Earth wall construction issues
Earth building has been around for 11,000 years and is used worldwide. The common feature in all earth building techniques is that the earth material is subsoil that is composed of clay, silt, and sand where clay is the binder or cementing ingredient and the drying process is through the evaporative effect of sun drying.
Earth building uses unfired earth material to construct:
Methods of earth building
There are at least 12 methods of earth building used and these can be further divided into a total of 18 techniques.
Two of the best known methods are earth brick (mud brick) and rammed earth.
Earth brick (mud brick)
Mud brick is the most popular name used in Australia to describe bricks made from various compositions of soil that are dried at air temperature during brick production.
There are many ways of making mud brick. One major distinction however is the consistency and water content of the material at the time of forming into bricks. With puddled mud bricks, the moisture content is high and the texture is that of mud or dough. With pressed mud bricks the moisture content is lower and the consistency is that of damp soil.
Rammed earth is damp or moist earth, with or without any additive, that is rammed in place between a temporary moveable formwork. It is a solid masonry wall that does not have, and does not need any cavity.
Issues with earth wall construction and how these buildings are assessed
Gaining building rules consent for a building that uses earth wall construction may not be as straightforward as one using one of the more common construction methods.
While there has previously been references to earth wall construction (The CSIRO Bulletin 5, 1987, Earth–wall Construction) in the Building Code of Australia it was removed in 2008 as the CSIRO document was obsolete and no longer available.
A replacement document is being developed by the Earth Building Association of Australia, but it is not yet suitable for use in the Building Code. Therefore, for an earth wall construction to be issued building rules consent the applicant will need to reference other technical design sources or seek the advice of a structural engineer.