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Ordering windows recently, I was alerted by my supplier to Window Opening Control Devices, WOCDs. A WOCD is a mechanism that restricts a window opening to less than 4". The intent is to afford fall protection. If the base of your window sill is 6' or more above grade, building code requires a minimum sill height of 24". That requirement is for residential construction of three stories or fewer. Don’t have the minimum sill height? Then a WOCD is required.

Window opening control devices have been code required since 2018. The heads-up from my supplier was that local code enforcement officers were starting to enforce it. In addition to limiting a window opening to 4" or less, the WOCD must be easily releasable, allowing the window to fully open. Easily releasable is defined as needing 15 pounds of force or less.

I ordered windows with WOCDs for all the second-floor and attic windows on my current restoration. These limiting devices are relatively new and window manufacturers seem to be struggling with how to implement them. The windows I’m installing are double-hung; the sash slides up and down on a track in a frame. The windows I purchased have just transitioned from a sash limiter built right into the sash to one mounted in the track. The limiters project into the path of the sash, stopping the sash from fully opening. To fully open the sash you push in the tabs of the limiter. Next time the sash is closed, the limiters automatically reset to their limiting position.

There are 22 windows in my current project. Of those, I ordered 15 equipped with WOCDs. I’ve put in five of the windows lacking WOCDs, four with. The windows are large, heavy, expensive, and breakable. As a solo builder, I remove the sash prior to installation and temporarily install the frame. Next, the sashes go back in the frame and are locked in place. With the sash in, I complete the window installation. It’s a technique I’ve had good luck with.

From my limited experience installing and operating windows equipped with WOCDs, here’s what I’ve learned: The WOCD needs to be in contact with the sash, even when depressed to allow full operation. This means that it’s in the way when you remove the sash. I broke the first set of sash limiters removing the sash prior to installation. You can still remove the sash, but you have to do it below the WOCD. First lesson learned. I broke my second set of sash limiters when I forgot to depress them before opening the window fully. It doesn’t take much force to shear them off. I can easily see every sash limiter meeting a similar fate. I’m all for keeping toddlers safe from falls through windows, but I don’t think the devices, at least not the ones I’m using, are up to the task — the task being a window safety mechanism that is long lasting, effective, and easy to live with. A difficult goal to achieve.