Converting a sun room into a 4 seasons room and want to tile surface. Existing slab is out of level as much as one inch at the edges. Experienced heart failure over the cost of a bag of self-level and am curious if I can pour concrete over existing slab to bring to almost level and finish with the self leveler if necessary. Thanks in advance for help!

PS, house is in Detroit and porch may not be heated 24/7. Thanks!