We are remodeling this summer and plan to put in radiant floor heating throughout our house. We will be replacing all the current flooring, all interior doors and two exterior doors, so a slightly higher floor from the Warmboard will not be an issue. We originally thought we would go with Warmboard, but our contractor is suggesting staple up with heat plates. We are concerned about going with our contractor's suggestion. Our concern is this. Our house sits on a steep slope. The bottom floor sits about 7-8 feet above the earth and is always cooler by 5-10F (or more in the winter) than the rest of the house (even with our current forced air heating). With the open space below the bottom floor, even with insulation, we worry that not all of the heat will be forced up into the bottom floor of our house. Instead we will have some heat loss from the staple up heating system into the open space below our house, thus negating some of the benefit of the system. Is this a legitimate concern? Should we insist on the Warmboard system?