Figure 402L from ASHRAE 90.1- 1989, shows that the edges of concrete slab floors must be insulated.  The diagram shows several common ways to effectively insulate a slab edge. 

The first two pictures show insulation on the outside face of the slab with a protective element.  Unknown to the authors, this protective barrier is essentially an EnergyEdge product.

ALL STATES must certify that their building codes meet the requirements in ASHRAE 90.1. 

(US DOE, 3/30/2006)