What is a cob house
The name ‘cob house’ originated in England during the 13th Century. Though its exact etymology is unknown, it is thought that the term may originate from a word that means to strike. (This is how cob material is applied to walls).
While the name cob house originated in England, houses of this type have been made in various places around the world, including across Europe, China, India, Ukraine, the Middle East, the Sahel and equatorial Africa, the American Southwest, and even in New Zealand for over 10,000 years.
What is a cob house made of
Unlike mud houses, which are made by simply mixing earth and water (as well as maybe straw to reduce cracking in the sun), cob homes are made by mixing clay, sand, and straw. They are extremely durable and are said to be able to last for hundreds (if not thousands) of years. For this reason, as well as the fact that they are sustainable, cob houses are currently experiencing a surge of popularity.
They are becoming increasingly common among environmentally conscious homeowners around the world (including here in Australia). And they aren’t all alike. In terms of foundation and floor plans, they vary from tiny cottages or sheds to the 10,000 square foot cob castle featured in ‘House 4’ below.
The features & benefits of cob houses
1. They are cheap to build
The question of cost or how much to build is always important. The material required to build cob homes is plentiful and generally available right on the block where the house will be built. Therefore, they are very inexpensive to build. In fact, cob houses cost about 10% of the cost of a conventional house.
2. Durable, weatherproof, termite proof, fireproof, and earthquake resistant
Counter-intuitively, cob homes are porous and therefore unaffected by wet weather. They stay dry and don’t degrade when wet. And, because soil is their base material they don’t burn and are unaffected by termites. They are also suitable for earthquake prone locations because they are built as a single monolithic piece, and therefore are not susceptible to cracking when they shake.
3. Energy efficient & sustainable
Made without additives, chemicals, or machinery, cob has a carbon footprint of zero. On top of that, cob houses have very thick walls and a high thermal mass, which means that are good at maintaining a consistent indoor temperature. They keep things cool in hot climates and carry heat well in colder climates, which means they are energy efficient and cut energy bills.
4. Design flexibility & aesthetic appeal
With their natural curves, cob houses have an appealing, cosy feel about them. And, because it is a very flexible building material, it is possible to incorporate unique shapes and design elements into cob homes. The accompanying pictures are testament to this fact.
How do I build a cob house in Australia
The basic recipe for cob is two parts clay, one part sand, a small amount of straw and water. The traditional way to mix these materials is with your feet.
Perhaps the only negative associated with cob houses is the fact that their construction takes a long time to build compared to conventional homes. This is mainly because, once you have made cob you have to wait months (or even years) for it to dry. Then, once it is dried and you add the roof, you need to wait another several months before moving in.
Some beautiful cob houses
1. Goatling cob house
Located in Somerset England, this house owes its spectacular design to its artisan designers, Lisa and Rich. It features clay collected form a nearby stream, as well as pine and hawthorne logs from local woodlands. It also has cedar shingles on the roof and straw bales on its sides.
2. Curvy cob house
Built over a three-year period by an architect and her carpenter husband, this cob house is located in County Sligo, Ireland. Though there is a lot of timber in this house, it features about 80 per cent reclaimed materials. It was finished in 2010.
3. Cadhay cob house
Located in Devon in Southwest England, this 2,500 sq ft home includes four bedrooms, a big living room, a kitchen, a dining room, a second-floor family room and three full-sized bathrooms. It also has underfloor heating, chestnut, and oak windows, locally made ironmongery, green oak beams, and a water reed thatch roof.
4. East Devon cob house
Featured twice on Grand Designs (in 2011 and 2018), this extraordinary cob castle (also in Devon) took seven years to complete. It includes 2000 tonnes of cob and meets the highest environmental standards. Its walls are made with polystyrene and are A+ rated for sustainability, and they are also rendered with lime.
5. Romanian cob house
The work of architect, Ileana Mavrodin this cob house is located in the western part of Romania, on the shore of Nera river, close to the Banat village Sasca Română. The architect is part of a movement that seeks to rediscover local materials and traditional building skills.
6. Brittany cob house
Located in the Brittany region of France, this unique house was completed in 2012. Apart from its fairy-tale design, its most striking feature is the presence of grass on its roof.
7. Malborough cob cottage
Located in Malborough NZ and built in the early 1900s, this cottage is typical of cob house made in the region during that time. Now a tourist attraction, it was originally used as a school.
8. Cob House Australia
This cob house in Victoria features an internal column designed in the shape of a tree trunk, as well as several similar decorative flourishes both upstairs and downstairs.