I'm getting close to laying some new flooring over existing wood
(half of the building) and rough concrete (the other have of the
building). I'm near the DFW area of Texas. I'm thinking of laying
1/2"x4'x8' rigid insulation sheets over the original floor, then
3/8"x4'x8' plywood, then vinyl flooring. The question I have at
this point is about placing PEX on the floor, 1/2" insulation between
the loops of PEX, then plywood and vinyl to help with heating the
building. The building is about 600 sq. ft.

Thoughts?

Mike