Thank you all, yea i looked and called Home Depot, but they said all they have is 8' and dont know where i could get it.
There is a fiberglass on the bottom and i was able to take that off and can reuse it, and there is a top, it looks like the top piece had wall paper on it where the bunk slides out. but the whole thing is 3/4" thick. But i will look for the fiberglass on plywood & maybe that's what was on it and it just came apart from being wet. Most of it just fell apart when i was taking it out.
I do have one more thing to ask, on the out side walls, it is pull away from the wood, but there is a few places that will not come lose. I was able to get some of it away but i need to get more of it pulled back so i can replace the wood, is there something that will losing the glue on it? Can the fiberglass be glued back down? my roof has a lot of spots that are lose but not leaking that i can tell.