Editing Building material (section)

====Wet-laid clay walls====
{{Main|rammed earth|sod|cob (building)}}
Wet-laid, or damp, walls are made by using the mud or clay mixture directly without forming blocks and drying them first. The amount of and type of each material in the mixture used leads to different styles of buildings. The deciding factor is usually connected with the quality of the [[soil]] being used. Larger amounts of [[clay]] are usually employed in building with ''cob'', while low-clay soil is usually associated with ''[[sod house]]'' or ''[[sod roof]]'' construction. The other main ingredients include more or less [[sand]]/[[gravel]] and [[straw]]/grasses. ''Rammed earth'' is both an old and newer take on creating walls, once made by compacting clay soils between planks by hand; nowadays [[formwork|forms]] and [[machine|mechanical]] [[pneumatic]] compressors are used.<ref name="Graham">{{cite book |last1=McHenry |first1=Paul Graham |title=Adobe and Rammed Earth Buildings: Design and Construction |date=1984 |publisher=Wiley |isbn=978-0-471-87677-9 |page=104 }}</ref>

Soil, and especially clay, provides good [[thermal mass]]; it is very good at keeping temperatures at a constant level. Homes built with earth tend to be naturally cool in the summer heat and warm in cold weather. Clay holds heat or cold, releasing it over a period of time like stone. Earthen walls change temperature slowly, so artificially raising or lowering the temperature can use more resources than in say a wood built house, but the heat/coolness stays longer.<ref name="Graham" />

People building with mostly dirt and clay, such as cob, sod, and adobe, created homes that have been built for centuries in western and northern Europe, Asia, as well as the rest of the world, and continue to be built, though on a smaller scale. Some of these buildings have remained habitable for hundreds of years.<ref>{{cite book |last1=Smith |first1=Michael G. |chapter=Cob Building, Ancient and Modern |pages=132–133 |editor1-last=Kennedy |editor1-first=Joseph F. |editor2-last=Wanek |editor2-first=Catherine |editor3-last=Smith |editor3-first=Michael G. |title=The Art of Natural Building: Design, Construction, Resources |date=2002 |publisher=New Society Publishers |isbn=978-0-86571-433-5 }}</ref><ref>[https://web.archive.org/web/20100416132054/http://www.takungpao.com/news/10/01/28/_IN-1208245.htm] Earliest Chinese building brick appeared in Xi'an (中國最早磚類建材在西安現身)]. takungpao.com (2010-1-28)</ref>