“I just installed radiant heat in one floor above my garage. I used 1/2 pipe and staple up plates. I then left a 1 1/4″ air space and put 1/2″ aluminum faced rigid insulation. Then I install 9″ unfaced batt r-30 insulation capped off with 5/8” fire rated drywall. About half of the 900 sq ft area is cermaic tiles nat he other half is pine board flooring. GREAT HEAT! Just remember to 1) install a mixing valve to maintain a low water ttemp. Your design temp will be under 120 degrees or less. My watertemp is disigned to be 85 to 90 degrees. 2) always have the water circulator pump pushing the heated water through the piping not on the return side. 3) all loops in the same zone should be within 10 % of each other in lenght unless you go to the expense on insalling balancing valves. Good Luck