I have finished rebuilding my deck and screen porch and now need to fix the stairs. I need to replace the stair treads and fix the settling that has occurred. Currently the base of the stairs sit on a green treat 6 x 6 that sits directly on the ground. I want to raise the stairs to the proper height. I am thinking about putting in two piers with a footings to support the 6 x 6 to prevent future settling. I know I need to go down at least 42 in Minnesota but am wondering how large of a pier I need. I would like to keep the pier size as small as possible to reduce the amount of cement I need to haul and mix. So my questions: 1) How large of a pier do I need to support six steps that are 4 6 wide? I thinking about a 4 6 pier and then flaring out the footing at the bottom?. 2) Would a piece of rebar down the center of the pier help for added strength? 3) I have seen pier forms that are 8 to 10 inch but not smaller. Would a PVC pipe of some kind work well as a form? What else would work in a 4 6 diameter?