Building blocks for the future
What are interlocking blocks?
These are like two adjoining pieces of a jigsaw puzzle. Each block has a projection at one end and a depression on the other. The projection of one block fits into the depression of the next so that they always align perfectly. The blocks have vertical holes in them which have a double purpose.
Firstly, the holes reduce the amount of material required to make the block without compromising on its strength. Secondly, steel rods can be inserted or mortar poured into them to increase the building’s strength and stability.
How does this technology help in reducing the cost of buildings?
There is no need of using sand since the blocks interlock leaving no space. Also the soil used is on site and this reduces the cost of transportation by about 30 per cent.
With this technology, the period of constructing a house is reduced by half and this makes the cost more affordable. The duration of constructing a house ranges from 2 weeks to one month after production and curing of the blocks depending with the size of a house.
What soil is required to make the blocks and how long does it take before the blocks are ready?
Red soil is the best. Black cotton soil is not viable as it contains highly reactive clay and the blocks will crack when they dry. Generally, you can use soil with 15-35 per cent clay and silt content. The process of making them takes 21 days and this includes the curing process.
Does the adoption of ISSB Technology adversely affect the environment?
Small scale application of ISSB technology poses minimal negative effects to the environment. In most instances, the resultant burrows can be put into other uses such as development of septic tanks, toilets, foundation of buildings, compost manure sites, tree growing, farm gardens, water pans, fish ponds, rubbish pits among others.
What are some of the challenges facing this technology?
Dishonesty by some clients who deviate from the recommended ratios that later compromise the quality of the building has been the main challenge. Though the county governments have bought the block making machines, there is lack of sensitisation and this hinders people from embracing the technology.
Which is the most cost-effective housing delivery mode using ISSBs?
For single houses and community projects, a labour based contract using trained artisans, (fundis) could suffice. But for large projects, use of professionals is necessary.
It is critical for technology use seekers to liaise with County Directors of Housing to get contacts of trained fundis in various counties. A list of currently identified ISSBs professionals is provided on the ministry’s website link.
Why do you think that interlocking blocks is the way to go?
Although building techniques and materials have evolved over thousands of years, construction is still a long, complex, and expensive process. And it is, by and large, not environmentally friendly.
The energy required for construction, the materials used and the pollution that is to be found in the construction area are among the many things that negatively impact the environment. Interlocking blocks may not solve all construction problems, but they do resolve many issues associated with traditional materials.