Date of Publication: June 8, 2026  [2023.23.V-02.C]

Subject: Exterior egress dimensions for an individual dwelling unit. 2024 OBC UPDATE

2024 Ontario Building Code [O.Reg. 163/24 Amended to 5/25] Reference(s):

Subsections 9.9.3., 9.9.5.,9.9.6., and 9.9.9. of Div.B.

Sentence 9.5.5.(1) of Div.B.

Article 9.9.2.1. of Div.B.

Summary of Changes: Updated references, editorial changes.

Incoming Request: 

A secondary suite has been constructed in a house. The only access to and from the secondary suite is via a sliding door at grade to the rear yard, and then through a side yard walkway to the front yard and sidewalk. The side yard setback is 1.2 metres, but there is a gas meter and an air conditioner condenser unit in the side yard, effectively reducing the egress width to 750 mm and 300 mm respectively. There is also a fence and heavy shrubbery reducing the width to approximately 850 mm in places. 

What is the minimum clear dimension for a means of egress in this situation?

Executive Summary:

The OBC does not regulate minimum dimensions of a means of egress serving an individual dwelling unit or a house. Municipalities may want to consider policies or by-laws to ensure safe access and egress is provided, particularly when a secondary suite is accessed by a rear or side yard.

Considerations:

First consider the definition of means of egress (MOE): In relation to an individual dwelling unit, it includes both exits and access to exits in a continuous path from any point in the dwelling unit to an open public thoroughfare or an exterior space, protected from fire exposure, which has access to an open public thoroughfare. In our example, we will assume that the only access to an open public thoroughfare is via the side yard in question, therefore this exterior side yard will form part of the means of egress. Whether it is the access to exit or the exit is debatable. 

Subsections 9.9.3. (Dimensions of Means of Egress) exempts individual dwelling units and houses with secondary suites from the requirements, while 9.9.5. (Obstructions and Hazards in a Means of Egress) exempt only MOE’s within or serving a single dwelling unit. Article 9.9.2.4. (Principal Entrances) also contains an exemption for individual dwelling units and houses with a secondary suite. Neither Subsection 9.9.6. (Doors in a Means of Egress) nor 9.9.9. (Egress from Dwelling Unit) offer any dimensional requirements. 

Sentence 9.5.5.(1), however, does speak to minimum door size for a principal entrance to a dwelling unit, or a house with a secondary suite, specifically 810 mm wide by 1980 mm high. The OBC appears to be silent on any further dimensional requirements for a means of egress from an individual dwelling unit. This may have made sense when the majority of houses in Ontario consisted of one dwelling unit with a front door to the street. However housing has changed, secondary (and tertiary) suites are being encouraged, and not all dwelling units or houses have an exterior door that discharges directly to a front yard with direct access to a public thoroughfare. 

For reference, Codes in some jurisdictions regulate a means of egress having three parts, access to exit, exit, and exit discharge, with the latter being the portion between the building and the public thoroughfare or designated point of safety. 

Risk/Benefit Analysis:

Timely and safe egress from a building and reducing the likelihood of injury to persons are among the most basic functions and objectives of the OBC (OS3.1, OS3.7, F10, F30). The situation described above has the potential to delay egress, cause injuries to persons unfamiliar with the property, and slow or impede any emergency responders. This is further reinforced by Sentence 9.10.20.3.(2) which generally states that where firefighting access to a building is required, it must take into account practicalities such as weight of firefighting equipment, overhead clearance, and, it could be argued, width of access for firefighters. However, as shown above, there does not appear to be a Code provision that prescribes a minimum width for this part of the means of egress. As such, municipalities may choose to develop a policy to ensure minimum requirements for all portions of an exterior means of egress from a dwelling unit, be it a secondary suite or principal dwelling unit.

The following steps may be helpful:

• Consultation between building, zoning and with emergency services departments to establish a minimum acceptable width.
• Consult with planning and zoning staff to identify potential conflicts between permitted side-yard setbacks and permitted secondary suites.
• Develop a by-law for two-unit dwellings which prescribes minimum unobstructed dimensions, maximum slopes, and surfacing requirements for egress paths from dwelling units.
• Consider including provisions for future secondary suite entrances in zoning provisions for new housing. 
• Require all building permit applications for secondary suites to include a detailed site plan showing dimensioned egress paths and noting any obstructions, including overhead clearance, utilities and parking spaces for occupants.
• Note that if a third dwelling unit is provided in the building or elsewhere on the property, or if more than one dwelling unit shares a means of egress many of the general egress and exiting requirements of Section 9.9. may be applicable. 

Final Recommendation(s):

The OBC does not appear to prescribe a minimum clear width or height for exterior portions of an exit or means of egress serving a single dwelling unit. Municipalities may consider developing bylaws or other policies to ensure functional, safe and unobstructed means of egress are provided to secondary suites, which are often accessed through rear or side yards.

Recommendation to the Ministry of Municipal Affairs and Housing:

Provide an appendix note or expand Subsection 9.9.9. to include a specific provision setting out minimum required dimensions applicable to interior and exterior means of egress serving an individual dwelling unit. This will assist AHJ’s in ensuring safe egress and access is provided to all dwelling units including secondary suites accessed through rear and side yards.

Referenced Documents:

2024 Ontario Building Code [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.