The article discusses the issue of sustainable buildings. Now people can live in a paper house that is so strong even stones would not make a dent. Researchers Kate Thayer and Clyde Curry of Marathon, Texas tell several advantages of building with recycled paper. For the past four years they have been testing and building with various forms of papercrete, manageable-sized bricks made of recycled paper products and Portland cement. With readily available raw materials and short construction times, interest is growing in the concept of turning trash paper and cardboard into inexpensive houses that are strong, well insulated and easily built. Papercrete provides strength without the weight of concrete, making it an ideal material for building arches, domes and vaulted ceilings. Construction costs with papercrete are estimated at 20 to 30 percent less than conventional housing. Scan Sands built his ecologically responsible home in Columbus, New Mexico with $500 in materials. Papercrete structures also require only 50 percent of the energy needed to heat and cool conventional buildings.