The construction industry is a multi-billion Rand industry, and the production and harvesting of raw materials for building purposes occurs on a world-wide scale. The environmental performance of the construction industry is coming under close scrutiny, particularly with regard to the availability and sustainability of certain materials, and the extraction of the large quantities needed.

Building material is any material used for construction. Many of these materials are sourced from natural-occurring substances such as clay, sand, wood and rocks. Building materials typically considered to be green include rapidly renewable plant materials like bamboo (it grows fast) and straw, timber from forests that are managed sustainably, and other products that are non-toxic, reusable, renewable, or recyclable.

Natural materials
The CSIR’s Llewellyn van Wyk gives us some insight into natural building materials, which are unprocessed or require minimal processing, such as timber or grass.

• Mud and clay
  The amount of mud and clay used leads to different construction approaches to building, with the quality of the soil used being the determining factor. Ingredients added to mud and clay generally include sand and gravel, and straw and grass.
  
  Mud and clay are good thermal mass materials and maintain temperatures at a constant level. Clay holds heat or cold, releasing it over a period of time, much like stone. Earthen walls will thus require more heat to warm up, but will retain the heat or coolness longer.
  
  
• Stone
  Stone has been used as a building material from the earliest times as it is generally readily available and extremely long lasting. Some ancient civilizations  known for their stone buildings are the Egyptians, Aztecs and Incas.
  
  As stone is a very dense material, it requires intensive heating to become warm. Rocks were generally stacked dry but mud, and later cement, can be used as a mortar to hold the rocks together.
  
  
• Thatch
  Thatch is also one of the oldest materials used in construction, especially in Africa. Grass is a good insulator and easily harvested, making it one of the truly renewable materials that can be used in buildings.
  
  
• Wood
  Wood is a generic building material used for just about any structure in most climates. Wood is a product of fibrous plants and trees and is used as a construction material when cut or pressed into timber such as boards, planks and similar materials. Wood is also a truly renewable material, although the rate of harvesting is threatening the continued existence of certain species.
  
  Historically, wood for building structures was used as unprocessed logs, cut to the required length and notched into place. The development of mechanised tools enabled logs to be cut into varying dimensions, resulting in easier and quicker construction.
  
  Other woodworking techniques, such as the gluing of strips of wood, yield even stronger timber sections (laminated beams and boards); the compression of wood dust and chips with a binding agent (glue) produces compressed boards of greater strength and in greater lengths and widths than would otherwise be possible.