Interlocking Stabilized soil blocks are walling blocks made from compressed soil. They are just as hard and as water-proof as stone. Stone is made when soil is compressed by forces of nature while the Interlocking Stabilized Soil blocks are made when the soil is artificially compressed.
Interlocking Stabilized soil blocks are artificially compressed using either a manual or diesel-operated pressing machine to a pressure of between 20 to 40 kg/cm2.


Quarry stone has a compressive strength of between 2 to 5 N/mm2 depending on the type of stone which varies from region to region.
Interlocking Stabilized soil blocks have a compressive strength of 2.5N/mm2.
This shows that they compare well to quarry stone in terms of strength.
Reinforced concrete has a much higher compressive strength that exceeds 15 to 20N/mm2 depending on the mix ratio of cement; sand; ballast.



Assuming an average price of KES 750 for a 50kg bag of cement, and KES 350 to 400 for unskilled labour per day, the cost of producing 1 meter squared is as below:

CEMENT-KES 7 per brick
LABOUR to manufacture brick-KES 4 per brick
LABOUR to make wall-assuming 1 fundi and 1 assistant at a total of KES 1,100 per day with a minimum of 500 bricks per day.-KES 0.4 per brick.
TOTAL=KES 11.4 per brick.

1 M2 of walling will have an average of 33 bricks.

The total amount for 1 m2 of Stabilized soil walling will be KES 378 per m2.
The above estimate assumes that the soil is freely available at the site.

If the soil is bought, the cost will vary as below:

Assuming soil is bought and transported to the site at a cost of KES 500 per ton, this translates to 225 bricks per ton costing KES 0.3 per brick.
There will be an additional cost of KES 0.3 X 33 bricks per m2=KES 10 per m2.
This will total KES 388 per m2.


In Nairobi and its environs, since there are large construction projects requiring deep foundation excavations, soil can be delivered to the site for free since the large building owners are required to dump the soil in far away located approved council dumping sites hence more convenient for them to deliver to a nearby site.


Stabilized soil blocks eliminate the need for joining cement mortar in between the blocks. It also eliminates the need for plaster. It’s however recommended to paint is externally using water-proof varnish to make it more water –resistant.
Specific sections can be painted using contrasting colors to create creative interior wall patterns.


Machine-cut stone delivered around Nairobi costs between KES 60 to KES 70 per block.
In 1 m2 of wall, there are 13 stones. This totals to KES 60 x 13=KES 780 per m2.
The stones require cement mortar for joining. Each m2 requires approximately 1m2 of cement mortar at a cost of KES 200 per m2.
This adds the amount to KES 980M2.

Masonry walling requires plaster on the interior surface and key finishing on the exterior surface. This costs a further KKES 200 per m2, adding the cost to KES 1,180 per m2.

After plastering, masonry walling will need paint since the dull grey color of cement cannot be left bare compared to the reddish stabilized soil block color.
Paint costs a further KES 200 per m2, totaling the amount of masonry walling to KES 1,380 per m2.


Masonry walling costs 256% more than Interlocking Stabilized soil block walling.

In an average bungalow, the total walling costs compared to the total cost of construction is 15% .

The 256% difference in walling between use of masonry stone versus use of interlocking stabilized soil block happens only in the 15% of the total construction cost hence not being strongly felt.

For example, in the www.a4architect.com Diamond House design, the phase 1 [49m2] costs KES 853,000 to construct using masonry stone.

If the masonry stone is replaced with interlocking stabilized soil block, this 49m2 house will cost KES 796,000, representing a savings of KES 57,000.


To achieve maximum results in terms of cost savings in construction, a holistic approach whereby all elements of construction are taken into consideration, from foundation to walling, roofing, windows, finishes, external works.
This holistic approach to design has been researched and compiled as the www.a4architect.com Diamond House methodology.

Architect Francis Gichuhi Kamau



  1. Hey
    My name is Wairimu from nyahururu and am in the process of starting to build my home. kindly give me an estimate of building a 3 bedroom house with bricks.

  2. Thank you for the great work you are doing. I have not only enjoyed reading your articles, but am also learning a lot.

    My question is, can these blocks be used in the foundation walling in place of quarry stones? And if so, would they need to be made differently?

    Thank you.

    1. hi Eddah, thanks. The blocks cant be used for foundations coz they dont do well where there is moisture/water.

  3. Hi,gud job here.seems lyk there isnt much savings as uv shown btn issb n stones for a 49sqm bungalow.lets say ur doing a 150sqm maisonette,is it possible to do the same computations n come up with an average savings figure.i just thot that the savings in a maisonette wud b higher since a bungalow takes more in terms of foundation & roofing costs.thanx

  4. Nice article. Can interlocking blocks be used to build low-rise buildings, for example a maisonette or a Ground PLUS TWO home or apartment?

    1. i would like to inquire if you assist in constructing houses for people we have a house in umoja and would like to be assisted to raise it into a flat

    1. yes, it is very possible mr Hinga. we have several one two three storey we have built using these interlocking blocks.

      please reach me through the following number for more info: 0725234802

  5. Will be glad if i get help from you peple, am planning to build a family home with 4 bedrooms. please advise

  6. Am dreaming of erecting some bedsitters in Embu using SSb for the outer walling and ESP for the partitioning.I have read the presentations by various firms dealing in ESP including NHC and learnt that one can put up entire structure using these panels and floor slabs,staircases,etc but my fellow villagers are not completely sold on this muhindi technology hence the subterfuge( am assuming they dont mind SSb).Is there any cost saving in having panels for internal walls and interlocking for external? My plans are all approved by kanju,pesa ndio imekwama somewhere. Thanks a lot for your website.

  7. Hi.
    Am Mary from Githurai,Kiambu.

    Am planning to begin SSBs making.Where does one get a machine of max. 2000pcs per day?
    Wherre are ur offices?


  8. Greeting,
    I am impressed by the bricks you have introduced that may make life cheaper.
    Kindly advise how much would it take to build a three roomed house using the makinga bricks.
    Is it possible for the bricks to be delivered to Sofia in matuu and at what cost?
    How much is the total estimated cost for the house to be completed?
    Kindly advise urgently.

  9. Hi how much can it cost a four bedroom house in kantafu using interlocking blocks thanks. I like your good job done

  10. Am interested in building a three bedroom house.Can you give the estimate cost of the structure,this including all finishes.Leave alone the roofing.

  11. Am Dominic Ogembo from Nairobi ,I have already acquired my interlocking brick making machine and currently making the brick upcountry (kisii)am only worried of the stability of my dream house ,Looking for an expert builder to help me achieved my dream.(misatiogembo@gmail.com is my email)

  12. Hey
    My name is Samuel from Kerugoya and am in the process of starting to build my home. kindly give me an estimate of building a 3 bedroom house with bricks.

  13. HI Arch. Frank, which soil would be best for the blocks? Red soil? Can one use fine quarry dust from stone/ballast quarries?

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