by Athena and Bill Steen - Cohabitat

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Depending on site conditions, a well constructed earthen floor may consist of several layers. Preparing the Base To help prevent the floor from cracking or settling, the ground should be well compacted an free of all movement All organic and plant matter should be removed. If very expansive clay is present, it should be removed and replaced with another non-expansive soil or other substitute. The ground should also be dry before beginning construction of the floor Waterproofing and drainage If the capillary rise of moisture is a problem, steps need to be taken to improve drainage and stop the upward movement of moisture. For many situations, a layer of 6 to 12 inches (15 to 25 cm), of either dry stone topped with gravel, gravel, or coarse sand may be adequate to improve drainage and stop moisture migration. Certain volcanic stones like pumice could also provide the additional benefit of insulation as well as protection from moisture. The uppermost portion can be comprised of finer gravel or coarse sand to prevent the upper layers of the floor from falling through. If more drastic measures are required, plastic or petroleum based membranes can be laid down, to prevent capillary rise, but at the cost of losing the b readability ofthe floor and contact with the earth itself Preferably, this membrane should be laid with care on top of a layer of sand to avoid any tears or punctures. If a non-synthetic, water-tight barrier is desired, a thin layer ( 1/4" to 3") of soil with a high clay content or bentonite can be used. It can be applied in a moist state in several layers, filling all cracks as each layer dries. Troweling each layer will help compact the clay mix and reduce the pore space. This will further aid in creating a water-tight seal. The top layer in particular needs to be wellcompacted. Bentonite sheets (1/4 H thick, backed with cardboard), can also be purchased, although more costly. (See resources.) It might be possible that the application of a lime plaster which has been stabilized with a water-resistant material, like prickly pear cactus gel, could be effective as an anti-capillary barrier Whatever approach is used, it should be tested first to determine if it performs well.
Insulation For insulation, 4 to 6 inches (10 to 15 cm) of straw/light-clay (see formula below), perlite/clay, pumice fines, or expanded day (clay that has been heated, expanded and filled with small air spaces) are some of the natural options that can be laid on top of the gravel or drainage layer. If desired, one can always resort to rigid foam insulation. Clay Slip A clay slip acts as the "glue" that binds together the straw or the perlite in straw/light-clay or perlite/clay mixes. A soil with very high clay content can be passed through a 1/8" screen to remove small stones and other debris. It is then mixed with enough water until it has a consistency of a latex paint. When a finger is dipped into the mixture, a coating should remain that obscures one's finger prints. Straw/light-clay Gay slip is slowly poured onto a small quantity of loose straw (2-3 flakes) at a time, then mixed either by hand or with pitchforks, until each straw is coated with clay slip, similar to tossing a giant salad, when the straw sticks together in a bundle when tightly squeezed, the mix is ready. To keep the mixture from drying out while more is being made, it can be stored under a tarp. If allowed to sit for a couple of days, the mixture matures and improves. The straw/light-clay needs to be tamped such that poorly integrated layers are not created. The butt end of a 2x4 works to tamp and work the mix together. Upon completion, the straw/light-clay needs to be solid and not spongy. J *A solid and compact layer of straw/light clay requires practice and can be somewhat labor intensive. Mixing Straw/Light Clay
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Page 7 and 8: Mixing Test Samples for Finished Fl
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Page 13 and 14: Earthen floors can be divided with
Page 15 and 16: Periodic Applications of Coat 4" ca
Page 17 and 18: Yavapai Sports Surfaces P.O. BOx 17

by Athena and Bill Steen - Cohabitat

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