Foundation and Stem Wall

We began our bag work right on the ground of this excavation;these bags became the foundation of our structure. The first row of bags can be filled with gravel to inhibit capillary action from the ground up into the earthen walls. The continuing bag work up to grade consisted of the earthen fill we had prepared previously (Fig. 12.6).

Use the compass arm to delineate the shape of the structure. The angle bracket set on the horizontal arm denotes where the inside circumference of the finished, tamped bags should be. Use this arm when initially placing each bag. Set the filled, untamped bag about one inch (2.5 cm) outside this angle bracket. This will allow for expansion of the bag once it is tamped. The horizontal compass arm must be used for each bag placed around the circle (Fig. 12.7).

Pintar Tren Tuneles
12.7: Use the compass arm to delineate the contour of each bag to conform to the circle.

When this first row of earth-filled bags have been placed and tamped, swing the compass arm around the perimeter to see how well you have done. You may need to further tamp a few bags to meet the angle bracket on the horizontal arm. Or possibly the bags came in too far and need to be pounded outward a little so the angle arm can pass without binding on the bags. Adjust the bags, not the arm. This first row will tell you how the following rows need to be modified to adjust to the proper diameter of the compass arm (Fig. 12.8).

If you read the section in Chapter 3 concerning the building compass, you will have bound or taped a level onto the horizontal arm of the compass. As you rotate the compass arm around to check the

Interior Earthbag

proper placement of each bag in the circle, also check the level of each bag in respect to the other bags. The idea is to keep each row as level as possible. Measure the height of the bags after they have been tamped. The bags we used at this stage of the building process tamped down to a thickness of five inches (12.5 cm). Once the average thickness is determined, it's simply a matter of raising the horizontal arm of the compass the corresponding amount for the next row. Tamp the bags until they are level with this setting.

Several options may be considered for creating the stem wall. Two rows of concrete, stabilized earth-bags, or gravel-filled tires, are all effective stem wall options. If using exterior rigid foam insulation, install way too big stem seated on gravel sill


brane tucked under-stern wall bag


Tu V

brane tucked under-stern wall bag gravel bag

12.10: Honey House foundation detail.

interior floor

12.9: Continue the bag work until the bags are up to or just below grade. This is where the stem wall of the structure will begin.

the foam high enough to protect the stem wall. Another option at this point, instead of insulation or in addition to it, is to install a moisture barrier around the perimeter of the bag work up to the top of the stem wall. (All of this is covered in excruciating detail in Chapter 4).

For the below-ground bag work that we are describing, the dome walls are designed to be vertically plumb (like a yurt, or what we refer to as kiva-style) to provide a little additional interior height. Think of it as a knee wall in an attic. Choose a stem wall height that is appropriate for your climate -usually the wetter and colder the environment, the higher the stem wall. Your individual circumstances are paramount in making these choices (Fig. 12.9).

12.11: Way too big bags on gravel sill at grade.

For the Honey House dome, we began the below-grade bag work using a standard 50-lb. bag that tamped to about 15 inches (37.5 cm) wide. For the stem wall we switched to the larger bags we call way-too-big. We maintained the same interior diameter of the bags below, allowing the way-too-big bags to extend beyond the outside perimeter of the lower bags. We accomplished this by backfilling and tamping the outside space below grade (after installing a moisture barrier) with gravel, up to the level where the stem wall bags begin (Fig. 12.10 & 12.11).

12.12: We made a top, or plan view, drawing to delineate how we wanted the windows and door oriented by sighting the compass arm down the center of the box forms.

12.13: Use the compass to align box forms.

12.12: We made a top, or plan view, drawing to delineate how we wanted the windows and door oriented by sighting the compass arm down the center of the box forms.

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