Mother's $10-per-Square-Foot (or Less!) Earth-sheltered House: Part II

Enlarge Image Image Gallery 1] Bird's-eye view of the low-cost earth shelter, near completion. [2] A curved top plate must be cut from 2 X 12 to go above the kitchen windows. [3] A Squangle in use. [4] Beams were end-nailed through the first cross rafter. [5] From behind the building, you can see the first layers of waterproofing. [6] Rafters in place above the bisecting wall. [7] The interior partitions must bend to fit the conical rear roof.

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Is it possible to achieve food and energy independence on one acre? Well, with imagination, hard work, and the right one acre, we think it might be done . . . and that's what this protect is all about. Of course, providing most of the basic needs for four people from such a small piece of ground is a tall order. Still, we think it's a goal worth pursuing, and we hope that in this series of articles about our low-cost homestead we'll be able to help some of you in your struggles to increase your self-reliance . . . by doing some of the experimenting for you.

In our first installment, we discussed our plans for this project—which include our round, earth-sheltered home . . . an independent, low-voltage DC electrical system run from hydropower . . . and permaculture agricultural schemes—and described the construction methods used to raise the circular building's block walls. This time, we'll go into the intricacies of framing the domicile. (For readers unfamiliar with construction jargon, we've included a glossary of the terms marked with an asterisk.)

On most construction projects, it's a real milestone when you get to the point where you can have a sheltered work-and-storage area . . . particularly when you're working through the winter (as we were!). Yet before we could get a roof overhead, we had to begin the framing of the round earth-sheltered house by erecting the full-diameter, east-west partition. Because all of our building's rafters bear on this wall, its completion was the key to getting to work on the roof structure. And though the wall is a fairly standard 2 X 4, 16" on-center` partition-with openings left for the bedroom and bath doors-the job is complicated somewhat by the special reinforcement above the door headers and the 1-in-12 pitch* of the top plates* . Consequently, it's a good place to "get one's feet wet" with unsquare framing . . . and to learn some of the skills that will be important to the successful completion of this admittedly complicated stage of our house's construction.

Because the west top plate overhangs the exterior block wall, the main partition can't be framed on the floor and lifted into position, as is often done. Instead, we found it best to start by securing the sole plates to the concrete slab with expansion anchors or a nail gun, so that their centerline bisected the circle of the building. This left the north side of the east sole plate flush with the north side of the pilaster" on the bermed wall.

To match the top-plate pitch, the upper ends of the studs had to be cut at a 5 ° angle for a snug fit. (The calculated dimension of this angle is actually 4-3/4°, but the 5° approximation is plenty accurate.) We started the wall by anchoring the end studs to the concrete block and cutting one of the doubled top plates for each side to the appropriate length.

To support the top plates during framing, it's possible either to erect a temporary center pole as we did—or to prepare the rough opening* for the bathroom door. Because the building's center post bears on the bathroom-door header*, the structure above this opening must be somewhat reinforced. When we reached this stage, we set in a doubled 2 X 12 block to support the east top plate, and stiffened the whole assembly with I/2" plywood on both sides of the header box. In order to serve as a construction post, this rough opening should be put together on the floor, and the assembly should be lifted into position and propped. Then the plates can be nailed to the laminated 2 X 4 central post, the trimmers` from the door frame, and the 2 X 12 block.

The remainder of the framing consists of preparing two more reinforced door headers, where cross rafters tie into the bisecting wall, and filling in the 16" o.c. studs. Though it would be possible to calculate the length of each stud, it proved just as easy for us to cut them to fit. We simply laid each board up against the top plate, marked the cut with a pencil, set the trimmed stud in plumb, end-nailed it through the top plate, and toe-nailed it to the sole plate. After the wall was framed, we went back and added the second layer of top plate.

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