Light clay is a natural building material used to infill between a wooden frame in a timber framed

Timber framing

Timber framing , or half-timbering, also called in North America "post-and-beam" construction, is the method of creating structures using heavy squared off and carefully fitted and joined timbers with joints secured by large wooden pegs . It is commonplace in large barns...

 building using a combination of clay

Clay

Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

 and straw

Straw

Straw is an agricultural by-product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has many uses, including fuel, livestock bedding and fodder, thatching and...

, woodchips

Woodchips

Woodchips are a medium-sized solid material made by cutting, or chipping, larger pieces of wood. Woodchips may be used as a biomass solid fuel. They may also be used as an organic mulch in gardening, landscaping, restoration ecology and mushroom cultivation...

 or some other lighter material.

History

A mixture of clay and straw was used as an infill material for timber framed

Timber framing

Timber framing , or half-timbering, also called in North America "post-and-beam" construction, is the method of creating structures using heavy squared off and carefully fitted and joined timbers with joints secured by large wooden pegs . It is commonplace in large barns...

 building from at least the 12th century in Germany and elsewhere in Europe. Renewed interest in traditional building methods developed from the 1980s after which various natural building

Natural building

A natural building involves a range of building systems and materials that place major emphasis on sustainability. Ways of achieving sustainability through natural building focus on durability and the use of minimally processed, plentiful or renewable resources, as well as those that, while...

 architects and builders started promoting the use of light clay.

Usage

Local clay, often local subsoil, is mixed into a slurry with water and then combined with straw or wood chip or other similar material. Wood chips can vary in size from sawdust

Sawdust

Sawdust is a by-product of cutting lumber with a saw, composed of fine particles of wood. It can present a hazard in manufacturing industries, especially in terms of its flammability....

 to chip 5cm in diameter. The ratio of clay to other ingredients can be adapted to either increase thermal mass or insulation properties. The mixture is provided with additional structural strength using wattles

Wattle and daub

Wattle and daub is a composite building material used for making walls, in which a woven lattice of wooden strips called wattle is daubed with a sticky material usually made of some combination of wet soil, clay, sand, animal dung and straw...

. When used externally it can be protected with a Lime render

Lime Render

Lime render is a lime-based cementitious mix applied to the external surfaces of traditionally-built stone buildings. It allows the building to 'breathe' - as lime is porous, it allows for the collection and evaporation of moisture...

or a clay render.