franz fripplfrappl wrote:
Thinking about replacing an old porch this summer. Central Wisconsin.

What is recommended depth for footings of corner posts?
At least 4 feet. Use Sonotube's BigFoot base if possible. At a minimum
wrap the Sonotube in polyethylene to help keeping it in place in the
face of frost heaves. Most decks don't weigh enough to keep a straight
footing in the ground when there are frequent freeze/melt cycles.