Installing window ACs year after year without trashing my sashes

May 22, 2020 7:31 AM

What is the recommended way to secure window air conditioners that are installed and removed each year? I need to keep the sashes in place to prevent the AC from falling out of the window onto the ground below. But using l-brackets and wood-screws year after year feels like I'm damaging my sashes.

BobVilla.com recommends using small L-Brackets to fix the two sashes in position after you've installed the AC. This keeps the sashes from moving, and keeps the AC in place. Got it, I understand, and I've done that. The problem is that I don't like using wood screws every year to attach the L-Brackets. It feels like I'm trashing the wood and that eventually it won't work.

I thought of permanently mounting threaded inserts in the sashes, which would in theory let me use machine screws to attach the L-Brackets. I've never used threaded inserts, though, and with social distancing I'm not keen to shop for them in person. Do they come in a small enough size for this use? I'd appreciate any reaction to using threaded inserts. If you think it's a good idea, how should I go about finding the right size, mounting them, etc?

Is there some other approach I'm thinking of that will let me secure my sashes and my ACs that I can do year after year without damage? Lots of people use window air conditioners. There's got to be a good standard way of doing this.

posted by Winnie the Proust to Home & Garden (8 answers total)

What I did was take a 1x4 and cut it to the width of my window, and put it in the little slot that the window rides in, above the AC and close the sash down onto it. Then screw the AC to the board.

To keep the sash from being lifted up and accessed that way, I also cut a board and installed it vertically to push the window down.
posted by Huffy Puffy at 7:50 AM on May 22, 2020 [2 favorites]

Since you mention the AC falling onto the ground below, I take it that you're not on the ground floor? The obvious solution that comes to mind is leaving the AC in place and just wrapping it up in a cover during the seasons you don't use it, but obviously that's easier said than done for the second floor and up.
posted by tobascodagama at 8:10 AM on May 22, 2020

The Wirecutter recommends the Top Shelf TSB-2438 Window Air Conditioner Mounting Support Bracket. They say: This expensive but foolproof bracket requires no drilling and can be assembled in less than five minutes.
posted by ShooBoo at 9:57 AM on May 22, 2020 [2 favorites]

Seconding the bracket ShooBoo mentions above - that's what I use. The bit on the right in that picture sits inside the window track, or hooks over it, and the bracket bit rests against the building wall. It assembles really quickly, and does not need any tools or screws or anything like that (the brackets slide in and out of the platform, and there are springloaded posts that latch into holes on the platform to adjust how long the brackets need to be).

The most complicated bit was trying to adjust it so that it sat level - when I first set it up it was sloped down towards the sidewalk, and it was a little counter-intuitive trying to align everything properly and adjusting all the various bits was a little tricky to do on my own. (Not because it was heavy or complicated, just because it was a two-handed operation and I needed my roommate to hold it steady while I worked.) But once I got it level I just plopped the AC onto it and was good to go. It was also just as easy to pack it away in the fall (lift off AC, lift bracket out of window); I was even able to dis-assemble the bracket by retracting the springloaded posts and pulling them back out of the platform.
posted by EmpressCallipygos at 11:07 AM on May 22, 2020

Threaded inserts work really well, better than an equivalent sized wood screw. Something like these 10/24 brass inserts would work well in your application.

To secure the window in the partially open position I'd install a brass slide bolt. There are an endless variety of styles and finishes to choose from. If you are really handy you can even use a recessed version. You want one that is actually brass and not brass plated for durability and so it won't rust.
posted by Mitheral at 12:08 PM on May 22, 2020 [2 favorites]

Here's what I do: I've cut two pieces of 1x2 to the distance between the top of the lower sash and the top window frame with the air conditioner installed. Then, I wedge these pieces between the top of the lower sash and the top of the frame (one on the left side, one on the right side). I use strong velcro to hold them in place, but this is just so they don't fall over; it's the wedged 1x2s that are holding the window closed.

This is, undoubtedly, less safe than any of the methods mentioned here, but it's safe enough for me. I would definitely think differently if I lived in a place where people ever walk under my air conditioners, but the only thing that will happen if my air conditioner falls out the window is that it will break the air conditioner (and maybe flatten a few shrubs). There has never been a time where I've felt unsafe about doing this, even though I realize it's not the standard "safe" way.
posted by Betelgeuse at 2:00 PM on May 22, 2020 [2 favorites]

Threaded inserts sounds like a great solution to this problem to me, and I might actually steal this idea. If your local social distancing requirements mean you can't or prefer not to shop for them in person, but you're comfortable with ordering them online, there's a wide variety at McMaster-Carr. Their chart lets you pick the machine threading you want/need, and also tells you the size pilot hole you need to drill for the insert. They've got plenty more options as well if the brass screw-in style I linked isn't to your liking.
posted by biogeo at 10:46 PM on May 22, 2020 [1 favorite]

Response by poster: Thanks for all the suggestions. With this feedback I've ordered some 10-24 threaded inserts from McMaster-Carr and we'll see how it goes. If they don't arrive by installation time, I'll use some 1x4's to keep the top sash pushed down onto the window as a couple of you have suggested.

I'll report back.
posted by Winnie the Proust at 8:55 AM on May 24, 2020 [2 favorites]