Whether you’re building slab on grade, crawlspace, or full basement, what happens below grade has a massive impact on the comfort, durability, and health of the home above. Travis breaks down practical strategies for managing moisture, air, heat—and even radon and termites—below the floor. From drainage and waterproofing to insulation, vapor control, and air sealing, Travis walks through the materials and methods that create high-performance assemblies from the ground up. If you’re aiming for warm, dry, and durable foundations, this is where it all starts.