![](http://photos1.blogger.com/blogger/6887/589/320/ground-layers.jpg)
The crawl space is insulated - including the ground. Starting at the bottom, we have (1) native soil (mostly clay), (2) about 3" of sand, (3) a black poly vapor barrier, (4) 2" thick rigid, pink insulation and (5) about 3" of a mix of sand (trucked in) and clay (from the site excavation).