I spent several hours in a rabbit hole here this morning and I’m in need of some help. I have a control room that is 13’ wide 18’ long and 12’ high. Along the very back wall I would like to built a 12” deep 10ft tall bass trap. From my reading today it seems if I am building something that deep, that I can just use pink fluffy insulation. At that depth should I still space it from the wall some? My problem is I’m not clear which version I should use and I’m not clear how to stack/fill it properly. Do I hang the insulation vertically (w paper backing?) or should I lay it one on top of the other horizontally? I am not clear which insulation I can even use or if it should have paper backing or not. I am ten minutes from Home Depot so if anyone could tell me which insulation to use that they carry, that would be great.

It's important to work from a good design, so that you can maximize performance within whatever limitations we're working with (usually budget, or how much space inside the room we can use). There's not one simple answer. If you aren't sure which insulation to use I'd consider getting some help with the treatment strategy/design you have planned to bring things into focus for you.

owens corning r-13 will be good for what you're planning. you don't want facing. hanging it would probably be annoying at that depth. you can stack it but if you stack too many layers on top of each other it will compress and be less effective. i have done what you are describing and the way i did it was by attaching shelves to my wall at 2' intervals, then stacking the insulation on each shelf. after you've made the trap, you're going to want to cover it in fabric. i suspended a curtain from my ceiling, but you could also build a frame and staple the fabric to it. i used a layer of cotton and a layer of cotton batting to make sure no fibers would escape.

some good inspiration here, look for the albums that show the studio construction process: https://www.facebook.com/MyRoom.Acoustics/photos_albums