Straw

• It only took a huff and a puff for the Big Bad Wolf to blow down the Little Pig's straw house -- but he would have a much harder time with a modern straw-bale houses.
  
  Straw-bale houses are typically built around a wooden or steel-beam frame. The walls are filled in with straw bales, which are then covered with adobe mixed with straw.
  
  Straw offers many advantages over traditional building materials: It is cheap, fast to build with, and an excellent insulator.
  
  

Earth

• Plain old dirt is one of mankind's oldest building materials, as the mud-brick buildings of the ancient Egyptians can attest. It is also extremely durable, fireproof, and inexpensive.
  
  Sod houses and houses dug into hillsides were common among the first settlers of the American West, but today the most common earth homes are made of adobe bricks. Adobe is made by mixing water, mud, and straw. It is then formed into bricks and dried in the sun.
  
  Adobe homes have a high thermal mass, meaning they retain heat and cold well. This makes them popular in desert climates -- the Pueblo Indians of the American Southwest have used adobe in their buildings for thousands of years.
  
  

Tires

• Worn-out tires are an environmentalist's nightmare: They are nonbiodegradable, full of toxic chemicals, and usually end up in landfills. That is why Michael Reynolds' "earthship" concept is revolutionary: His homes are built almost entirely of used tires, filled with earth and used like bricks to create environmentally friendly, low-impact homes.
  
  Tire homes, including Reynolds' "earthships," are usually constructed around a wooden frame, which is then filled in with the earth-filled tires. These are then covered with rammed earth and plastered with adobe.
  
  

Paper

• Looking for something to do with all those old magazines? A paper house might be the answer. Papercrete, a mix of paper pulp and cement or clay, is strong, fireproof ,and an excellent insulator. Plus, it is flexible: It can be poured to form bricks or used instead of concrete in combination with other construction materials. Just do not get it wet -- unsealed papercrete, like paper, is extremely absorbant, and nobody wants a soggy home.