Date of Publication: April 24, 2025 [2025.04.V-01.C]
Subject: Minimum Area of Combined Spaces
Ontario Building Code Reference(s):
2012 OBC:
Sentences 9.5.8.1.(1) and 9.5.1.5.(1) of Div. B
Article 9.5.10.1. of Div B
2024 OBC:
Sentences 9.5.3E.1.(1) and 9.5.1.3.(1) of Div. B
Article 9.5.4.1.of Div. B
Incoming Request:
An application has been received that shows a studio apartment with living, dining, bedroom and kitchen combined in one space. The minimum combined area of 13.5 m2 [specified in 9.5.8.1.(1) of the 2012 Code and 9.5.3E.1.(1) in the 2024 OBC, can only be achieved by inclusion of the area of the hallway from the entrance door to the living space. Can the hallway be included in the minimum area of the combined space? See sketch below for reference.
Executive Summary:
Minimum areas of combined spaces must consist only of the specified areas. Hallways or other spaces do not contribute to the minimum area.
Discussion & Considerations:
The wording of Sentences 9.5.8.1.(1) of the 2012 code and 9.5.3E.1.(1) in the 2024 OBC, state that “…where living, dining, bedroom and kitchen spaces are combined…the area of the combined spaces shall be not less than 13.5 m2.” The Code does not speak to total area of the suite or inclusion of other rooms or spaces. Furthermore, Sentence 9.5.1.3.(1) of the 2012 Code and 9.5.1.1A.(1) of the 2024 OBC states that “Minimum floor areas specified in this Section do not include closets or built-in bedroom cabinets” which gives an indication that actual habitable/usable area is the main consideration in calculating room sizes.
However, Sentence 9.5.1.5.(1) of the 2012 Code and 9.5.1.3.(1) of the 2024 OBC, state that rooms are “...permitted to be less than required..” if “...it can be shown that the rooms and spaces are adequate for their intended use, such as by the provision of built-in furniture”.
It should be noted that the objectives and functional statements for room dimensions are related to facilitating timely egress. Therefore the layout of the space with typical furnishings (built-in or not) must leave enough room for egress.
Risk/Benefit Analysis:
As stated above, the prescribed minimum sizes assume typical furnishings and are designed to ensure occupants are not impeded in egress. Designers are permitted to propose smaller spaces, but must indicate how the intended function is being achieved. If built-in furniture is proposed, the submitted plans must indicate what built-in furniture is being provided, its location, size and function. It must also be shown that egress can still be provided when the furniture is in use, especially for fold-down or convertible furnishings such as beds, dining tables or desks. As reference, one might look to the minimum hallway widths of Article 9.5.10.1. in the 2012 code and 9.5.4.1. in the 2024 OBC.
Final Recommendation:
When calculating minimum areas of combined spaces only the combined spaces specified can be used to calculate the minimum area. Hallways or closets may not contribute to the minimum area. Lesser areas are permitted only where the design of the rooms is demonstrated “to be adequate for their intended use” and egress can be maintained.
Recommendation to Ministry of Municipal Affairs and Housing:
None at this time.
Referenced Documents:
2012 Ontario Building Code:
- O.Reg. 332/12 amended to O.Reg.451/22
2024 Ontario Building Code:
- 2024 OBC O.Reg. 163/24 Amended to 5/25
Disclaimer:
This guidance document is intended to assist building officials by gathering relevant information to interpret the OBC Act and the prescriptive requirements of the Ontario Building Code, and is intended to be a best practice aid for building officials.
The views expressed within this guidance document should not be considered as the official interpretation of legislated requirements based on the Ontario Building Code, as the final responsibility for interpretation rests with the local Authority Having Jurisdiction.
The views of this advisory committee should not be construed as legal advice.