Natural Building – Making An Earth Bench

A few weeks ago, I was offered the opportunity to take a Natural Building course in exchange for assisting Lola and May with the course preparation. Being a building intern at the Panya Project, I jumped at the opportunity to learn more about some of the materials and techniques that are used in natural building.

The first day was primarily in the classroom learning Natural Building Theory, including the advantages of building your own home out of earthen materials. In addition to being very low cost, being able to design your own home in a way that exists harmoniously with the surrounding ecosystem can be a fun and empowering experience!

After discussing reasons why a person might want to use natural building methods, we started talking about the logistics of building an earthen structure; starting with a recipe for mud building. The two most common forms of mud building are cob and adobe bricks. Cob is a mixture of mud and long fibers, like straw, that you wind around a structure to build and strengthen. It is used while wet. Adobe bricks are made of mud mixed with short fibers, such as rice husks or chopped straw, that you form into a brick shape. Once the bricks are dry, you use mud as a mortar to build structures with them. The mud mixture for both cob and adobe needs about 70% sand and 30% clay. As a practice, we walked around Panya taking samples of the subsoil from different areas to test how much clay is in different parts of the farm. This is especially important if you are trying to build your own house on a plot of land, because some parts of the land may have better soil for building than others.

That afternoon, we hopped in the mud pit. To create the mud mixture, we stomped in the mud to smooth out any lumps and made sure we had the correct mixture of sand, clay and water. Once we had it right, we added the rice husks and continued stomping to mix it all up. When it was finally ready, we filled up several wheel barrows full of mud and poured them into our brick molds, which look like ladders. You drench the ladder in water so that the mud doesn’t stick, then lay it on the ground. You then pour the mud into the spaces, make sure they are nice and even, then lift the ladder up. If the consistency is right, the mud stays on the ground in a perfect brick shape and can be left out in the sun for a few days to dry. Our mud bricks were successful and we made about 70!

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Stomping in the mud pit, mixing up our brick recipe.
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The bricks we made using just earth, water, and rice husks!

The next day, we started our design for an earth bench. We started off in the morning by discussing how to lay a foundation before heading out to the site to start the project. First, we laid out where the bench was going to go, sprinkling flour to ‘draw’ out the shape. We had to take into consideration that the foundation needs to be an extra 12 inches wider than the bench will be, on each side. This is so any water around the bench can drain into the ground instead of wicking up into the bench.

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This is the site where we built our bench. It’s at a crossroads in front of the dorms, so it’s a good place for a place to sit and hang out.

Once we had our design marked out, we started digging. The foundation for a house would need to be deeper, but for the bench, we dug down about 10 inches. Once we had the entire shape dug out, we tamped the earth down using our feet and homemade tampers, to make it stable and even out the surface.

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Digging the foundation.
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You can see where we marked out the shape with flour
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Using our feet and homemade tampers to make the foundation nice and solid.

The next step was filling the hole all the way up with gravel. After filling up several wheel barrows of gravel and pouring them into the foundation, we tamped the gravel down using the same technique as before. At this point, we realized that our bench was being built on a part of the land that was going to collect water, so we had to figure out a solution to avoid the bench getting flooded and risk water wicking up into the bench (which could cause mold, crumbling, and other issues.) Our solution was to dig a trench that lead from the bench foundation to a nearby tree. We dug the trench at a downward angle away from the bench so that the water would be redirected to the tree and plants growing around it. We then filled the trench with gravel and tamped it the same as the foundation. After it was tamped, we covered the trench in burlap sacks to keep dirt from clogging it up, then covered the sacks in dirt to conceal it.

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Digging out the trench to redirect any water collecting around the bench

While one group was digging the trench, the other group was starting to build the bench structure. The first layer was made of gravel bags-literally bags stuffed with gravel, then tamped down to make them flat. We put them down as close together as possible to create the first layer of our bench. Once the gravel bags were in place, we added two layers of earth bags, which are the same as gravel bags, but they are filled with soil. We also put a layer of barbed wire between each layer of bags to hold them together. We tamped down each layer to make them nice and flat before calling it a day.

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Laying out the shape of our bench with one layer of gravel bags and two layers of earth bags
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Celebrating after a hard day’s work on the beginnings of our earth bench

The next day we pretty much just jumped right back into working. We were almost ready to start laying bricks, but we first had to cover the earth bags with chicken wire, which gives the mud something to hold onto. Then we had to jump back in the mud pit to make mortar for our bricks. The mortar we used was the exact same mixture as the bricks we had made, we were just using it wet instead of making bricks out of it.

