Here are the floors ready for concrete pouring. From the top down, there is tubing which will hold the hot water for radiant heating, a metal mesh, a foil mat for insulation, 4 inches of gravel, then the earth. There are pipes along the walls that collect any water that seeps up from the ground or though the walls. The plywood on the floor is just for the workers for this morning–they will move that once the cement truck gets here to pour the floors.