We currently have an Intex Ultraframe 16x32. We just got an 18X34 Doughboy and are about to change over. My questions are about how to put the dense foam sheets from H.D. down. Should i run the peices up to the floor rails, or under them? Seems like under them would be best--that way it wouldn't effect the floor height an inch for the liner.The doughboy liners are for 52 or 54 inch pools, and we have the 52. Most of what I've read seems that people are building rails and walls and running foam boards up to it instead of under. I'm a bit afraid I'll end up with wrinkles if I add the 1 inch foam sheets (we are going to reuse from under the Intex if still in good shape). Any ideas or alternate opinions would be appreciated, as long as you agree with me--or don't.