Hello,
I’m a fairly new builder in the Midwest and am looking for insight on a particular question.
We’re building a fairly large house in Climate Zone 4 (between KS and ST. Louis) and by fairly large its just under 7,000 sq/ft including the daylight basement. Client is not too concerned about energy efficiency but is open to my input on these issues. 
A few details about the build.
As mentioned, daylight basement with approx. 140 ft. of  cement basement wall and 140 ft of framed basement wall. Full second story plus attached 3 car garage.
Heating will be air sourced heat-pump.
We’re installing 1″ of insulation under-slab and between slab and all concrete foundation wall. Cement walls will get 1″ of insulation followed by 2×4 framing and batt insulation.
Wood framed walls will be 2×6 with BIBs, wet-blown cellulose or maybe batts of some type, followed by 1/2″ sheeting and 1″ of external foam and then WRB.
The ceiling will be blown in cellulose or fiberglass @ R-60. 
So here’s the question. 
I bought the below grade foam from Thermal Building Concepts https://www.thermalbuildingconcepts.com/index.html
He has a product that comes in 3/8″ and 1/2″ thick rolls that are 4×72′. He really recommends these for the ceiling applications where the foam is installed directly to the bottom of the ceiling joists followed by sheetrock. He says the blown in insulation will store the heat that the attic collects during the day and the ceiling joists will radiate that heat into the interior. And his solution to stop this is his foam product. He says it will stop heat from the attic without any additional airspace (blow in directly on top of it) and will yield considerable energy savings. While he does have some technical data, he has nothing on ceilings in particular. https://www.thermalbuildingconcepts.com/technical/
Interested in hearing your thoughts. I’m a little skeptical but if anyone had done it with good success I’d be happy to hear.