2018 IECC requires heated slab-on-grade assemblies to have both vertical edge insulation and
a minimum of R-5 continuous insulation below the entire slab.
The vertical (slab edge) insulation construction details you specify in this screen and in the
envelope table should represent the insulation that starts at the top of the slab edge and extends
downward or downward then horizontally around the perimeter of the slab.