If you’re looking to build a sculptural fantasy home, cob is for you. With cob, any shape, flourish, and feature can be accomplished to create something unique and artistic.
The History of Cob
Cob houses have been standing for centuries. The concept of living in a mud hut has probably been around since the dawn of Man.
The word cob comes from the Old English meaning, “a lump or rounded mass.” The technique has been in use for hundreds of years throughout Europe, where the thick walls can keep you warm and dry. Cob was especially popular in England, with roots going back to at least the 13th century. The scarcity of stone and wood made using the abundant sandy clay soil perfect for cob construction.
By the 15th century, cob houses became the standard method of construction in England — that is, until the industrialized methods of brick and lumber took over around 1880.
What Cob Is
Cob construction is just like a ceramic sculpture — a really large one. A mixture of clay, sand, straw, water, and earth, cob is very similar to adobe in raw material. Instead of being formed into bricks, cob is built up a handful at a time. The strong, fireproof walls can create artistic and sculptural earthquake-resistant walls. Requiring little money or skill, a cob home can be built by homeowners willing to get their hands dirty.
Before you start thinking it’s like living in a mud patty, keep in mind that the finished cob wall is covered with plaster, similar to adobe. Where adobe uses same-size bricks to create flat walls, cob lends itself to organic shapes, including arches, vaults, and curves.
Cob walls contain no steel reinforcing or cement, so they’re typically sculpted to be 1 to 2 feet thick for stability. The thick walls create a cozy and surprisingly dry home.
The process of using cob is simple to learn. Cob is also cheap to build with. No bricks, forms, or wood are needed.
Cob construction uses sand, clay, and long strands of straw. Cob walls are built over a standard foundation by applying layer after layer of this mixture. These layers (called cobs) are placed by hand and then stepped on to pack it into place. Each layer must be dry before the next one can be applied. The walls rise slowly depending on how long the drying takes. Anywhere from 6 inches to 3 feet of wall may be completed in a day, but then it needs to be left alone for up to two weeks to dry completely. To reduce the weight, the walls taper and get thinner as you build up, from 24 inches at the bottom to 12 inches at the top. As they dry, the walls are trimmed and shaped to keep them straight.
Doors and window openings are simply set into the wall as it takes shape. ....read more
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