|| Adobe and Flagstone Floor || Earthbag Foundation || Papercrete Wall Finish || Ventilation Design || Windows Imbedded in Papercrete ||
Goals of Innovation: To use natural, local, thermal mass materials to make the floor.
Description: Over the sub-floor of scoria and plastic, about 2" of road base was compacted, and then local adobe (clay and sand) was mixed with water and chopped straw. This was poured and trowelled to a layer of about 2 more inches. As dried over several weeks, it was periodically pressed with a steel trowel to eliminate shrinkage cracks and to produce a hard polished surface.
Obstacles: Further compaction of the sub-floor and shrinkage cracks made it necessary to score the adobe in an irregular pattern to hide the cracks.
Cost Information: The adobe and straw were free; the flagstone was about $1/sq.ft.
Additional Benefits/Drawbacks: The adobe provides a naturally beautiful and resilient surface that is easy to walk on. It does require some maintenance, but this can be done fairly easily by reapplying a layer or two of linseed oil once a year. Other than that, it can be cleaned with a damp sponge mop.
Goals of Innovation: To make a stable foundation that required no concrete, steel, or extensive excavation.
Description: The foundation is simply the first course of earthbags (filled with crushed volcanic rock) laid directly on the naturally draining sandy soil at the site. Other than leveling the site, there was no further excavation.
Obstacles: Building codes would certainly have been an obstacle if our county had employed them.
Cost Information: There is no extra cost to this technique; it eliminates the costs of traditional foundations.
Additional Benefits/Drawbacks: This is an easy and effective way to support a domed structure. Different soil types might require a rubble trench or French drain system. The owners have been completely satisfied with the performance of this foundation technique. There is no indication of shifting of the building from frost upheaval or other forces.
Goals of Innovation: To provide a highly sealed and insulating exterior plaster to protect the earthbags from ultraviolet radiation and weather abrasion.
Description: 2" chicken wire mesh fencing was attached to the earthbags with polypropylene baling twine or wire staples. Papercrete plaster was made on-site with recycled paper, local sand, and Portland cement. This was applied by hand and left a hand-printed texture.
Obstacles: In some cases, "cold seam" cracks appeared between successive applications of the plaster, but this is just cosmetic and had no adverse effect on the integrity of the plaster or moisture penetration. Among papercrete's qualities are that it can act like a sponge. When papercrete contacts water, it soaks it up, holds it, then allows it to evaporate over time.
Cost Information: The only cost incurred for the papercrete was just the cost of the Portland cement, about $0.07/sq. ft.
Additional Benefits/Drawbacks: The papercrete plaster is very durable, requires little to no maintenance, and is completely breathable. In the fairly arid climate of this home, there is no need for a moisture barrier. Papercrete does, however, absorb a tremendous amount of water, but it does not allow that moisture to migrate into the interior of the wall. The moisture simply evaporates when conditions change.
Goals of Innovation: To adequately ventilate the entire house in ways that allow it to stay warm when the weather is cool and cool when the weather is warm.
Description: In addition to the seasonally adjusted inlet and outlet vents, there are a few screened windows and doors that can open to let in additional air. An adjustable speed fan is installed in the large dome to help mix the layered air. The greenhouse is vented directly by lifting the hinged glazed roof, and opening inlet air window vents.
Obstacles: There were no obstacles to installing this system, nor are there obstacles to operating it.
Cost Information: The cost of this venting system is estimated at $150.
Additional Benefits/Drawbacks: Due to the height of the domes, warm air tends to accumulate in the upper lofts. Fans and nighttime ventilation tend to mitigate it, however.
Goals of Innovation: To create a technique for installing windows that allows the use of odd sizes of glass that is completely sealed from the weather.
Description: The window openings were created with earthbags surrounding old wagon wheels or culvert couplers. Recycled glass is imbedded directly in the exterior papercrete plaster to cover the opening. The papercrete is so dimensionally stable under all climatic conditions that the glass does not break as it likely would if imbedded in ordinary stucco.
Obstacles: Some of the seals in the thermalpane windows have leaked moisture and fogged the glass.
Cost Information: The total cost of all the glazing in this house was under $1,000, because it was acquired as seconds or surplus from glass shops.
Additional Benefits/Drawbacks: Aside from a few fogged windows, the owners have been quite satisfied with the results.