Craigslist is my best friend! For the cabin I am attempting to either build or purchase second-hand all of our necessary materials. Again this is making our cabin not only cost efficient but also environmentally sound. It is amazing how many serviceable and good quality items are replaced by homeowners and builders. The saddest part is that these items are often not replaced for lack of functionality but rather for aesthetics. And the aesthetics could conceivably be achieved with just a little elbow grease. The following list details the items that I have already purchased and the price I paid for each:

• 20 small double-hung, double-paned, vinyl windows: $10 each. These windows were picked up from a window dealer as models yet they are fully functional. (There may be a trade off in efficiency versus more modern windows, yet the small size and the other thermal properties of the building help to offset this.)
• 1 Steel Exterior Door: $50.  This door was replaced after a few years of use with a fancier design. It came prehung and predrilled. At this point it needs a coat of paint and a knob/lockset.
• 175 feet of flexible drain pipe: $50. This pipe will be used to construct a french drain at the foundation of our cabin. We needed 150 feet approximately but it is always good to have a little extra. This was purchased from a landscaper that had some left over from a job. New price is usually $1 a foot.
• Bathroom Sink, Base Cabinet, Mirrored Medicine Cabinet: $30. Completely functional and well maintained set. This was purchased from a person "flipping" a house and upgrading the kitchen and bath. It is tiny but perfect for the tiny bathroom that we have planned.

An inherent quality of building with earth is the tendancy of the material to resist rapid changes in temperature. Cold earth wants to stay cold while warm earth wants to stay warm. It takes a great deal of energy to force the temperature shift in one direction or another. However, once you have, it will stay that way for quite some time. This can be both a benefit and a curse depending on the prevailing climate.

Our cabin will be mainly used in the spring and summer but there will be times that we need it during the colder months. In the mountains of Pennsylvania this cold can be quite extreme. In an uninsulated earth cabin we would be faced with a constant need to burn fuel for heat as our interior temperatures attempted to win out over the prevailing exterior temperatures. Two solutions are possible for this problem. The first involves filling the bags themselves with insulation such as scoria, vermiculite, rice hulls, etc. The second involves insulating the outside of the earth structure. Thereby seperating the two temperature extremes and allowing the walls to retain their heat longer. There is a great blog post and related instructable created by Dr. Owen Geiger on this process.

We will be using the exterior insulation method since scoria (lava rock) is rather expensive here in PA and lightweight insulators like perlite would require a wooden frame of some sort. Our unique insulation will be mainly built out of plastic "trash". Specifically, massive amounts of plastic drink bottles and plastic shopping bags are the prime materials. The basic process is outlined below:

1. Stuff a 16 - 20 oz. plastic bottle full with plastic bags (usually 3-4) and screw the cap back on.
2. 20-25 of these stuffed bottles are squeezed tightly into a form. I use a milk crate-style container with the bottom cut out.
3. Squeeze small amounts of expanding spray foam in between the gaps of the bottles. If you have compacted the bottles enough in the form this doesn't take much. Also I use the Great Stuff Big Gap Expanding Foam which really fills the space well.
4. Allow the foam to finish expanding and setting and then remove the "brick" from the form. See the photo below.
5. These bricks can then be mortared together with a natural soil based mortar.

The plastic bricks will be attached to the walls with nylon twine and covered over with plaster. This design reuses thousands of bottles and bags and I hope that it will do an adequate job insulating the walls. The entire job is a lot of work! Collecting the materials alone is a huge job. Luckily for me I am a school teacher and everyone (faculty, students, and the families) at two of our district schools is being such a help and support. I even have my eco-conscious students voluntarily giving up recess to help me stuff bottles full. Certainly without this help I would never be able to do it.