Here is what’s specified: I-joists, 3/4″ decking, 1-1/2″ gypcrete with PEX hydronic tubing embedded, then 5/8″ “OSB Sonodeck” atop the gypcrete, and finally, 3/4″ hardwood strip flooring finish.
Question: what the heck is “Sonodeck” and how would you fasten it to the gypcrete?