Check with AHJ before designing upstairs windows: OBOA.
June 14, 2025
Check with AHJ before designing upstairs windows: OBOA
By Patrick Flannery
The Ontario Building Officials Association has issued guidance on upstairs bedroom windows that simultaneously require egress for fire safety and limited opening to prevent child falls. The two parts of the National Building Code (and therefore most provincial codes) are presently contradictory, since one part says the window must open 380 millimeters to allow egress, and another part says the window must not open more that 100 millimeters to protect children. There are window opening control devices that limit opening but can be released in the event of fire. These have been allowed in Alberta, but the language around them remains confusing in other jurisdictions because the egress and fall-safety requirements again conflict over whether the limiter should be able to be released using “tools or special knowledge” or not.
The OBOA points out that all of this can be avoided by providing an egress window in upstairs bedrooms that does not have a sill lower than 900 millimeters above the floor. The difficulty only emerges when the design calls for an operable window with a sill lower than 900 mm in an upstairs area requiring egress and there is no other egress window in the room. If the design does call for this, the OBOA says it is up to the Authority Having Jurisdiction to decide whether the situation is safe. So best to check first.
