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as Carol applies the finishing touches
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layered with beauty
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Li and I busting it out
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moisture control is a must outside too
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to custom mix a slab
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the look of cautious optimism
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I wish you could feel the hospitality of this floor. Just keep a broom handy.
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Notice the ‘marbled’ mottled look that we unwittingly achieved.
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Final finish on our first earthen floor.
The story of Ellie’s Earthen Floor is a memorable one. It is a story that is steeped with the very essence of experimentation with building techniques. This particular technique, Earthen Floors, is a highly challenging flooring method to get quality results with in our wet climate here in the Southeastern US. In order for us to even get a proper small scale experiment together it required a whole season’s worth of applying large bursts of work at well-timed intervals. Even with the best of intentions and lots of willing hands around to help out, we were still met with a vast amount of adversity. The weather was certainly not our least adversarial force. Our effort in earthen floor R&D took place during one of the most rainy and humid summers I can remember. Therefore, the result of all of our toiling and tinkering is one small step toward making this technique work in subtropical conditions and a multitude of vital lessons about that ever-so-important interface of moisture and materials.
Our earthen floor experimental station was one of the better products of workshop and volunteer labor at the ETC, known as the hippytat. Coming into the season my dear friend Ellie decided that she would like to take up residence in the hippytat, but the moisture content of the space suggested against it. Everything that entered the space eventually mildewed or molded. But we needed that space. So, our solution was to excavate the existing dirt floor which was essentially the soil that was there to begin with and to replace it with all the proper stages of an earthen floor. Armed with mattocks and shovels, we went to work. We used the soil we extricated to raise up a garden bed behind the structure. Then we replace the foot and a half of soil with large stones and gravel up to about four inches below our eventual finished floor height. This would provide the capillary break required by a floor made out of clay and sand. The gravel and stones prevent water from making its way up through the soil during wet weather events. At this point, a glance inside the small hermitage would reveal a room full of rocks. Not very hospitable… yet.
Our next big push was to install the ‘poured earth slab’ on top of the gravel capillary break. The 3-4 inch thick slab was a mixture which is analagous to the super adobe mixture which is used to fill earth bags for foundations and ‘ceramic’ domes. The mixture is simply clay, sand, lime, fiber, and just enough water to make it take the form or the floor. It dried perfectly, as it just so happened to be put in during the small window of dry weather during the summer.
Next came the layers of the finished floor. We first installed what became our base layer to bring the floor up to as smooth of a surface as we could muster. Our intention was to test the moisture combating action of the layers below by installing a layer without an antibiotic element, thus allowing us to maintain the full luster of the clay that Ellie wanted to color her floor. However, as the weather became increasingly moist and rainy, it became apparant that this was not an option. So we dosed the base layer with a coat of limewash in order to raise its alkalinity to a level inhospitable to mold and mildew. This was the source of our first valid learning: that no layer of earthen material installed in this climate needs to go without an appropriate does of some antibiotic/growth inhibitor such as lime or borax. Lime is the natural choice since in most every case it will improve the hardness and durability of the mixture.
Then we began to apply a final, finer and lime rich coat of earthen floor finish. With the help of two young artists, Darien Flores and Sarah Hewitt, the final coat went down and the most trying aspect of the process began, the finishing oil. Since receiving a coveted copy of Bill and Athena Steen’s Earthen Floors we had consulted it for all of our proceedings. But on the finishing oil application, it turns out we didn’t follow closely enough… After giving the floor almost two weeks to dry out following the final earthen layer, we decided to begin applying the linseed oil at full strength on the floor. Wouldn’t you know it, puddling occurred. It turned out that the humidity during late August/ Early September was consistently too high to allow the earthen layers to dry out fully. So, where the oil would normally have penetrated into the interstitial spaces around the sand and clay, hardening it to a fine polish, it was not allowed to do so, due to the remaining moisture content. Instead of penetrating, the oil formed a hardened layer on the surface of the floor, which had to be scraped and buffed off and followed up with another oiling once the floor had dried. This was a hard won lesson indeed. If one were to want professional results and a clay pot, almost leather, looking floor like the experts achieve in the Southwest, every aspect of the installation process would have to be timed perfectly with the seasonal changes in humidity and with the finicky local weather patterns. In our case, that would mean timing the process so that the final coats would be going on during the driest months of the summer, June and July. Practically speaking, it is very tricky, but it is doable. However, all things considered, my final verdict would be that earthen floors are just not regionally appropriate here in the SE. I hold that same opinion for a lot of building techniques which continue to be employed by hundreds of professionals, such as in-ground basements, the overuse of impermeable membranes leading to rot and mildew, and sprawling brick McMansions that consume exorbitant resources throughout construction and the life of the building. I digress.
We do undoubtedly need to explore more ecological solutions to every aspect of our built environment. This exploration of earthen floors has proven to hold valuable lessons, and I look forward to going back to check up on it’s performance in years to come.
Do good works and play dirty!