Sunday, May 10 2009
I finished the ditch on the greenhouse's eastern side, just below the east window, and then started assembling a subterranean skirt of styrofoam. Often when I work with styrofoam, particularly as a covering for rough surfaces like soil, I feel like I'm improvising a particularly crappy homeowner fix (referred to in my family as a Rowe-Rodecap fix, after the two previous owners of my childhood home). But the great/terrible thing about styrofoam is that once it's buried, it lasts forever and doesn't degrade. If I manage to get a reasonably-intact layer of styrofoam between two layers of soil, heat will have difficulty moving between those layers. And even if the styrofoam isn't working as a great foundation insulator, it's out of sight and out of mind and I have a justification to clear whatever register in my mind is concerned about the leakage of heat in that particular part of the foundation.
I covered the styrofoam with rocks, starting with gently-places flat ones and working my way up to large boulders carried from the nearby woods. Eventually I will build a retaining wall on the north side of the door well, and I will want the foundation for this wall to be a nice well-drained base of rock so I don't have to worry about it shifting around when the ground freezes.
Later I used the last of a 94 pound back of Portland cement (mixed with some leftover mortar mix) to seal up the joints in the north-side exterior Wonderboard panels. And then I prepared the north wall for its final treatment, to serve as a retaining wall for four feet of soil. The soil exists in a large pile immediately north of the greenhouse, a pile that resulted from the site's excavation. But before this soil could be shoveled into place, I needed to finish up some details. The biggest of these was a ten foot piece of four inch PVC pipe covered in rock that will one day allow me to circulate air from inside the greenhouse through the rocks buried on the outside of the greenhouse. So I needed to complete the piling of rock around this PVC pipe and then I needed to bundle it all up beneath a tidy black sheet of finely-perforated plastic fabric (allowing water to pass but holding back soil).
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