Mother's $10-per-square-foot (or less!) Earth Sheltered House: Part III

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Then again, we did give our experimental waterproofing setup the best backup possible, by installing a thorough drainage system around the walls. A perforated, 4" ABS pipe runs all the way around the junction of the footing and foundation, lying in a 12" bed of gravel. This pipe helps channel water away from the crucial joint between the concrete footing and the block foundation. Another 4" ABS pipe is set four feet above the footing on the fully bermed eastern portion of the wall. This pipe is also positioned in a bed of gravel to prevent it from becoming clogged with mud.

PULL UP THE COVERS

The exterior insulation for the building is extruded, skinned polystyrene foam. Two 1" "pieces extend down three feet below grade. At that point, the inner layer continues down to (and overlaps) the footing. The outer 1" piece, however, is cut at the three-foot line and flared out at about a 60° angle from vertical. This leaves a one-foot-long skirt around the building to close off a direct path for heat to travel from the footing and wall to the surface. (In addition, the impermeable material helps route water away from the walls of the building.)

Our roof insulation consists of one layer of unfaced 3-1/2 "fiberglass that's been pushed up between the rafters, with another layer of faced 3-1/2" fiberglass placed beneath the first and stapled to the beams themselves. No further vapor barrier was deemed necessary for our climate, but those of you who are building in areas with 5°F or lower design temperatures should seriously consider using a polyethylene layer to protect the insulation from condensation. Furthermore, a well-sealed vapor barrier would cut down heat loss caused by infiltration.

SPLISH SPLASH

Finishing the interior and connecting all the services of a home are areas where a huge part of the construction budget can be eaten up. Anyone who's shopped for cabinets, lights, or cast-iron plumbing fixtures will attest to that. Therefore, we devoted a great deal of attention to finding recycled components wherever possible and searching out low-cost solutions when scrounging proved impossible.

Our building's cast-iron bathtub, for example, was purchased at a salvage yard for $30. This was a significant saving over the $300-$400 we would have been forced to pay for a comparable new one. The tub's porcelain surface is in fine shape, and the design is only slightly dated ...that's something we can easily tolerate in order to save three hundred bucks! Similarly, we got two sinks—one in white porcelain for the bathroom and one in stainless steel for the kitchen—for a total of another $30. When it came to the commode, however, we found far fewer acceptable options.

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