Im building a shop with a grade beam and plies, so I dont need anything under the pad for support, my question is if I was to use a 3" void form and 3" of foam.. what would you put down 1st.. would you want the air gap at the top? or would you want it under the foam.. and I dont know how I could get the foam to sit in up high without falling after the cardboard void form turned to mush.
