The drive is on to build homes using fewer so-called virgin materials, and builders earn points for green building when they select materials that have been used before. While it's difficult, if not impossible, to build to code using only recycled materials, many recycled items are finding their way into every stage of construction. Take this quiz to see how certain items become building materials: by being renewed, reused or recycled?
Steel manufacturers are harvesting scrap metal from factories and recycling it to reduce the cost of steel beams. A leading trade association says recycled steel beam construction is undercutting the cost of wood-frame buildings.
Typically, rigid foam has been highly toxic. A San Diego surfboard maker has started manufacturing a new form of foam from kelp and hemp, using renewable materials.
Grain production in the United States creates about 200 million tons of straw per year. The National Association of Home Builders cites recycling this straw into bales as an inexpensive, well-insulating and effective way to create building material.
Lumber manufactured from recycled wood fibers and plastic bags is gaining popularity for use in building decks and playgrounds.
The hobbyists who build walls out of beer bottles are pretty well known. More recently, an architect from South America has added a twist by filling plastic soda bottles and reusing them to boost the structure of walls for shelters in third-world countries and disaster zones.
Many carpets are now manufactured from recycled plastic soda bottles. One manufacturer says that 1 square yard (0.8 square meter) of carpet keeps 40 plastic bottles out of the landfills.
It turns out that parts of old cars can be worth more than you might think: Flooring manufacturers can make tile out of recycled car windshields.
Adobe and rammed earth, though complicated to use as building materials, are viewed as the ultimate renewable materials.