DIY Cob Cabin

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Photo by Miguel Elliott
A tiny cob cabin can serve as an office, playroom, or studio.

In 2016, I moved to California to build a “palletable cobin” — a cabin built with heat-treated pallets, insulated with straw, and covered with cob. I wanted a durable, well-insulated tiny cob house that didn’t require too much time or money to build and could be made out of recycled materials and local resources. I planned to build a 120-square-foot hut, which wouldn’t require a building permit. So, as soon as the weather cleared in May, I set aside loose topsoil, brought in a few cubic yards of base rock, and tamped it all down firmly. I had a collection of used cement pier blocks that I set in a 12-foot-diameter circle about 40 inches apart from each other — the same width of the pallets I had available. I used chunks of concrete and sandbags filled with base rock to fill in the spaces between the cement blocks and provide a solid foundation. I then prepped the pallets by adding wood to the backsides in places where backing was absent.

After all the pallets were prepared, I screwed 4-by-4-inch upright supports to the pier blocks, and then attached the pallets to the uprights with 3-inch screws. I had the windows I planned to use on hand, as I knew they would affect the spacing of the uprights and the size and placement of pallets for those sections of the wall.

After setting the first round of pallets, I stuffed a flake of straw, which was about the same width as the pallets, into each pallet for insulation, using a pole to pack it firmly. We used about 2 bales of straw to insulate the structure. Eco-bricks could also be integrated at this point for additional insulation. Next, I framed in my windows and added wood pieces for shelving. Some areas needed to be finished with cut pallet boards for proper spacing, and then filled with straw. After all the walls were up and insulated, I connected the tops of the 4-by-4 uprights with 40-inch-long 4-by-4s, cut at the proper angles, upon which the rafters for the roof would sit.

Having spent just three days framing the hut and getting the windows in place, I then hosted a work party to cover the pallets with cob. We used soil with high clay content right from the property, and mixed it with about 60 percent sand and some straw. To make the mix, I use a rubber box, or “mud box,” and a hoe, and then I cover it with a tarp and stomp on top. The entire mixing process can be done with a few friends willing to dance barefooted atop the tarp. You could use a cement mixer, but I’ve found it doesn’t save much time and is an unnecessary expense.

I was happy to discover that the cob didn’t require any sort of chicken wire or burlap mesh covering the pallets to stick. We made a clay slip — a mixture of clay and water about the consistency of a milkshake — and sponged it onto the pallets to serve as glue for the cob. We then applied cob to the pallets about an inch thick, and smoothed it with wet hands or rubber gloves.

During that weekend work party, we covered all the pallets with the cob mix. Then, we celebrated by cooking pizzas in a nearby cob oven. The next day, we added extra cob around the windows and sculpted decorative cob trees around the doors with leftover cob.

Finally, we built the roof of the cob cabin in about three days, using 2-by-6 rafters with a skylight in the middle. We set 3⁄4-inch plywood with a rubber roof membrane on top, which we then covered with about 6 inches of earth to create a living roof. After placing metal flashing around the skylight, we put earth on the outer area of the skylight. The roof has a 20-inch overhang around the structure to keep rain off the cob walls.

After about 10 days, the walls of the cob cabin were completely dry and ready to plaster. On the outside of the cabin, we applied a hydraulic lime plaster with a brown oxide. On the inside, we used an earthen plaster with clay paint. We also did the floor in cob, which took a few weeks to completely dry. We then added plaster and sealed it with a few coats of linseed oil, with thinner added to help it penetrate into the plaster.

To create a more artistic hut, glass bottles or stained glass can be embedded in the walls during the construction process. Additional sculpting can add decoration and whimsy to the hut, and completely conceal the regular square pallets used for the internal framing.

This is a great method for creating low-income, eco-friendly housing. Well-insulated, affordable structures can be built in just a few weeks without many technical skills. For a structure to be legal to live in, however, it needs a permit, which requires an engineer’s stamp for code approval. If the frame is built as a gazebo, with post and beam framing, then the pallets will just be infill and won’t provide any structural strength. If electrical and plumbing are added, these should be done by somebody with experience in those fields to avoid injury and mishaps

Each region has its own legal constraints that you’ll need to investigate for legal occupancy. Check local building codes for your area. After you’ve cleared those hurdles and constructed a sturdy cob cabin, this newly created space can make a great office, playroom, massage studio, and more — a “palletable cobin” has endless potential.

Miguel Elliott, aka “Sir Cobalot,” was “cobverted” about 20 years ago, and has since traveled the world sharing his craft. Through his business, Living Earth Structures, he specializes in building community ovens, benches, saunas, and “palletable cobins.”