This article is available also in spanish here

Exploring the concept of cob houses: longevity, legality, electricity, and thermal insulation

My list

Author | Lucía Burbano

Although they may look like little houses that belong in a fairy tale or Frodo's house in 'The Lord of the Rings', cob houses recover ancient construction materials to fly the flag for an architectural movement based on bioconstruction and sustainability.

COB: building with clay, sand and straw

The term cob essentially refers to three natural materials used in construction: clay, sand and straw which, once mixed together, produce buildings with interesting features in terms of habitability and cost reduction.

Temperature regulating properties

cob houses 2

This mixture produces thick walls that manage to regulate the interior temperature thanks to their capacity to absorb high and low temperatures. The result is very stable interior room temperatures, without the great fluctuations seen in conventional buildings.


Some cob houses were builthundreds of years agoand are still standing today. Many of them are covered with straw bales half a meter deep or more, which helps them to withstand extreme weather conditions. However, to avoid long-term humidity it is advisable to use lime plaster to cover the exterior and add an extra protective layer.

They are healthy

The materials used are highly breathable, which results in improved, clean and fresh air quality. The only thing that needs to be monitored are the interior humidity levels.

Building a COB house

cob houses 3

Despite the clear DIY nature of COB houses, building one does not just consist of mixing the aforementioned materials. As it is a home, licenses need to be obtained from the local authorities and certain standards need to be followed, which are practically identical to those that apply to normal buildings (drawing up plans, preparing the land, foundations, etc.).

Cob constructions are also monolithic. Instead of the walls being composed of thousands of individual bricks, a cob wall is more like one single giant brick. Summarized, building a cob house involves the following steps:

First, the foundations

cob houses 4a

During this process, concrete or stones can be used to protect the lower part of the structure from potential humidity.

Preparing the cob mixture

To achieve the adobe, mix 2 parts clay soil to 1 part wet sand. Once the desired consistency is reached, add a fine layer of straw to form a ball that does not flatten or stick.

By layers

Using a wooden structure or bamboo canes, start applying the COB mixture from bottom to top, allowing the lower layers to dry first. We recommend building them in spring or summer to avoid environmental moisture.

Examples of cob houses and variations

cob houses 4

Popular in South West of England during the Middle Ages, there are examples all around the world, from the Arabian peninsula, to India, Africa or in Southwestern United States.

Although the classic building style with curved lines in traditional structures is the most well-known (and in fact, numerous buildings can be found in tourist guides in the United Kingdom), and in fact it continues to define the new homes being built following this technique), the architecture of cob houses can also be seen in modern buildings such as the offices of the construction firm Sota Construction Services in Pittsburgh, United States, which combines state-of-the-art technology and a modern design with this traditional technique to achieve an extremely efficient building.

Lastly, there are other variations of cob houses such as 'Earthship', a style created by Michael Reynolds. The term refers to a type of low-impact building, made with recycled and totally sustainable materials. A curious feature of these houses is that they include glass bottles in the walls. This really is an example of recycling and circular economy taken to the extreme.

Photographs | Wikimedia commons, Flickr/Kobapan, Sota Construction Services, Kevin McCabe

Related content

Recommended profiles for you

Remember to activate your profile to network!
Activate profile
Smart Cities Business Manager
Jacqueline .
Universidad Ana G Mendez
Nyetiobong William William
Nyetiobong William William
Global Environmental Circle
Managing Director
Chirag Mistry
Chirag Mistry
Furniture Arts
Business Development
Jim Haskins
Cisco Systems
Business Transformation Strategy & Planning
Cristina Wyatt
Cristina Wyatt
UC Berkeley College of Environmental Design
Currently pursuing Sustainable Environmental Design, and open to opportunities!
Gonzalo Ponce de León
International Business Development
Mariana Pallarés
Mariana Pallarés
Local Pathways Fellow
Alejandro Hidalgo
TriDimensión consultora SpA
Urban architect with an interest in urban planning and sustainable cities
Anas Abdelhafez
Anas Abdelhafez
Smart Cities and Communities Director
christian carreira
Business Development Executive\\nCities, Public Lighting & Safety Solutions
Andres Fernández
Andres Fernández
Kris Arel
Tito Aribowo
GBC Indonesia
Program Development Manager
priyamvada Gaur
Erik Van den Broeck
Erik Van den Broeck
BDO Advisory
Partner BDO Real Estate & Construction
Vic More
Oluwaseun Adeyemi
Debt Management Office (DMO) Nigeria
Operations Officer
Abhishek Dand
Adani ports
Sr. Engineer
Toni Sanchez Poyato
Toni Sanchez Poyato
Schneider Electric
Business Development Smart Buildings

Thank you for registering to Tomorrow.City. You can now start exploring all the content for free!
Only accessible for registered users
This content is available only for registered users
TO: $$toName$$
SUBJECT: Message from $$fromName$$