Date of Publication: April 21, 2025 [2025.02.V-01.C]
Subject: Window Restrictors on Required Egress Windows and Windows Requiring Fall Protection.
2024 Ontario Building Code Reference(s):
Article 9.8.8.1. of Div. B.
Article 9.9.10.1 of Div. B.
Appendix note A-9.8.8.1.(4).
Incoming Request:
A house has been constructed with a bedroom window that provides the necessary clear opening to provide egress. However, the window is on the second storey of a house and the sill is less than 900 mm above the finished floor. Is a releasable Window Opening Control Device (WOCD) that complies with ASTM F2090, permitted as a means of both, protecting the window opening and allowing the window to serve as an egress window?
Executive Summary:
An ASTM F2090 compliant Window Operating Control Device (WOCD) installed on a required egress window that also requires fall protection is consistent with the intent of the OBC. Municipalities may choose to create a policy to ensure uniform enforcement.
Discussion & Considerations:
Sentence 9.9.10.1.(1) of the 2024 OBC states that a required egress window must be “openable from the inside without the use of tools” and “maintain the required opening...without the need for additional support”. There is no mention of “opening with not more than one releasing operation” or of “openable without specialized knowledge”.
Sentences 9.8.8.1.(4) and (5) of the 2024 OBC state that a window in a residential occupancy with its sill 900 mm or less above the finished floor must either have its opening limited to not more than 100 mm or be protected with a guard. Clause (4)(b) describes the means of limiting the opening as “a mechanism that can only be released by the use of tools or special knowledge…”. Appendix Note A-9.8.8.1.(4) states that the intent is to reduce the risk of small children being able to easily open the window beyond 100 mm, and then falling, and refers to ASTM F2090, “Standard Specification for Window Fall Prevention Devices With Emergency Escape (Egress) Release Mechanisms”, for a technical description of WOCDs.
Wording within ASTM F2090 describes compliant devices as being designed to be released (for emergency escape) “without ...special knowledge.” While this statement may be contradictory to Clause (4)(b), the standard describes compliant devices as being designed to “protect against inadvertent opening of the window sash beyond the controlled open position by a young child” which is consistent with the intent stated in Appendix Note A-9.8.8.1.(4) of the 2024 OBC.
The language between the ASTM F2090 and the 2024 OBC is not entirely aligned, but the intent of both documents is to prevent a small child from opening the window beyond the 100 mm limit and falling out, while still allowing the window to be opened (without tools) to its full extent for egress. It should be noted that the standard is not referred to in the body of the Code, and is therefore not referenced in Table 1.3.1.2. of Div. B.
Risk/Benefit Analysis:
Egress requirement:
For egress windows in compliance with Sentence 9.9.9.10.(1), an ASTM F2090 compliant WOCD would not appear to contravene the minimum stated requirements.
It should be noted that the 2020 NBC requires that an egress window be openable without the use of “keys, tools or special knowledge”, and Appendix note A-9.9.10.1.(1) states that “The minimum unobstructed opening specified for escape windows must be achievable using only the normal window operating procedure.” However, the OBC does not contain this language in the corresponding Appendix Note.
Fall protection requirement:
Clause 9.8.8.1.(4)(b) of the 2024 OBC requires opening protection on a window to only be releasable “with the use of tools or special knowledge”, to prevent a small child from opening the window beyond 100 mm and falling out the window. A releasable mechanism (WOCD) conforming to ASTM F2090 would appear to meet this requirement.
As background, the most recent version of ICC’s International Residential Code, which forms the basis for many U.S. Building Codes accepts ASTM F2090 WOCD’s on windows that require both fall protection and egress. Alberta Municipal Affairs published STANDATA variance 23-BCV-001 which permits (with some restrictions) the use of ASTM F2090 WOCD’s on egress windows requiring fall protection. In British Columbia, a 2024 Building Code Appeals Board decision 1940 found that an ASTM F2090 WOCD could satisfy the requirement for fall protection, but not egress, since the full egress opening cannot be achieved by normal window operating procedure. Code change requests have been submitted to the NBC for inclusion of the ASTM F2090 as a referenced standard, for use on egress windows and openable windows needing protection. A technical bulletin describing ASTM F2090 WOCD’s can be found here.
Final Recommendation:
The presence of an ASTM F2090 WOCD does not contravene the requirements of Sentence 9.9.9.10.(1) for an egress window. An ASTM F2090 WOCD also meets the intent of Clause 9.8.8.1.(4). Generally, required egress windows with sill heights lower than 900 mm can and should be avoided. However, if a designer is proposing an egress window with an ASTM F2090 WOCD, they must satisfy the AHJ that their design provides an equal or greater level safety than that required by the code, either by a detailed report, an Alternate Solution Proposal, or through an established municipal policy.
Recommendation to Ministry of Municipal Affairs and Housing:
Provide comment on whether or not an ASTM F2090 WOCD–equipped window can serve as both an egress window, and be considered to be protected as per 9.8.8.1.
Referenced Documents:
- 2024 Ontario Building Code: O.Reg. 163/24 amended to O.Reg. 5/24
- Alberta Municipal Affairs’ STANDATA variance 23-BCV-001
- British Columbia’s Building Code Appeals Board decision 1940
- A Joint Fenestration and Glazing Industry Alliance (FGIA) and Window and Door Manufacturers Association (WDMA) Technical Bulletin: Understanding Window Opening Control Devices (WOCDs)
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.