I used 1 1/2 sheets of foam insulation. My wall is 6' w x 8' h and two feet folds so it fits into a corner or free stands. I have used this method for about five years because it was so hard for me to get down on the floor to sandwich quilts. I have used spray baste exclusively all this time. No cover on the insulation so I can spray baste standing up. I just open the doors and windows when I spray and I don't spray all the way to the edge so I don't get the overspray. I don't have any problems with this method. Wouldn't do it any other way.