Earth Building

Mudbrick, also referred to by the Spanish name of 'Adobe' which means mud or puddled earth, generally refers to the technique of building with sun-dried mud blocks in either load bearing or non load bearing construction. Mudbricks are becoming increasingly commercially available in a range of stabilised and non stabilised bricks.

Mudbrick has several advantages over conventional fired clay or concrete masonry. The advantages include:

• Low in embodied energy
• Utilisation of natural resources and minimal use of manufactured products
• Good sound absorption characteristics
• High thermal mass
• A claimed ability to "breath"
• Suited to a wide range of soils
• Easily manufactured and worked
• Flexibility in design/colour/surface finishes
• Insulation properties similar to those of concrete or brickwork

Mudbricks are typically 250 mm wide x 125 mm high x 375 mm long and normally made from earth with a clay content of 50 to 80% with the remainder comprising a grading of sand, silt or gravel. Kaolin clays are the preferred clay types due to their non expansion characteristics. Stabilising the mudbrick with straw or other fibres is sometimes employed where the soil mix displays excessive shrinkage behaviour. Cement and bitumen stabilising is also used with the latter particularly effective in waterproofing.

From an engineering viewpoint, mudbricks typically have compressive strengths of around 1 to 2 MPa and need to posses a demonstrated resistance to erosion and cracking before being accepted for construction. Mortar for mudbrick laying is either a traditional sand/cement mortar or a fine aggregate soil mortar preferably made from the same parent material as the mudbrick units.

Finishing of mudbrick walls can be undertaken with a variety of techniques ranging from as constructed to a simple "bagged" finish to a full set earth render. Linseed oil is commonly used to seal the exterior of as constructed mudbrick.