Glossary of Terms

  • Additives
    substances added to a soil to improve its characteristics

  • Adobe
    an earthen building technology: blocks or bricks are formed by pouring a proper mix of soil, water, and straw into molds and drying them in the sun.

  • Cob
    an earthen building technology: moist clayey soil and straw are mixed to form lumps (cobs) and applied directly onto the wall without mortar or framework.

  • Compressed earth blocks (CEB)
    an earthen building technology: blocks are formed by mechanically compressing a proper mix of moist clayey soil into blocks.

  • Earth or Soil
    for building purposes, it is the sub-soil found directly under the top layer of humus or topsoil. It is a mixture of gravel, sand, silt, and clay.

  • Earthen structure
    a structure made largely from a proper mix of soil.

  • Embodied energy
    energy required during the lifecycle of a building material or building — raw materials extraction, transport, processing, manufacturing, delivery, construction, maintenance and repair, and disposal or recycling/reuse. Embodied energy does not include operational energy. The construction industry has only recently started analyzing ways to reduce the embodied energy of materials and buildings.

  • Hygroscopic
    the ability of materials to absorb or adsorb and retain moisture from the surrounding air.

  • Hygrothermal
    the ability of materials to absorb and release water vapor and heat from and to the surrounding air. The presence of clay in earthen walls is responsible for the daily modulation of water vapor and heat, contributing to indoor air quality and comfort.

  • Light clay straw
    an earthen building technology: loose straw is tossed with clay slip and then lightly packed into formwork. It is used as infill in a post and beam structure and is usually coated with lime or earthen plaster. Because the clay and straw mix is primarily straw and not tamped into forms nearly as forcibly as rammed earth, light clay straw walls are a fraction of the density of rammed earth walls and not load bearing.

  • Monolithic
    construction where walls are built of a single material, such as rammed earth and cob.

  • Operational energy
    the energy consumed when a building is used. Until recently, the construction industry focused only on making building materials and buildings more energy efficient to operate.  See the definition of embodied energy above.

  • Plaster
    a soft mixture of clayey soil, water, sand, and lime that is spread on walls and ceilings to give a smooth or textured, hard surface finish. In modern times, lime plaster has been replaced by gypsum plaster, although lime can still be used. In addition, fibers sometimes are added for additional strength.  Cement is sometimes added or replaces lime for more durability but reduces the breathability of the walls. Traditionally, the term plaster refers to the material used on interior surfaces while stucco is the term used for exterior surfaces, but people often interchange the terms for either interior or exterior.

  • Rammed earth
    an earthen building technology:  a proper mix of moist soil placed in wide formwork and mechanically compressed, resulting in a monolithic wall which may be load bearing. Stabilization material is commonly added to the mix when exposure of the soil layers is desired.

  • Slurry or slip
    clayey soil is mixed with water. Slurry is a thick mixture and slip is a thinned mixture.

  • Stabilized Earth
    earthen construction (blocks or monolithic) that uses a binder such as lime or cement for compressive strength and durability.

  • Stucco
    traditionally, a mixture of lime, sand, and water for application, it dries to a hard, durable, smooth or textured finish. Refer to the definition of plaster as people use the terms interchangeably.

  • Vapor permeability
    the ability of building materials to continually absorb and release water vapor.

  • Wattle and Daub
    an earthen building technology: a mix of earth and straw is applied into an interwoven lattice of wooden strips and smoothed over.