Is it a good idea to put radiant heat under hardwood floors? I have 3/4 solid wood flooring over 3/4 plywood subfloor. I am thinking of putting radiant tubing under the floor between the joists. My problem is that my wife is complaining about a cold family room and hallway. My garage slab already has radiant tubing in it. It is being heated by way of a geothermal heating system.