Nesting Casement Window Handles
Overtightening the operating handle won't create a tighter seal and could lead to water infiltration.
I just replaced a bunch of casement windows, and the homeowner decided to help me install the crank handles. After he shut and latched a window, I noticed that he would give the handle an extra crank before pulling it off and rotating it into the position where it would seat down in its holder. He told me he wanted his windows to be sealed very tight. I recall hearing that overtightening a casement window is a mistake, but he wouldn’t hear of it. Which of us is right, or does it even matter?
—Jerome Buckley via email
Eric Klein, installation and service instructor specialist at Marvin, replies: It does matter—quite a bit, in fact. Here’s the proper way to “nest” an operating handle on a casement window: First, crank the window shut so that the sash comes in contact with the weatherstripping on the window frame. Pull the lock handle down so that it draws the sash tightly to the frame. Then pull the operating handle off the operator shaft and position it so that it will nest down into the operator cover without any additional shaft rotations. That’s it.
The operator handle and operator arm on a casement window are designed to do just that—operate the window. They are not designed to seal the sash in place. Sealing a window is the job of the bezel locks on the frame working in conjunction with the keeper latches on the sash. Not only will cranking too hard on an operating handle not improve performance, it will likely diminish it. In the worst-case scenario, overtightening could lead to water infiltration.
On most casement windows, the operating hardware is only secured to the bottom of the window sash. When the operating arm pulls too hard on the bottom rail of the sash, it often causes the top of the sash to be pulled away from the frame, creating a gap. When it comes to windows, gaps are bad. When you tell your customer that he was wrong, you can break it to him gently by letting him know that he’s not alone; casement-window failure due to overtightening is a common cause of callbacks.
From Fine Homebuilding #312