i am slowly adding infloor tubing under ceramic tile / plywood / 1" umplained boarding floor. My designer recomended double  1/2 " PEX runs between the joists with the appropriate radiant barrier and convection bat insulation under the radiant barrier.

my question is the method of attaching the tube to the underside of the floor. some designs recomend right against the floor, one said just against the joist near the floor.....i plan to base load the floor and use my pelet stove for the very clod weather. having said that the "plates" which from what i see only increase the feat transfer rate will not help.


what is the best method to secure the PEX and where. the gap i was told between the floor and the radiant barrier should be no more that enough so the barrier does not touch the PEX

thanks