Window fall protection achieved by pesky window locks

Minnesota adopted a new state building code in January of 2015, and with that came numerous changes.  I blogged about the new Minnesota building code last January, but one important change that I never mentioned was the addition of window fall protection, located under section R312.2.  Here’s the exact text from the Minnesota State Building Code, which comes directly from the 2012 IRC (which we adopted in 2015):

R312.2 Window fall protection. 
Window fall protection shall be provided in accordance with Sections R312.2.1 and R312.2.2.

R312.2.1 Window sills.
In dwelling units, where the lowest part of the opening of an operable window is located more than 72 inches (1829 mm) above the finished grade or surface below, the lowest part of the window opening shall be a minimum of 36 inches (914 mm) above the finished floor of the room in which the window is located. Operable sections of windows shall not permit openings that allow passage of a 4-inch diameter (102 mm) sphere where such openings are located within 36 inches (914 mm) of the finished floor.


1. Windows with openings that will not allow a 4-inch diameter (102 mm) sphere to pass through the opening when the window is in its largest opened position.

2. Openings that are provided with window fall prevention devices that comply with ASTM F 2090.

3. Windows that are provided with window opening control devices that comply with Section R312.2.2.

4. Replacement windows.

R312.2.2 Window opening control devices. 
Window opening control devices shall comply with ASTM F 2090. The window opening control device, after operation to release the control device allowing the window to fully open, shall not reduce the minimum net clear opening area of the window unit to less than the area required by Section R310.1.1.

In short, double and single hung windows located within 36 inches of the floor and having an outside drop-off of more than 72 inches need safety devices that prevent the windows from fully opening.  Specifically, the window can’t open enough to allow the passage of a 4” sphere.  I’m sure there are several different types of safety devices available, but the only ones that I’ve seen so far have been sash stops that look just like regular sash stops.  The main difference is that they stay in the open / locked position until manually closed.  After they’re manually closed, you get to open and close the window once.  After that, they automatically return to the open / locked position.  The video clip below shows a demonstration.

For information about the reasoning behind this new requirement, click here: child window safety.  I feel the same way about this new requirement as I do about plastic outlet plugs: they’re super annoying, but nobody wants kids getting hurt or killed.

Author: Reuben SaltzmanStructure Tech Home Inspections

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Reuben is a second-generation home inspector with a passion for his work. He grew up remodeling homes and learning about carpentry since he was old enough to hold a hammer. Reuben grew up thinking he was going to be a school teacher because he enjoyed teaching others so much. In a sense, that’s a lot of what home inspections are about, so Reuben truly does what he loves. Sharlene has worked with Structure Tech since 2000 and Reuben has been contributing to her blog since 2008.

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