Jan 21, 2013 · Hope you and yours are doing well. I am starting my foundation Feb 1st, The cabin is being built in central. Alabama, I am using post and pier type foundation, cabin is 20x20 2 story. should I use 4x4 4 ft apart or 8x8 5 ft apart, the holes are already dug 4 ft apart 3 ft deep and I planed on putting crushed rock in the bottom, tamping, then