Building a cob kitchen, step by step.

This is some of the beautiful sensitive and unique work in cob and bamboo by Biju of Thannal Hand Sculpted Homes.... (click 'talking' to join the discussion in our natural building group)

  

 
     

Click 1 to 9 to see the steps
 
 

This cob kitchen was built by Biju of Thannal for a child care centre in Tamil Nadu, India.

With a large scale plan of the building on the ground the first day's work was marking out the foundation with sand [see picture 1]. Lime was used with fermented palm jaggery and gall nut to stabilise the mud (clay soil) making a cement free mortar for the foundation stones and stem wall [2].

   
           

The internal bamboo frame [3] for the roof is soaked in borax salts and protected at the foundation with tar. The cob for the walls was mix using oxen [4] to tread the clay sand and straw. The thick cob walls which will regulate the temperature in the building are gradually built up [5] around the bamboo frame reaching 9ft at their lowest and touching 14.5ft at the highest point with old car windscreens and windows built in to the walls [6]. As the walls rise their thickness reduces limiting the weight on the foundation and lower parts of the wall [7], a technique used in the adobe skyscrapers of Shibam. The roof [8] is a matrix of bamboo that provides shade from the strong Indian sun [9] and will carry small local clay tiles on the main roof.

You can see more pictures of the whole process on Thannal's Facebook page and website.

  
   
 
   
 
 
   
     
   


The walls of the building are plastered in earth using wheat paste to improve the workability and provide strength and adhesion.

Pictured (right) you can see sample patches of plaster to test various earth mixes on the exterior cob walls. Many samples were made to test the hardness and durability using lime, linseed oil, cactus juice with different mixes of soils and animal dung. See the video right.