Radiant heating is wonderful, though sometimes cost prohibited. Our engineering includes using a floor truss as part of the structural system, thus a mud-radiant system with 2 x 2 sleepers is the recommended approach for this. There is an under-mount system with a reflector shield as well, however it requires a bit more space. In that floor joist you would have little room left for insulation and have a loss of efficiency. There are some options here and we would be happy to discuss this further with you.
NOTE: We do not have a slab-on-grade foundation engineered for this kit at this point, thus radiant heating through a slab is not possible with the AvrameUSA system.