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Ontario Building Code Part 9: What It Covers and How to Use It

Part 9 of the 2024 Ontario Building Code covers buildings up to 3 storeys and 600 m2. What it includes, how it is organized, and how to search it.
max building area for Part 9
600 m²
max building area for Part 9
max building height for Part 9
3 storeys
max building height for Part 9
sections in Part 9, with 9.36 reserved
41
sections in Part 9, with 9.36 reserved
building age at which Part 11 also applies
5 years
building age at which Part 11 also applies

Last updated

Part 9 of Division B, "Housing and Small Buildings," applies to buildings of 3 storeys or less 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 (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…). Bigger buildings, and assembly, care, detention and high-hazard industrial buildings of any size, fall under Parts 3, 4, 5 and 6 instead (OBC 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…).

Most houses, semis, townhouses, small apartment buildings, small shops and offices in Ontario are Part 9 buildings. It is also the core of the BCIN House and Small Buildings exams. This page explains what Part 9 covers, how its sections are organized, and how to find an answer quickly. Municipal building departments enforce the code and may set local permit requirements.

Part 9 at a glance

Item Detail Where
Name Housing and Small Buildings Division B, Part 9
Building height 3 storeys or less Div. A 1.3.3.3.(1)
Building area 600 m² or less Div. A 1.3.3.3.(1)
Occupancies Group C (not retirement homes), D, E, F2, F3 Div. A 1.3.3.3.(1)
Sections 9.1 to 9.41 (9.36 reserved) Division B
Structural design Part 9 tables, CWC guide, or Part 4 9.4.1.1.
Existing buildings (5 years or older) Part 11 also applies Div. A 1.3.3.3B.
Energy efficiency Part 12 and SB-12 12.2.1.2.

Our own summary of the scope articles.

How the code is put together

The 2024 Building Code has three Divisions:

  • Division A sets compliance, objectives and definitions. Words printed in italics in the code are defined in Article 1.4.1.2. of Division A, and the scope of each Part is in Subsection 1.3.3.
  • Division B holds the technical requirements, called acceptable solutions, in Parts 1 to 12. Part 9 is here.
  • Division C covers administration: permits, inspections, qualifications such as the BCIN system.

The Building Code Act, 1992 sits above all three and sets the permit requirement itself. The Compendium bundles the Act, the three Divisions, the Supplementary Standards (SA-1, SB-1 to SB-13) and the appendix notes.

"Building height" and "building area" are defined terms. Building area is the greatest horizontal area of the building above grade, measured to the outside of the exterior walls (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.). Exam questions often hinge on a building that is just over 600 m² or has a fourth storey.

The sections of Part 9

The 41 sections fall into a logical order, roughly the order you would build a house:

  • General and planning (9.1 to 9.11): general rules, definitions, materials, structural requirements, room sizes and ceiling heights (9.5), glass, windows and doors, stairs, ramps, handrails and guards (9.8), means of egress (9.9), fire protection (9.10) and sound transmission (9.11).
  • Below grade (9.12 to 9.18): excavation, dampproofing and soil gas, drainage, footings and foundations (9.15), floors-on-ground, columns and crawl spaces.
  • Structure and envelope (9.19 to 9.30): roof spaces, masonry, chimneys, fireplaces, wood-frame construction (9.23, home of the span tables), steel studs, heat transfer, air leakage and condensation control (9.25), roofing, cladding, stucco, interior finishes and flooring.
  • Services (9.31 to 9.34): plumbing facilities, ventilation (including CO alarms in 9.32), heating and air-conditioning, electrical facilities.
  • Special buildings (9.35 to 9.41): garages and carports, 9.36 reserved, cottages, log construction, park model trailers, reinforced concrete slabs, and change of use.

Things Part 9 sends you elsewhere for

Part 9 is not fully self-contained. Common jumps:

