Sustainable building material: Why don't we use more mud bricks?

Adobe, aka Mud Brick has been used for centuries and are often considered as sustainable building material.  This material primarily uses in the Middle East, East Asia, North Africa and South America. Mud brick are formed locally by using site raw material, water, sunlight and mostly human labour.

Mud brick being formed.

Photographer: Paul Downton,

From: http://www.yourhome.gov.au/materials/mud-brick

The bricks are often use to construct small scale building. The amounts of usable bricks are dependence on the available site material. Therefore you would rarely see a high-rise with mud brick as the primary material.

Here are some key benefits of using Mud Brick:

• Environmentally friendly, due to usage of site material.
• Energy efficient - Little or no process of the raw materials and energy inputs would be directly or indirectly from the sun.
• Economical building material - made by using existing site earth with water. Straw fibres and other fibres can be added for tension and reduce the chances of cracking. Brick moulds can be made from timber or metal.
• Once it reaches it's lifetime of use, the bricks break down into the earth they came from
• It is say to be the lowest impact of all construction materials
• Able to provide medium to high thermal mass
• Fire and vermin resistance

After knowing all these benefits of mud bricks, I was curious to see why we are not seeing it more often in the building and construction industry. One of the major barrier is, the making of mud brick is labour intensive. Typically, a house requires 10,000 to built but a working couple will at most get 200 bricks made per week. This is due to the long process of allowing the mud bricks to be dried evenly, required to be covered, avoid direct sunlight and overly quick drying. Considering the amount of labour that goes into making the brick, I'm very curious to know the cost of making a mud brick in comparison to a standard clay brick. 

Although there are a number of mud brick manufacturer who produces commercial mud bricks, but personally, that will defeats the purpose of maximising site materials. Not only it is labour intensive in making, it is said that it also requires more attention to maintenance due to its sensitivity to moisture. 

Base on my experience in working in the landscape and civil industry, I believe the use of mud brick in the application of a small retaining seating wall is quite reasonable. Many designers uses sandstone logs to create these seating walls. Instead of consuming the energy required to quarry sandstone, cut it to shape and transporting it kilometers away from the quarry, we should consider using mud bricks instead (given that the site site has the right mix). 

Interesting precedents:

http://www.worldcrunch.com/tech-science/mudbrick-modern-architecture-dusts-off-old-green-ways/c4s20771/

http://inhabitat.com/bioclimatic-preschool-is-built-with-rammed-earth-walls-and-mud-bricks-to-keep-cool-in-the-moroccan-heat/