I am in the planning stages of added a 12ft. x 16ft. addition, which will be used as an informal dining area. A local builder in my area is advising me to install a slab foundation instead of a crawl space. He said he will pour a slab then insulate th top with inch and a half styrene between 2x4 sleepers. On top of that would be a 3/4 inch subfloor. He said this would be much warmer than an insulated crawl space. I plan on putting a laminate wood flooring system in this room. There will be no electrical or water pipes in the slab, only a couple of heat ducts, so I really can not think of a reason for needing access underneath. Can anyone tell give me their opion on the matter? My main concern is the warmth of the floor between the crawl and the slab since i live in Michigan.