Numerous cob buildings found in Devon and Cornwall are well over 500 years old.
Locally Tuinhuis at the houses of parliament in Cape Town is over 300 years old.
No complicated machines or tools are required, simply lots of labour and only very basic skills.
This material is a very durable form of earth construction.
Cob has higher tensile strength than other types of earth construction, which in general is weak in tension.
Offering relatively good levels of thermal comfort with a high level of thermal mass and humidity exchange.
Mixing and building with cob is very simple and easy to work with.
It requires no specialist tools.
Is well suited to community participation.
Materials can often be sourced from the site itself saving on transport costs.
It is also extremely versatile due to its sculptural qualities and is often used in combination with other natural building methods, like straw bale and sand bag wattle and daub etc.
A mixture of clay, straw and sand is mixed together into a stiff consistency and packed directly onto a masonry plinth wall.
The straw acts as reinforcing and while the compacted earth and sand mix create the compressive strength.
While cob can be mixed manually this process is very slow. Various forms of mechanization can be employed to greatly speed up the mixing process.
The walls need to dry sufficiently as they are built to avoid slumping, so generally one can only built about 300mm a day.
Company Track record and examples of work:
House Ashmole - 2009-2010, Stellenbosch
House Perry - Masepumalela informal settlement, Kommetjie, Cape Peninsular, 2007
House Brodie - Scarbourgh, 2003
Community Edu-care for Flower Valley Conservation Trust - Gansbaai, Western Cape, 2002
Note that all straw bale projects undertaken 1998 – 2013, have incorporated elements of cob construction