After the walls were poured and workers were out of the way, I laid the PVC pipe for waste water drainage.
We are installing a composting toilet, so these pipes will carry gray water from sinks and the shower to the septic tank, then on to our lagoon from which we hope to irrigate pastures during dry spells. (We have not leach field because of the extremely high clay content of the subsoil.)
Once the rough plumbing was in and I’d passed inspection, my workers and my son Skyler and I laid five inches of XPS (extruded polystyrene) insulation down over a layer of 6 mil polyethylene (below). We laid down 2 two-inch 4 x 8 sheets and one one-inch 4 x 8 sheet.
We alternated the sheets of the polystyrene so there were no open gaps. This process went quickly but did present some challenges. Working around conduit from the solar and wind systems and rough plumbing required extra effort.
After the PVC moisture barrier and foam were laid down, our concrete company (Unerstall Foundations, Washington, MO) brought in its crew and poured four inches of concrete over the foam (below).
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+.