Incorporating concrete free slab with a frost protected shallow foundation – GreenBuildingAdvisor

I am in the process of having my engineer design a home on a frost protected shallow foundation using monoslab, which in my cz 6, I can do a 12 inch depth over 6 inches of non frost susceptible crushed stone. I also am trying to incorporate a concrete free slab for the non structural areas (interiors).

After the time spent by my engineer working on it, he is stating that the two will not work together. He is worried that there is nothing that will interlock the footings to resist overturning. He put a fair amount of time nto it and came to me that a concrete slab will be needed to lock the footings together.

I have reached out to gba in the past and have asked in the Qand A section if I can have this engineered? Many came with the answers that it can, with Michael Maines giving me a detail in which he utilized( which I appreciate)

My question….what is my engineer missing?

I appreciate everyone’s time. This is something I am looking forward to incorporating in my next build and really would love to have a properly engineered fpsf with a concrete free slab.