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Alberta issues code variance on window opening control devices

April 3, 2024  By Patrick Flannery

Allowable WOCDs restrict windows to opening 100 mm but can be disengaged "without tools or special knowledge" to allow opening up to 380 mm. Photo from Truth Hardware.

Alberta has issued STANDATA variance 23-BCV-001 amending its 2023 building code to recognize window opening control devices (WOCD) as an allowable way to meet both the requirements for egress from bedrooms and to prevent windows from opening far enough for children to fall out.

The variance reads: Required Guards
4) Except as provided in Sentence (5), openable windows in buildings of residential occupancy shall be protected by
a) a guard, or
b) a mechanism that can only be released with the use of tools or special knowledge to control the free swinging or sliding operation of the openable part of the window so as to limit any clear unobstructed opening to not more than 100 mm measured either vertically or horizontally.
(See Note A-

Allowable WOCD mechanisms are detailed in ASTM F2090 “Standard Specification for Window Fall Prevention Devices with Emergency Escape (Egress) Release Mechanisms.”


The variance resolves a long-standing conflict between fire-egress requirements that a bedroom window be openable to 380 mm and fall-protection requirements that restrict windows less than 900 mm off the floor from opening more than 100 mm.

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