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earth • ship - a dwelling designed to bring people into a more intelligent and sustainable relationship with their environment
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01.22.06   Time Warp 2: The Power Shed

The following entry is a recap of progress that was made in the summer of 2005. My attention got diverted toward the power shed in anticipation of my system becoming ready for installation. It was ready, but I wasn't. I had to postpone the power system install until the spring.
The Power Shed:
It occurred to me early on that I'd be needing a separate space in which to install the power system. That is something that the hut video did not address. Presumably, the couple in that video had a generator only. If they had a power system involving solar panels, it wasn't a part of the design plans, nor represented in the final cost. Since I plan to be able to work from this location, I was going to need a source of power. The shed would help keep the small size of the hut very quiet and also permit me to store belongings that I would not need constant access to.
This was a perfect job for the earthbags. With earthbags, the temperature would be moderated to some extent but did not need to be comfortable for people. The bags went fairly quickly, once I got a technique nailed down, and were rather pleasant to work with. First, I filled up a rectangular trench with gravel so the first course of bags would not be in direct contact with the earth where they could absorb moisture (and they will, in spite of the plastic). Then I laid down 6 mil plastic over the stones and placed the first course of bags over that. The plastic was then wrapped back up over this course to the exterior of the space and tucked in under the second course.
The Bagging Technique:
My search for the perfect bagging technique led me from poking holes in the ends and running wire ties through them, to finally purchasing a leather punch, rebar ties, and a tie twister. These are incredibly simple and inexpensive tools which help to speed up the process considerably. The advantage of the leather punch is that it will make it through 2 dozen or more bags, and do it quickly and cleanly. The alternative was poking a nail through the bag every time I needed to get a wire tie through. The leather punch needs to be large enough to accommodate a rebar tie, which has a largish loop at each end. I'd pre-punch 3 holes in the bags, 1 near the ends and 1 in the middle, and a good 4-5 inches down from the top to permit rolling the top down a bit. Once the bag was about 3/4 full of earth (packed down a bit) just below the holes, the rebar ties would get poked through and the wonderfully simple tie twister would get hooked in and synch it up in just a few turns. It works wonderfully. Very little fuss and muss. The ties themselves sell for a nickle a piece, but you can usually get the guy to knock it down to 3 cents a piece if you buy a lot. This adds to the cost of each "brick" a little, but it is well worth it in my opinion. It's still the cheapest earth block short of an earth tire, and quite managable in size and weight.
The Courses:
Pieces of looped barbed wire and baling wire lengths get laid between each course of earth bags. The barbed wire acts as a kind of velcro to grip the courses and keep them from sliding as the plastic will otherwise do. The baling wire lengths are laid down so that an end extends out past each side of the bag to the interior and exterior of the structure. This is in preparation to receive stucco netting which will support the coats of adobe or other plaster. If you can manage to connect some of the baling wire to the rebar ties being used to seal the ends of the bags, all the better.
It is very important to get a protective coat of mud onto polypropylene earthbags as soon as possible, especially if the sun in your area is strong. Without protection, the bags will begin to deteriorate in a little over 1 season, and you could have quite a problem on your hands. I opted to apply a few initial coats of adobe plaster with just a little portland added for stabilization, to be finished off eventually with a few coats of lime plaster, since I have been very impressed with its properties so far.
A piece of 2x12 was laid down under 1 side of the courses as a way to fasten the door frame. Wooden blocks were embedded intermittently into the courses on the way up to further stabilize the frame. Additionally, a frame for a modest window was accommodated on the south side to help warm up the space a little in winter. Metal lathe was attached to the wood frames of both the window and door prior to installation. The metal lathe was then curled back onto the structure and fastened along with the stucco netting. This helps to prevent cracking along these stress points.
The Bond Beam:
Once the courses were as high as I wanted, pressure-treated 2x12's were laid on top and connected to each other with strong braces. The longest planks were laid down the full length of the structure, so that the connectors could run across the seams in the same direction of the stress that might be created by the quonset style root I had planned. The door buck actually peaked a little above the bond beam, and was strongly attached to the beam on either side with long heavy connectors. The stucco netting was continued over the top of the beam from both outside and inside the structure for extra security. Then, holes were drilled into the beam to receive 4 foot lengths of 1/2 rebar to which the arcs would be attached.
The Quonset Roof:
Rebar (3/8 inch) was arched across the space from east to west in a quonset style. I purchased a rather expensive but pleasant tool designed to bend rebar in very concentrated areas. It was simply a heavy metal bar (not pictured here) with three prongs arranged in an equilateral triangle entending out perpendicular to the length of the handle. It proved indispensible in getting the shape I wanted, and will likely come in quite handy for many future applications.
Heavy stucco netting and metal lath were connected to the quonset arcs using the rebar ties and twister, in preparation for a cement shell.
The Rain Gutters:
I encountered sort of a challenge when I got to the rain gutters, which I hadn't really considered through to the end. The only gutters available at the local hardware stores were the cheapo entensible ones with caps and connectors. I was really hoping to use this structure to increase my rain catchment, but now I am confronting the problem of how to make rain gutters that won't leak. Since my intention is to use lime plaster to protect the building, the gutters really have to be water tight or I am going to have a heck of a mess! Stay tuned as the drama intensifies...
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related images (click to view photos in full resolution)
Time Warp 2: The earth hut gets a hood.
Time Warp 2: The earth hut gets a hood.
My suite of earth-bagging tools. My suite of earth-bagging tools.
A leather punch will penetrate quite a few earthbags in prep for rebar ties. A leather punch will penetrate quite a few earthbags in prep for rebar ties.
The simple rebar tie twister seals up earthbags with a few turns of the wrist. The simple rebar tie twister seals up earthbags with a few turns of the wrist.
You can connect the baling wire to the rebar ties for extra stability. You can connect the baling wire to the rebar ties for extra stability.
Barbed wire looped around on itself acts as velcro to adhere the slippery plastic bag courses to each other. Barbed wire looped around on itself acts as velcro to adhere the slippery plastic bag courses to each other.
The process of building up the earthbag walls. The process of building up the earthbag walls.
The powershed with mud coating and quonset style arches for the roof. The powershed with mud coating and quonset style arches for the roof.
A view of the powershed with gutters connected. A view of the powershed with gutters connected.
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