We are hoping you can help.  We had a home built in Northern WI.  It is supposed to be a frost protected slab/floating foundation.  It has in-floor heat.

We expected the horizontal insulation to be buried nearer to the base of the foundation but as you can see, it lays right on top of the ground.  It is not locked together in any manner, it does not slope away from the house and there is no vapor barrier on top of it.  As you can see in the photo, there are spaces between the insulation.  Our builder says it is absolutely correct and that it is up to us to cover it with rock during landscaping.

This does not seem correct to us.  We expected the insulation to be deeper, slope away from the house and then covered with fill.  

The builder is asking us to sign off on the project and we are hesitant to do so until we know this was done correctly.