Cob (material)
Cob, cobb, or clom (in Wales) is a natural
In technical building and engineering documents, such as the Uniform Building Code of the western USA, cob may be referred to as "unburned clay masonry," when used in a structural context. It may also be referred to as "aggregate" in non-structural contexts, such as "clay and sand aggregate," or more simply "organic aggregate," such as where cob is a filler between post and beam construction.
History and usage
Cob is an English term attested to around the year 1600[3] for an ancient building material that has been used for building since prehistoric times. The use of this material in Iran is more than 4000 years old. The etymology of cob and cobbing is unclear, but in several senses means to beat or strike,[4] which is how cob material is applied to a wall.
Many similar materials and methods of earthen building are used around the world, such as
Cob structures can be found in a variety of climates across the globe. European examples include:
- in England, notably in the counties of Devon and Cornwall in the West Country,[9] and in East Anglia (where it is referred to as clay lump)[10]
- in Wales, notably in rural Anglesey[11]
- in Donegal Bay in Ulster and in Munster, South-West Ireland[citation needed]
- in Finisterre and Ille-et-Vilaine in Brittany, where many homes have survived over 500 years and are still inhabited[citation needed]
Some of the oldest human-made structures in Afghanistan are composed of rammed earth and cob.[12] Cobwork (tabya) was used in the Maghreb and al-Andalus in the 11th and 12th centuries, and was described in detail by Ibn Khaldun in the 14th century.[13]
Many old cob buildings can be found in Africa, the Middle East, and the southwestern United States like the Taos Pueblo.[citation needed] A number of cob cottages survive from mid-19th-century New Zealand.[14]
Traditionally, English cob was made by mixing the clay-based subsoil with sand, straw and water using
The walls of a cob house are generally about 24 inches (61 cm) thick, and windows were correspondingly deep-set, giving the homes a characteristic internal appearance. The thick walls provided excellent thermal mass which was easy to keep warm in winter and cool in summer.[9] Walls with a high thermal mass value act as a thermal buffer inside the home.[16] The material has a long life-span even in rainy or humid climates, provided a tall foundation and large roof overhang are present.[9]
Cob is
Modern cob buildings
In 2000-01, a modern, four bedroom cob house in
In the Pacific Northwest of the United States there has been a resurgence of cob construction, both as an alternative building practice and one desired for its form, function, and cost effectiveness. Pat Hennebery, Tracy Calvert, Elke Cole, and the Cobworks workshops erected more than ten cob houses in the Southern Gulf Islands of British Columbia, Canada.[citation needed]
In 2010, Sota Construction Services in
In 2007, Ann and Gord Baird began constructing a two-storey cob house in
Welsh architect Ianto Evans and researcher Linda Smiley refined the construction technique known as "Oregon Cob" in the 1980s and 1990s. Oregon Cob integrates the variation of wall layup technique which uses loaves of mud mixed with sand and straw with a rounded architectural stylism.[24][25] They are experimenting with a mixture of cob and straw bale denominated "balecob".
Cob building code
In 2019 an appendix for the International Residential Code (IRC) was approved by a vote in the public comment hearings.[26] Appendix U of the IRC governs use of cob in load-bearing walls of single story residential structures. Based on currently available test data, the appendix limits the conditions under which cob may be used without engineering approval, such as seismic activity.
See also
- Adobe – Building material of earth and organic materials
- Appropriate technology – Technological movement
- ARGE-SH, a German Research-Institute for Cob-buildings
- Chirpici– Earth blocks for construction (a variant of cob used in southern Romania)
- Composite material – Material made from a combination of two or more unlike substances, the earliest human-made composite materials were straw, combined with mud, to make bricks and walls.
- Compressed earth block – Building material
- Earth structure – Building or other structure made largely from soil
- Earthbag construction – Building method
- LOHAS – Demographic defining a particular market segment
- Mudbrick – Earth blocks for construction
- Rammed earth – Construction material of damp subsoil
- Rice-hull bagwall construction
- Sod – Upper layer of soil and grass
- Sod house – Turf house used in early colonial North America
- Straw-bale construction – Building method that uses bales of straw
- Superadobe – Form of earthbag construction
- Vernacular architecture – Architecture based on local needs, materials, traditions
- Woodway House – Historic house in Devon, England, a typical Devon cob building
References
- ^ Wright, Joseph. "COB(B, sb3. 1.", The English Dialect Dictionary, Being the Complete Vocabulary of All Dialect Words Still in Use, or Known to Have Been in Use during the Last Two Hundred Years. London: H. Frowde;, 1898. 676-677. Print.
