area of unprotected openings in an exposing building face shall (a) conform to Table 9.10.14.4., (b) conform to Subsection 3.2.3., or (c) where the limiting distance is not less than 1.2 m, be equal to or less than (i)…). Spatial separation is the line plans examiners send back most often, so show the calculation on the drawings.

Line 14: plumbing fixtures

List the water closets, lavatories and other fixtures required for the occupant load. Part 3 buildings use 3.7.4.OBC Div. B 3.7.4.2. Plumbing Fixtures, General(1) Except as provided in Sentence (2), for the purposes of this Subsection, the occupant load shall be determined in accordance with the provisions in Subsection 3.1.17. except that in a Group D occupancy, the area per person shall be 14 m². (See Note A-3.7.4.2.(1)) (2) For the purpose of this Subsection, the…, and the plumbing itself must follow Part 7 (3.7.4.1.OBC Div. B 3.7.4.1. Plumbing and Drainage Systems(1) Except as provided in Sentence (3), each building situated on property that abuts on a street in which a public or municipal water main is located shall be provided with or have accessible to its occupants a plumbing system including a potable water supply, a sanitary drainage system and plumbing fixtures. (2)…).

Common mistakes

  1. Building area entered as gross area. Building area is one floor plate, gross area is all floors above grade.
  2. Wrong first storey. A walkout basement with a ceiling more than 1.8 m above grade can be the first storey, adding a storey to the building height.
  3. Forgetting the streets facing count. It can change which Part 3 article applies.
  4. One spatial separation line for the whole building. Each exposing building face gets its own row.
  5. Part 9 with a Part 3 room. An assembly room inside a Part 9 building still needs Part 3 for that room.

How to look it up yourself

Open Division A, Part 1 of the 2024 Compendium for the scope articles and defined terms, then Division B, Part 3 or Part 9. Search terms that appear in the code text:

  • "Application of Part 9" (Div. A 1.3.3.3.)
  • "Classification of Buildings" (3.1.2.1.)
  • "Streets" (3.2.2.10.)
  • "Occupant Load Determination" (3.1.17.1.)
  • "Limiting Distance and Area of Unprotected Openings" (3.2.3.1.)

Read the scope article in the code viewer alongside the classification article.

BCIN exam angle

Building classification, building area and spatial separation are core topics on the Small Buildings and Large Buildings exams, and the matrix is a good way to practise them together. Study the Small Buildings chapter on Part 3 classification, construction and building size or the Large Buildings chapter on classification, construction types and fire resistance, then try the free quiz on the Small Buildings exam or Large Buildings exam page.

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

© King's Printer for Ontario, 2024. Reproduced with permission.

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Frequently asked questions

What is an Ontario Building Code matrix?
It is a one-page table on the permit drawings that sums up the code analysis of a building: which Part of the code applies, the major occupancy, building area and height, the Part 3 or Part 9 classification, sprinklers, fire alarm, occupant load, barrier-free design, fire-resistance ratings and spatial separation. Each line points to the article it relies on, so the plans examiner can check the design quickly.
Is the code matrix required by the Ontario Building Code?
The Building Code itself does not print a matrix form. Municipalities ask for one as part of a complete permit application, and the common form used across Ontario was developed for architects and designers. Your building department tells you which form it accepts and when it is needed.
Does a Part 9 house need a code matrix?
Many building departments ask for a Part 9 matrix for larger Part 9 buildings, such as small commercial buildings, multi-unit residential buildings and some additions. A single house often only needs the information on the drawings. Check your municipality's permit checklist.
How do I know if my building is Part 3 or Part 9?
Part 9 applies to buildings of 3 storeys or less in building height, with a building area of not more than 600 m², used for residential (other than retirement homes), business and personal services, mercantile, or medium and low hazard industrial occupancies. Assembly, care, detention and high hazard industrial buildings, and anything larger, fall under Part 3 (Division A, Articles 1.3.3.2. and 1.3.3.3.).
What is the difference between building area and gross area on the matrix?
Building area is the greatest horizontal area of the building above grade, measured to the outside of the exterior walls. Gross area is the total area of all floors above grade. A two-storey building with 300 m² floors has a building area of 300 m² and a gross area of 600 m² (Division A, Article 1.4.1.2.).