Thousands of trees are cut down every year across East Africa to make traditional fired bricks for building in one the world’s fastest-growing populations.

With this loss of trees, there is catastrophic loss of biodiversity and huge carbon emissions.


A reliable, proven alternative to the fired brick is the Interlocking Stabilised Soil Block, a compressed earth block, mixed with a little cement and air-cured.

No trees are cut down to make the ISSB, there are dramatic savings in carbon and young people can be trained to use this affordable and sustainable technology.


An ISSB block is a block of inorganic subsoil, often called marram, which is mixed with a small amount of cement and sand and then manually compressed in a mould in a press.

The blocks are cured for 28 days and also have an interlocking feature that means much less mortar is needed between courses and buildings can go up more quickly.


The oldest ISSB structure was built by Dr Moses Musaazi over 30 years ago. Based on the blocks’ performance in the laboratory, well-built structures should last as long as traditional brick ones.

ISSBs undergo the same rigorous tests as other building materials. Tests show that ISSB’s often exceed minimum requirements of the Ugandan National Bureau of Standards (UNBS).

An advantage of ISSB is that each block is uniformly shaped. This means that without plaster, the exposed blocks look very smart. HYT chooses not to fully plaster its structures because savings are made, and the buildings look great.

ISSB buildings are similar in price to traditional brick structures. The cost savings using ISSB will derive from the walling; the more walling a structure has, the greater the potential savings.

HYT’s rainwater harvesting tanks have been independently tested for water quality. The results show that well-maintained tanks hold safe, clean water.

ISSB tanks are cheaper than steel tanks and are much more climate-friendly. ISSB tanks are similar priced to plastic tanks but HYT tanks are more durable and environmentally sustainable.

A team of trained masons can build a tank in 2 weeks.

Traditional burnt bricks require huge amounts of firewood during production. In Uganda, brick burning is the second largest driver of deforestation. ISSBs replace the need for burnt bricks and require no firewood, or costly transportation during their production. 

A typical HYT training programme runs between 4-6 months.

Uganda’s construction industry is booming, contributing to around 12% of GDP, and our graduates gain access to the many jobs on offer. Some of our ‘graduates’ continue working for HYT and become trainers themselves.

A team of 3 can produce 400 blocks each day, using one manual press machine.

HYT does not sell ISSB presses. Please visit Makiga Engineering for more information.