I will be putting up a Victorian conservatory and am looking for the best foundation option. I was told I could pour a slab of cement 4" thick on 2" styrofoam and that would suffice. I was also told I could pour a foundation and build a wood floor over an enxisting cement slab. I would like to know the most functional and least costly as this room is quite heavy and I don't want anything to happen to it! I live in Michigan and it gets quite cold here. I would really appreciate your advice on this quandry!!