You can start by grabbing some expanded owens-corning pink foam boards. They come in 2" thick and are easily cut. Also get a can of the water-based spray foam, so that you can clean it up easily in the future if you need to.
Cut 2 pieces from the foam board to fit the hole and so you end up with 4" of insulation. Fill any gaps around the edges with the spray foam, and enjoy the lack of cold air making it into your living space.
dablakh0l t1_j22cw4o wrote
Reply to Help filling in Air Conditioning Hole in my Room. by Crudeyakuza
You can start by grabbing some expanded owens-corning pink foam boards. They come in 2" thick and are easily cut. Also get a can of the water-based spray foam, so that you can clean it up easily in the future if you need to. Cut 2 pieces from the foam board to fit the hole and so you end up with 4" of insulation. Fill any gaps around the edges with the spray foam, and enjoy the lack of cold air making it into your living space.