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Covering the earth bags in chicken wire to give the mud something to stick to
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A closeup of the chicken wire covering the earth bags
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Lola showing the class how to make cob

Once we had the backs wired and the mortar made, we started laying bricks. One of the great things about adobe bricks is that you can easily shape them. So in areas of the bench that we wanted rounded or cut in an unusual way, we could easily shave off parts of the bricks with a machete.

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The first layer of bricks!

We also had to start building the back rest of the bench, for which we decided to use cob. We built a frame in the shape we wanted out of bamboo and wired it to the chicken wire on the earth bags, then used cob to wind around the bamboo and build up into the back of our bench.

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More brick laying and beginning to build the back of the bench using bamboo
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Starting to clean up the shape of the bench

On day four, we were back in the classroom discussing Ecological Home Design, which consisted of a discussion about how to create a home that is part of the ecological system it exists in, using local and renewable resources, making it practical and functional, and the least damaging to the natural environment. We talked about the issues surrounding modern building techniques and how natural building techniques are a preferable solution. We also discussed methods of using the natural environment to your advantage by positioning your home in a way that makes use of the sun, using natural insulators, and taking advantage of prevailing winds, depending on what type of climate you are living in.

We then got back to work on the bench, finishing up any sculpting and shaping that needed to be done, and covering it with the first coat of plaster, which is known as the scratch coat. The scratch coat was the made of the exact same mixture as the mortar. Just sand, clay, water, and rice husks. We then watched a slideshow presentation of different types of earth homes all around the world, and took a tour of a neighboring farm called Pun Pun-another permaculture farm that is pretty famous around Thailand and a great example of functioning permaculture system.

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Finishing the scratch coat – the first layer of the plastering process
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More scratch coat – making sure all of the gaps are filled and the shape is really solid
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We even included some fancy cup holders with PVC pipes at the bottom to drain out any rainwater that collects
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The bench shape finished and ready to be plastered

The next day was all about plastering, and we actually had another plastering project to do in addition to the bench. One of the Panya houses was in need of re-plastering, and we decided that it would be great experience for the natural building students to try out.

For the house, we decided to use a lime plaster, which is just clay, sand, lime, and water. Lime is more water resistant than just earth plasters, but you have to use gloves when working with it because of the alkalinity. To create a nice smooth plaster, we sifted all of the ingredients before mixing them together and then adding water. The result was a beautiful, creamy plaster ready to be slapped on the walls. We put a tarp down on the floor and taped the edges of the windows to try to keep everything clean, though it’s fairly easy to scrape the plaster off of anything that it shouldn’t be on. We then wet down the wall before putting the plaster on to help it stick better. Once we had the walls coated, we used a wet sponge to smooth it out. We got all of the inside and some of the outside done in less than a day.

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Sifting the lime for the plaster – we needed to use face masks to avoid breathing it in
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Sifting the sand for the plaster
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Plastering the house

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The next day, we finished up the outside of the house and we also experimented with some different plasters to use for the bench. Each student got to make up their own recipe, then we voted on the one we liked best. We ended up picking a black plaster, and got to work making a whole bunch of it. This was an earth plaster (no lime) so we didn’t have to wear gloves while using it. Once we had it mixed up, we put the plaster on and had the whole bench covered in a matter of minutes!

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We tested out some different plaster recipes that we wanted to use on the bench.
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We ended up picking this nice black plaster
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Smoothing on the plaster

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And finished! (We did not have time to seal the bench during the course, but we ended up using a mixture of melted beeswax and linseed oil to seal the bench. It makes it very water resistant and fit for being outdoors.)

In celebration of the end of the course and all of our hard work, we ended the night with a huge dinner of roasted veggies in the earth oven (complete with our own homemade cheese!) and some beers around the fire.

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Joe getting excited about the feast
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Everyone cooking together in the kitchen for the last night of the course

The course was really inspiring for me. Not only did we create an earth bench and plaster an entire house in only a few days time, but all of the techniques we learned about in the classroom got me really excited to try new methods of building as well. It was really empowering to see a small group of people work together to create something so beautiful and helped me realize what I am capable of accomplishing. We’ve got some more exciting projects coming up at Panya that I can’t wait to share!

Until next time!

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