Klyde O'Scope
Chameleon Enthusiast
You're right—that's unusually wide for a single/double-hung.It's a hung window that's 60" along the sill (horizontal).

They usually max. out at 48" (which is why I asked). 60" high is not unusual.
Double Hung Window Sizes
Double hung windows are the most common type of replacement window in the United States. They come in a wide range of sizes to fit any rough opening. They are often found in the bedroom, kitchen, hallways, and all over the house. Double-hung window width can be anywhere from 24 to 48 inches. A double hung window’s height can range from 36 to 72 inches.
https://modernize.com/windows/standard-sizes
- Double Hung Width: 24″ min to 48″ max
- Double Hung Height: 36″ min to 72″ max
Here are a few solutions. I'm sure there are others.Actually the saga continues because my portable AC unit puts out air that smells very strongly, like chemicals. Might have an issue with its refrigerant? Upon further inspection the fins look all beat up and seems like Amazon might've sent me one that got returned by someone else. So gonna return that. I guess with a window unit we could figure out a solution for the insulation...like plywood and duct tape.![]()
https://upgradedhome.com/window-too-wide-for-air-conditioner/
https://www.google.com/search?client=firefox-b-1-d&q=window+too+wide+for+ac+unit
FWIW, I'm not a fan of using exposed fiberglass—rigid or batt—as some solutions suggest.
I've had personal experience with fiberglass dust making it into the room air—not healthy for lungs & other living things.
Rigid styrofoam (not U-foam with foil) insulation would be much better, IMO, filling any cracks with silicone caulk, and duct-taping if necessary. (Not a fan of U-foam either.)