Papercrete, also called fibrous cement, is a remarkable building material made with recycled paper/cardboard, sand, and Portland cement.
You mix the dry ingredients together with water to make a slurry. This slurry dries into hard blocks that are strong (260 psi compressive strength), lightweight, and an excellent insulator (R 2 per inch). Papercrete holds its shape even when wet. Except for the cement, all the ingredients are free or almost free, which makes papercrete a very inexpensive building material.
Although there are people who are building papercrete/paper adobe structures in the $1.00 a square foot range, a more realistic price is $5 - $10 a square foot. It all depends on how many of the materials (lumber, windows, etc.) you can scrounge. But no matter how you do it, building with papercrete/paper adobe is very inexpensive.
Paper houses make sense. Our landfills are clogged with "waste" paper and cardboard. Millions of people live in substandard housing, or have no housing at all. With papercrete/paper adobe, we can solve both of these problems at once. Rather than throwing "waste" paper and cardboard into landfills, we can turn it into a valuable building material. This is a golden opportunity for us to start managing our solid waste "problem" with a little common sense.
For more information on papercrete, click here to read the introduction to our book. This site also contains many photographs illustrating some of the dozens of papercrete houses that have already been built, and some of the hundreds of experimenters who are working with papercrete today.