- ^ Goodnow, Cecelia (October 5, 2007). "Thinking of building a cob home?". Seattle Post-Intelligencer.
- ^ "cob, n2. 1." Oxford English Dictionary 2nd. ed. 2009. CD-rom.
- ^ "cob". Collins English Dictionary. HarperCollins. Retrieved 13 January 2017.
verb: (transitive) British informal to beat, esp on the buttocks
- ^ a b c d e Rapp, George Robert. "Unbaked clay or mud", Archaeomineralogy. 2nd ed. Berlin: Springer, 2009. Print.
- ^ Oliver, Paul; Hess, Janet B. (23 February 2012). "African architecture". Encyclopædia Britannica. Retrieved 13 January 2017.
- ^ a b c Edwards, Jay Dearborn, and Nicolas Verton. "mud with straw", A Creole Lexicon Architecture, Landscape, People. Baton Rouge: Louisiana State UP, 2004. Print.
- ^ "cat and clay" Websters Online Dictionary accessed March 23, 2015.
- ^ a b c Gunawardena, K., 2008. The future of cob and strawbale construction in the UK. Bath: University of Bath.
- ^ Bouwens, Dirk. "Earth Buildings and Their Repair". buildingconservation.com. Cathedral Publications Ltd. Retrieved 13 January 2017. [reproduced from The Building Conservation Directory, 1997]
- ISBN 9781786832856.
- ^ McArdle, Patricia (June 19, 2011). "Afghanistan's Last Locavores". The New York Times.
- ISBN 0-415-02063-8.
- ^ Dozens of cob cottages are listed on the Register of the New Zealand Historic Places Trust, e.g. "Ferrymead Cob Cottage". Rarangi Taonga: the Register of Historic Places, Historic Areas, Wahi Tapu and Wahi Tapu Areas. New Zealand Historic Places Trust Pouhere Taonga. Retrieved 21 August 2013.
- ISBN 978-1-60059-534-9. Retrieved 1 June 2013.
- doi:10.1016/j.enbuild.2004.08.005. Archived from the original(PDF) on 10 January 2015. Retrieved 24 January 2013.
- ProQuest 1856858074– via ProQuest.
- The Institution of Structural Engineers: 111–15.
- ^ Practical Sustainability: About
- ^ Welcome to The Hollies (2010-08-03). "The Hollies". thehollies.ie. Retrieved 2010-12-04.
- ^ "Sota Construction Services, Inc. - Sota Construction Corporate Offices". Archived from the original on 2013-10-17. Retrieved 2013-11-28.
- ^ "Sota Construction Office Expansion | U.S. Green Building Council".
- ^ Barton, Adriana (3 August 2007). "A Dream Home Made of Mud". The Globe and Mail. Retrieved 2008-09-26.
- ^ The History of Cob
- ^ Building with Oregon Cob
- ^ Cob code appendix approved for the 2021 IRC
Further reading
- Building With Cob, A Step by Step Guide by Adam Weismann and Katy Bryce. Published by Green Books ; 2006, ISBN 1-903998-72-7.
- The Hand-Sculpted House: A Philosophical and Practical Guide to Building a Cob Cottage (The Real Goods Solar Living Book) by Ianto Evans, Michael G. Smith, Linda Smiley, Deanne Bednar (Illustrator), Chelsea Green Publishing Company; (June 2002), ISBN 1-890132-34-9.
- The Cob Builders Handbook: You Can Hand-Sculpt Your Own Home by Becky Bee, Groundworks, 1997 ISBN 978-0-9659082-0-7
- Essential Cob Construction: A Guide to Design, Engineering, and Building by Anthony Dente PE, Michael Smith, and Massey Burke, New Publishers Society; 2024, ISBN 978-0865719682.