10 Aug Site Work: Underslab Insulation Installed
The flowable fill discussed previously has created a quick, even pad on which a layer of high-density expanded polystyrene insulation is installed. The insulation sheets come in large sizes – 4’ x 16’ x 6” thick – making them quick and easy to install. Our total installation time with only two people involved was about an hour. Typically a building sits right on top of a concrete foundation, without any separation from the ground. Imagine standing outside with a heavy wool coat on and no shoes — your coat is trying to keep your body warm, but you are losing a lot of heat through your feet. When you put boots on, you are separating your feet from the ground and providing a better insulation. Adding a layer of insulation on top of the flowable fill creates a barrier between the foundation and the ground. This separation provides a complete thermal and moisture break between the earth and the building’s concrete foundation, just like boots prevent your feet from getting wet and cold. Supplying the building with a highly insulated foundation allows the house to retain more heat than in a conventional construction practice where there is no separation between the house and ground. 
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