What is the OBC requirement for window opening control devices in residential buildings?
Window Opening Control Devices in Residential Buildings: Ontario Building Code Requirements
Ontario's Building Code requires that openable windows in residential buildings be protected against child falls, either by a guard or by a Window Opening Control Device (WOCD) that limits the opening to no more than 100 mm (3 15/16").
The Core Requirement
Under the Ontario Building Code 2024, openable windows in buildings of residential occupancy must be protected by one of two means:
A guard installed at the window, or
A WOCD that limits the clear unobstructed opening to a maximum of 100 mm (3 15/16"), measured either vertically or horizontally [Source: Ontario Building Code 2024 — Volume 2, Page 199, Section 9.8.8.1.(4)].
The 100 mm (3 15/16") limit is recognized as the maximum opening size needed to prevent small children from falling through open windows [Source: Ontario Building Code 2024 — Volume 2, Page 199, Section A-9.8.8.1.(4)].
When Protection Is Not Required
Windows are exempt from this requirement where the bottom edge of the openable portion is located more than 900 mm (35 7/16") above the finished floor, or less than 1 800 mm (70 7/8") above the floor or ground on the exterior side of the window [Source: Ontario Building Code 2024 — Volume 2, Page 199, Section 9.8.8.1.(5)].
Acceptable WOCD Types and Important Limitations
Acceptable devices include fixed-stop levers, fixed-length cables, and fixed-position stop blocks. However, several window types and mechanisms are specifically flagged as non-compliant:
Rotary (crank) opening mechanisms cannot limit the opening to 100 mm, even with the crank handle removed.
Awning windows with scissor hardware may swing fully open once unlatched.
Sliding windows without built-in limiting devices are the most commonly affected window type.
The technical specification for WOCDs is found in ASTM F2090, "Standard Specification for Window Fall Prevention Devices With Emergency Escape (Egress) Release Mechanisms" [Source: Ontario Building Code 2024 — Volume 2, Page 199, Section A-9.8.8.1.(4)].
Provincial Comparison Note
Quebec and British Columbia carry essentially the same 100 mm (3 15/16") opening limit and the same 900 mm (35 7/16") / 1 800 mm (70 7/8") exemption thresholds [Source: Quebec Construction Code - 2020, Page 881, Section 9.8.8.1.(4) and (5)][Source: British Columbia Building Code - 2024, Page 980, Section 9.8.8.1.(4) and (5)]. Quebec adds a specific provision for windows that also serve as egress openings, requiring the WOCD to conform to ASTM F2090 and to be openable from inside without keys or tools [Source: Quebec Construction Code - 2020, Page 881, Section 9.8.8.1.(4)(b)].
Sources cited
OBC-2024-V2 • 2024 • p. 199 • §Section 9.8.8.1.(4)
OBC-2024-V2 • 2024 • p. 199 • §Section A-9.8.8.1.(4)
OBC-2024-V2 • 2024 • p. 199 • §Section 9.8.8.1.(5)
QBC • 2020 • p. 881 • §Section 9.8.8.1.(4) and (5)
BCBC • 2024 • p. 980 • §Section 9.8.8.1.(4) and (5)
This answer is AI-generated from the cited sources. While CodesWise grounds every response in the official code documents, you remain responsible for verifying the requirements that apply to your specific project. Always confirm against the authoritative code for your jurisdiction.