Here’s a photo of the nearly completed footing, show the narrow footprint of the house. As I noted in an earlier blog, this footprint allows sunlight to penetrate deeply into the house, so each room is heated by the sun.
As you will see in subsequent blogs, I placed 5 inches of rigid polystyrene foam under the floor for insulation. I used pink board, that is, XPS or extruded polystyrene, which has an R value of 5 per inch. R-25 may seem like an awful lot of insulation, but remember, the ground beneath a home remains a constant 50 to 55 degrees and can suck a huge amount of heat out of a home during the winter. If you don’t insulate and insulate well, your house will be much colder than you would like.
The Department of Energy recommends R-25 insulation under floors over unconditioned spaces. That means crawl spaces and, to me, under slabs.
Contributing editor Dan Chiras is a renewable energy and green homes expert who has spent a lifetime learning life’s lessons, which he shares in his popular blog, Dan Chiras on Loving Life. He’s the founder and director of The Evergreen Institute and president of Sustainable Systems Design. Contact him by visiting his website or finding him on Google+.