I am moving into an apartment, and I have a cat. I need to alter the windows in a way so that it can’t be opened beyond a couple of inches - little enough that there’s no chance of that cat slipping out. Here are the catches:

  • We can’t alter/damage the window frame in any way; we have to be able to leave it just as we found it. No screwing into the frame.
  • We’d rather not install screens, as we really love the view.
  • We’re hoping for something that can be done with easily accessible hardware, since we’ll be stuck with the windows closed until we figure this out.

I imagine two strategies: a cord/chain of some sort that limits how far open the window can go, or something to jam into the hinge so that it stops earlier than at it’s built-in bump. But I am open to other options!

This is my first time trying to do something like this, and I’m not sure who I could ask about this other than the internet. Thanks in advance.

Any thoughts or ideas could help!

enter image description here

enter image description here

  • Must be a smart cat that can open a window farther than what you have opened it to. – Alaska Man Apr 14 '20 at 21:34
  • Be careful where a small child can move a chair over to a window and “push a screen out”. The Code requires the opening to be less than 4” where a child can fall through. – Lee Sam Apr 15 '20 at 1:29

It appears that the regulation for the angle of the window is the distance between the mounting screws for the rails in which the brace slides.

The ideal work-around would entail removing the bottom screw from each side and inserting a metal shim that fits within the track below the slider. Return the screw and the slider cannot drop far enough to open the window to cat-head-width. CAUTION: cats can pass through holes far smaller than you might think!

One aspect of this method is that the sliding mechanism, including the rail, has to be accessible when the window is closed to the maximum desired opening.

But wait, there's a work-around to that as well.

The shim that would have been inserted between the bottom screw and the slider now has a slot to allow it to pass around the bottom screw. It is of sufficient length to reach to the bottom of the window frame and can be slipped into place even if the window opens only a few inches.

window shim

Depending on the width of the pivot assembly, one may be able to purchase a piece of aluminum or steel of sufficient width to work in this manner. The Home Depot has a materials section with solid aluminum rod and flat as well as solid steel rod and flat. Aluminum is easier to work and should hold up well enough if one does not slam things together.

You'd need a piece thin enough to slip under the inward facing lips with sufficient width to engage as much of the lip area as possible. Even if the thinnest piece you find is too thick, you could file or sand away material to get it to fit in place.

thin or thick metal flat

In the image above, the top represents the view from above if the flat aluminum is thin enough to fit in the groove/lips. The bottom is the answer if the piece is too thick, and has the corners filed/sanded away to provide placement.

All of this should work with the recently revealed "bumps" that provide limitation of travel of the sliding mechanism. The bumps are going to pose a problem with placing a single spacer above the screw, but the single spacer above the screw can be of the right hand side of my original drawing with a hole for the screw to engage.

screw hole in spacer

  • Great answer... I'd just mention that the shim has to be of sufficient length to hit the bottom of the frame. – Aloysius Defenestrate Apr 14 '20 at 22:20
  • This is just the kind of answer I was hoping for - it really seems like you know what you’re talking about! But I am still not totally clear - is a “metal shim” something I could buy at a hardware store? Presumably I’d have to measure something first? Any more details would be great. – liam Apr 15 '20 at 0:20
  • Oh, and I would also say that there are two metal bumps that appear to actually stop the window, which are visible in the photo and they are between the two screws. – liam Apr 15 '20 at 0:21
  • I've added a few edits to address your commented questions. – fred_dot_u Apr 15 '20 at 0:39

You could go with an

adjustable window screen,

One that is just tall enough to discourage your smart cat but not so big it blocks the entire window and your view.

It slides to adjust to the width of your opening, you could put it up when needed and take it down when not needed.

If it does not fit exactly or does not stay in place then You can make some modifications and learn to love your adjustable window screen.

enter image description here

  • The window in your photo opens vertically, while the window in the OP is a tilt-out version and won't take this design of screen. – fred_dot_u Apr 14 '20 at 21:59
  • @fred_dot_u - Yes, the photo was just to show the screen. It would still fit between the window rails and be enough of a deterrent for the cat. ( not flies or mosquitoes ) It could be enough if the window is not opened fully. No unauthorized mechanical alterations to the window mechanism needed. – Alaska Man Apr 14 '20 at 22:08
  • I see that now. By having the spread-open type, it brings the opening to zero and places it higher up as well. Much simpler than my answer, unless the cat is really smart. – fred_dot_u Apr 14 '20 at 22:13

If you're lazy like me fit a regular security chain,

enter image description here

or maybe you can jam that track using a coin.

  • Think I could attach one of these with some 3M strips? Can’t damage the frame at all. – liam Apr 15 '20 at 14:48
  • that's probably not going to work – Jasen Apr 16 '20 at 5:17
  • What would go wrong you think? Metal not sticking to the 3M strips? Any other non-damaging ideas to hook one of these on? – liam Apr 16 '20 at 20:05
  • it peeling off starting at one end of the strip – Jasen Apr 16 '20 at 20:06
  • it's propbably easier to tie a string to the handle and anchor the other end to the striker or to a 3m hook. – Jasen Apr 16 '20 at 20:08

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