After saving money to buy land, for most people, the next huddle is finding the money to buy building material, starting with bricks and cement. Interestingly, there is a cheaper and more environmental friendly way to build a house without compromising on its standard.
Interlocking blocks have been around the construction market for a while. They are made from either soil only or cement only.
However, nowadays, there is an emerging trend where interlocking stabilised soil blocks (ISSB) are used because they are much cheaper. They are made of soil with a small mixtureof cement.
Stephen Jjuuko Kwagala, a graduate architect and contractor, says the bricks are 10 per cent cement while the rest is murram soil. “Just as our grandparents used grass to stabilise soil before it dried on the walls of their huts, we use cement to stabilise the soil in the ISSBs. Only selected murram which does not contain organic matter is used. Basically, we just take the top soil off and use what is beneath.”
The most common type of bricks on the market are clay and fired bricks that contain a mixture of soil, sand and cement. They are also smaller in size when compared to ISSBs.
Less mortar used in ISSBs
With ordinary clay bricks or fired bricks, a builder has to use about two inches of mortar as they stack the bricks together to form a wall. With interlocking bricks, however, a builder will use only half an inch of mortar. A more sophisticated constructor may choose to use the dry stacking method, where the bricks are stacked one on top of the other without mortar.
Kwagala says with ISSBs mortar is only used as you stack the bricks horizontally. “We do not use mortar in the vertical spaces between the bricks because interlocking bricks come out of the machine when they are straight and have the same thickness. This means a builder can save about one third of the amount of plaster needed. This is not the case with fired soil bricks where each brick is unique and different from the rest.”
Small interlocking bricks cost Shs450 per brick, while the large ones – which are 22 centimetres wide – cost Shs650 per block.
A first time builder may wonder if the building will last long with so little mortar between the bricks, however, Kwagala allays their fears. “The interlocks are a more sure thing than mortar. Once they hold together, then on a wall, the mortar is the weakest part. People should instead worry about the quality of cement being used in mortar. At the end of the day.
The obvious advantage of using interlocking bricks is that their production process is environmental friendly.
“Making clay bricks is damaging to the environment because the workers destroy wetlands in their quest to find clay,” Kwagala says, adding, “In the same way, those who make fired bricks use a vast amount of firewood in the kilns they use.”
ISSBs are cheaper because they can actually be made on the building site.
A mixture of eight wheelbarrows of soil and one bag of cement can produce 150 bricks. After mixing the soil and the cement, a little water is added and lumps of the mixture is put in the machine, which will either produce hollow or solid blocks depending on the client’s preference.
“The production time is shorter because we can make the bricks in the morning and use them for building in the afternoon of the same day,” the graduate architect advises, continuing, “A client does not feel cheated because they can supervise production and physically count the bricks. Also, they are saved the cost of transporting the bricks to the building site.”
Applying finishing to a building or just a wall can be very expensive. Stephen Jjuuko Kwagala, a graduate architect says this brick has a more natural look. The mixture is applied to the wall like any other plaster and while it is still damp, a trowel is used to put the lines where the bricks have interlocked.”