A natural building technique called cob is emerging as an alternative home construction method in developing countries. Cob building has many advantages, including more readily available materials, less environmental impact and decreased expenses.
Building with cob involves mixing sand or clay with local subsoil and straw. This creates a stiff substance that can be molded and smashed together into small loaves (cobs). These cobs are then stacked to form the walls and foundations of buildings.
The practice of cob building has its roots in historic techniques, such as adobe and wattle-and daub construction.
“A sculptural technique, which lends itself to curved organic shapes, cob requires minimal tools and can be built by young and old alike,” according to Joseph F. Kennedy of the National Buildings Colloquium.
Unfortunately, cob is very labor intensive and building walls can take up to a year to complete.
However, cob structures are incredibly sturdy and able to withstand a wide variety of climatic conditions, including fires and earthquakes.
Cob can absorb large amounts of water without softening, and it is naturally insulated so it will stay cool in the summer and warm in the winter.
Cob buildings in the British Isles have withstood centuries of harsh weather and still remain in use today. Five hundred year old cob houses in England have recently been discovered in near perfect condition.
Cob is also preferable to other commercially available materials. Brick and concrete blocks are often too expensive for developing countries, while the materials needed to make cob are all locally available.
Additionally, the U.S. Environmental Protection Agency reports that the production of concrete is the third largest source of greenhouse gas pollution in the United States. Making one ton of cement results in the emission of roughly one ton of carbon dioxide.
Cob homes are the cost-effective, environmentally friendly alternative to concrete structures.
Cob buildings are currently going through code-testing procedures in the U.S., and have experienced a major revival in England, where homebuilders are turning to cob as a natural, sustainable construction strategy.
Natural methods of building also have a growing future in humanitarian aid efforts abroad. At the U.N. Habitat II conference in Istanbul, volunteers and local labor built a domed prototype house from compressed earth blocks in a week.
Buildings constructed with this natural, cost-effective and environmentally friendly technique could be the future for aid efforts that provide shelter for those in need.
– Grace Flaherty