(ISSB) Interlocking Stabilized Soil Blocks

NyumbaBora aims at working in conjunction with the Ministry of Transport, Infrastructure, Housing and Urban Development to promote the use of ISSB (Interlocking Stabilized Soil Blocks) across all counties due to its high appropriateness, local availability, small scale application and potential to address poverty and housing affordability challenges facing majority of Kenyans.Research conducted by UN-Habitat 2014, states that roughly 56% of the Kenyan population dwells in slums.

The Eco-friendly Building Material

Eco-friendly materials are characterized by low embodied energy and low related emissions; they are durable and convenient for recycling and reuse. Traditional building materials are mostly made from naturally available materials such as clay, stone, sand and biomass.

The selection of appropriate materials should be driven by local/ regional and environmental considerations. Alternative technologies refer to materials, methods and/or practices which help protect the natural environment, take inspiration from the cultural values and practices in the area, make use of local resources, and contribute to local economic development. Interlocking Stabilized Soil Blocks (ISSB) is made of a compacted mixture of soil and a stabilizing agent such as lime or cement. They are formed in moulds that form grooves within the blocks such that they interlock horizontally and or vertically. This technical note focuses on the use of Interlocking Stabilized Soil Blocks as an alternative building material.

Advantages of ISSB


  • ISSB technology allows the production of uniform blocks with greater strength than fired blocks, concrete blocks etc. These blocks have a high density which gives it more load bearing capacity and improved water resistance.
  • Due to the high density and thermal properties of soil, these blocks provide better thermal insulation by the ability to absorb heat during daytime – keeping buildings cool inside, and to release that heat inside buildings at night, keeping them warm.


  • ISSB’s are cured in the sun hence there is no need for fuel such as wood thus saving the environment from degradation.


  • Due to the interlocking nature of ISSBs, far less mortar is required thus saving on construction costs.
  • Since the blocks can be made on site, costs associated with their transportation are eliminated.
  • Due to their appearance, plastering of the walls can be avoided further reducing construction costs.
  • Using the blocks results to fast construction since they are largely stacked and have no curing time.

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