Materials For Natural Building
The materials common to many types of natural building are clay and sand. When mixed with water and, usually, straw or another fiber, the mixture may form cob or adobe (clay blocks). Other materials commonly used in natural building are: earth (as rammed earth or earth bag), wood (cordwood or timber frame/post-and-beam), straw, rice-hulls, bamboo and rock.
A wide variety of reused or recycled materials are common in natural building, including urbanite (salvaged chunks of used concrete), tires, tire bales, discarded bottles and other recycled glass. Several other materials are increasingly avoided by many practitioners of this building approach, due to their major negative environmental or health impacts.
These include unsustainably harvested wood, toxic wood-preservatives, portland cement-based mixes, paints and other coatings that off-gas volatile organic compounds (VOCs), and some plastics, particularly polyvinyl chloride (PVC or “vinyl”) and those containing harmful plasticizers or hormone-mimicking formulations.