My room mate and I are having problems with our front porch sinking. We placed stones under the part that was sinking about a year ago and a couple of days ago we used an expandable foam for a quick fix, but now we want to fix the problem the right way. We have used a jackhammer to break the concrete up and now we are trying to figure out how to set the new concrete slab correctly. Does anyone know have to do this? Any information would be great. Thank you.