a/c sealing question

ok, i want to put a window a/c in my bedroom. Problem is that my window is a horizontal sliding one and the cheaper (under $200) are made for vertical windows. What sort of insulating material can i use for the space between the top of the a/c and the top of the window? how do i do it? i'm pretty good at building shit and i have a decent amount of tools and access to power tools.

a website that someone knows would be AWESOME.

ok, i want to put a window a/c in my bedroom. Problem is that my window is a horizontal sliding one and the cheaper (under $200) are made for vertical windows. What sort of insulating material can i use for the space between the top of the a/c and the top of the window? how do i do it? i'm pretty good at building shit and i have a decent amount of tools and access to power tools.

a website that someone knows would be AWESOME.

If you go to homedepot, they usually have a certain type of insulating foam that's easy to cut and shape etc. It came with the portable air conditioner I put in my dorm earlier this year.

If you're not worried about how it looks, cut a sheet of plywood to fit; not only will you have a custom fit, but wood also insulates.

I was presented with the same problem in my house when I wanted to add an air conditioner because most of the windows on my main level are "sliders". I ended up having to go to Sears to get an air conditioner that would work in my window,( cost $449 for a 12,000 btu unit 4 years ago.:eek: ) When I installed it in my window I ended up with a space about the same size as the a/c unit's height above the unit itself. I ended up taking a piece of plexiglass and putting a metal frame around it and installing it above the unit to take up the space that was left over. If you don't have as much space as I did, you could use insulating foam board, (I've seen it in blue,green,or pink colors,) that would do a good job of filling in the space while insulating the cool air from your a/c from the warm outside air. I also ended up buying long sections of foam sections that were 1"x1", and 2"x2" and about 2 to 3 ft. long and cutting them to fit in any cracks or open area around the a/c unit.They "smush" down very well to fit in the open area, then expand, sealing the area.