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What is cob in building terms?
Cob, also known as cobb, is a building material that comprises subsoil, straw (or another fibrous organic material), water, and occasionally lime. Cob walls are laid in courses, each one being left to completely dry before the next one is laid.
How long do cob houses last?
How long does cob last? The oldest cob house currently standing is 10,00 years old. If this doesn’t speak to how strong and durable cob houses are, then nothing will. Cob houses are built to stand forever as long as their roofs are maintained, and they are properly looked after.
Are cob houses good?
A cob home is one of the most durable types of earth architecture. Because the mud mixture is porous, cob can withstand long periods of rain without weakening. A plaster made of lime and sand may be used to windproof the exterior walls from wind damage.
Are cob houses waterproof?
Cob is very resistant to weathering. Because of its porous nature, it withstands long periods of rain without weakening. However, too much exposure is best avoided by the “boots and cap” strategy: wide roof eaves to protect the walls and an impervious foundation.
Are cob houses well insulated?
Put bluntly, cob is a pathetic insulator. This goes for any earthen building material. But what earthen materials lack in insulation properties they make up for with thermal retention. Cob is also a very poor conductor of heat and has very low thermal conductivity.
How strong is a cob house?
Cob house is extremely durable as the base material for its structure is natural re-bar which gives strength to the building. The eco-friendly home is also earthquake resistant as the whole structure acts as one monolithic piece which doesn’t develop cracks when the earth shakes.
Do cob houses burn?
The clay in the cob helps to take the moisture out of the room if humidity is too high, conversely it provides moisture if air is too dry. Fire-Proof: Earth does not burn. Cob is long lasting, durable and easy to repair: Earthen homes can literally last for thousands of years with proper maintenance.
Can I get a mortgage on a cob house?
Cob houses are generally acceptable to most mortgage companies, but it is worth checking with a financial advisor before making a mortgage application. Like many other older building methods, thatched roofs offer excellent thermal properties, as well as looking particularly attractive on the top of an old cottage.
Do you need planning permission for a cob house?
As with all builds, it is necessary to get planning permission and satisfy Building Regulations. While this may be complicated there is no reason why you should fall short of meeting the Building Regulations, but obtaining planning permission will depend on the outlook of your local planning office.
Are cob houses expensive?
A decent cob house can be built for anything ranging around $4,000 – $10,000. However the cost can vary depending on the climatic condition, location and the size of the house. The basic cost, however, may lie somewhere around $2000 – $5000.
How long does it take to build cob house?
Cob building lends itself to incorporating salvaged and eclectic building materials. This ìhobbit houseî in Wales was built in four months and cost about $4,600 in building materials.
Are cob houses Dusty?
There’s been no change here. It doesn’t dust very much at all, except for one certain shelf in the house, where I simply used too much plaster to even it out.
How long does it take for a cob house to dry?
Cob Houses Are Healthy Once you make your cob, it will need to dry out full and that can take months to years. The bulk of the moisture will dry out of the walls in the first year, but will not fully cure for 1-2 years past that.
How do you protect cob walls?
In cold weather, the work must be protected from frost attack, by using thermal blankets e.g. polystyrene sheets. Hydraulic plasters/mortars will stand up to cold conditions after 3-4 weeks of hardening.
What is the difference between cob and adobe?
How is cob different from adobe? Cob is only one of many methods for building with raw earth, the world’s commonest construction material. The most basic difference is that adobe is formed into rectangular bricks which are dried in the sun before being used, while cob is built wet.
What is the R value of a cob wall?
A: There has been very little engineering testing done on cob per se. Most of the numbers we use were actually derived from studies of adobe, which is similar in its makeup. Purported R values range from a low of 0.3 per inch to a high of 1 per inch.
Can you build a cob house in the winter?
When you think about cob, you need to kind of think about it not having any insulation value at all. So technically, there’s about an R3 insulation value for a foot thick wall of cob. These are just concrete walls and people are fine in these buildings in cold climates. You just need a heat source inside.
How thick do cob walls need to be?
As an experiment, Ianto at Cob Cottage Company has built free-standing walls as little as 2″ thick. However, I would recommend something more in the 6″ to 8″ range, both for ease of construction (very thin walls are harder to keep plumb) and for sound insulation.
