My home will have a three car garage extending off the main home. Three garage walls will sit on basically a footing 4 feet down instead of 8 feet down. My question is since I am installing radiant heat into the garage should I waterproof the walls? The radiant is not intended to keep it at 73 degrees all winter (Zone 5). It is more to keep it at 60. I plan to put 10mil plastic underneath the slab with 2" foamular 250 and insulate the walls with 1.5" exterior XPS and intelloplus on the inside wall as a membrane.