  • Structure beyond the tables. Members may follow Part 9, be designed to good engineering practice such as the CWC guide, or be designed to Part 4 (9.4.1.1.OBC Div. B 9.4.1.1. General(1) Subject to the application limitations defined elsewhere in this Part, structural members and their connections shall (a) conform to requirements provided elsewhere in this Part, (b) be designed according to good engineering practice such as provided in the CWC 2014, "Engineering Guide for Wood Frame…). Snow, wind and seismic data come from SB-1.
  • Firewalls follow Part 3 (9.10.11.3.OBC Div. B 9.10.11.3. Construction of Firewalls(1) Where firewalls are used, the requirements in Part 3 shall apply.).
  • Heating systems serving more than one dwelling unit generally follow Part 6 (9.33.1.1.OBC Div. B 9.33.1.1. Application(1) This Section applies to the design and installation of (a) heating systems, including requirements for combustion air, and air-conditioning systems serving only one dwelling unit, and (b) radiant heating systems in houses with a secondary suite including their common spaces. (2) The design and installation of…).
  • Energy efficiency is in Part 12 and SB-12, because Section 9.36 is reserved (12.2.1.2.OBC Div. B 12.2.1.2. Energy Efficiency Design(1) Reserved. (2) Except as provided in Sentence (3) and Sentence (4), the energy efficiency of all buildings shall (a) be designed to exceed by not less than 13% the energy efficiency levels required by Sentence 12.2.1.1.(2) of O. Reg. 332/12 (Building Code) as it read on December 31, 2024, or (b) conform to Division…).
  • Renovations of buildings at least five years old also fall under Part 11 (Div. A 1.3.3.3B.OBC Div. A 1.3.3.3B. Application of Part 11(1) Except as provided in Sentence (2), Part 11 of Division B applies to the design and construction of existing buildings, or parts of existing buildings, that have been in existence for at least five years. (2) If a building has been in existence for at least five years but includes an addition that has been in…), whose compliance alternatives can replace Part 9 requirements without proving impracticality (11.5.1.1.(2)OBC Div. B 11.5.1.1. Compliance Alternatives(1) A compliance alternative shown in Table 11.5.1.1.-A, 11.5.1.1.-B, 11.5.1.1.-C, 11.5.1.1.-D/E or 11.5.1.1.-F may be substituted for a requirement contained in Part 3, 4, 6 or 8 where the chief building official is satisfied that compliance with the requirement is impracticable because, (a) of structural or…).

How to search Part 9 fast

  1. Start with scope. Confirm it is a Part 9 building with Div. A 1.3.3.3.
  2. Go to the section, then the subsection. Learn the main numbers: 9.5 rooms, 9.8 stairs and guards, 9.9 egress, 9.10 fire, 9.15 foundations, 9.23 framing, 9.25 insulation and barriers, 9.32 ventilation.
  3. Search the article heading, not the question. Headings such as "Height of Guards" or "Separation of Residential Suites" are short and unique.
  4. Read every sentence of the article. Exceptions in later sentences, such as the rules for a house with a secondary suite, change the answer.
  5. Check the definition in Div. A 1.4.1.2. when a word is in italics.
  6. For tables, read the title and notes first so you know what the table is for.

Common mistakes

  1. Applying Part 9 to a building over 600 m² or over 3 storeys.
  2. Searching for 9.36 energy rules that Ontario does not use.
  3. Using notes written for the 2012 code. Numbering and values changed in 2024. See 2024 Ontario Building Code changes.
  4. Ignoring Part 11 when working on an existing house.

How to look it up yourself

Open the 2024 Compendium, Volume 1. Search Division A for "Application of Part 9" to confirm scope, then search Division B for "Housing and Small Buildings" to jump to Part 9. Many sections open with an application or general article, so read that first.

Part 9 is the heart of the House and Small Buildings exams. Start with the free study guide for the House exam or Small Buildings exam, then try the free practice quiz on each 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 buildings does Part 9 of the Ontario Building Code apply 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 (Division A, Article 1.3.3.3.).
What is Part 9 called?
Housing and Small Buildings. It is in Division B of the 2024 Building Code.
Is there an energy efficiency section in Ontario's Part 9?
Section 9.36 is reserved in the Ontario code. Energy efficiency for houses is in Part 12 of Division B and Supplementary Standard SB-12.
Where do I find the Ontario Building Code Part 9 for free?
The Ministry publishes the 2024 Building Code Compendium free on ontario.ca, and Publications Ontario offers free PDF volumes. Part 9 is in Volume 1 with the Act and Divisions A, B and C. The regulation on e-Laws, O. Reg. 163/24, is only a one-page adoption of the national code with Ontario amendments.
Does Part 9 apply to renovations of existing houses?
Part 9 applies to the work, but Part 11 (Renovation) also applies to existing buildings that have existed for at least five years and offers compliance alternatives (Division A, Article 1.3.3.3B. and Division B, Article 11.5.1.1.).