I am building a 40×60 metal workshop. It is slab-on-grade and I had specified 2″ rigid foam on the interior of the stub wall, thus creating a thermal bridge between the foundation and the slab. The footing and stem wall have just been poured. I think there has been a mis-connect between my contractor and myself because it looks like he is going to place 2″ thick rigid foam only in the space between the footing and the slab (i.e. the 4″ slab will be “faced” with 2″ thick rigid foam… in other words, the foam will extend from the top of the slab to the bottom of the slab, but will not continue down the stem wall to the bottom of the footing. I live in Oklahoma, Climate Zone 3 and the workshop will be in constant use. Is this acceptable, or will I lose most of the benefit of interior insulation of the slab wall by not extending the 2″ thick rigid foam downward to the bottom of the interior stem wall? Sorry for the looonnnggg question, and thanks for any assistance.