Local block, dry stacked
After hiring countless concrete consultants and builders, we’ve eventually formalized and launched an elegant solution to the high cost of building homes for the poor. We’re so excited about this initiative that the foundation bought four brand-new concrete block-making plants. Each plant can produce 12,000 standard 8″x16″ blocks per day (running three shifts of at least three workers each). One plant is now operational in the Bahamas. We’re looking to donate the others and partner in their implementation.
LOCAL MATERIALS: almost 90% of the homes’ structure comes from local sand and aggregate (the small portland cement component is often imported). 12,000 blocks per day is enough capacity to build dozens of family homes per week. The block plant requires a 20kw generator and produces good quality blocks for about 7o% less cost – while creating local jobs.
DRY STACKING: If you’ve ever done any construction yourself, you’ll know that laying blocks or bricks is quite tricky. You have to get the mortar just right. Masonry is a skilled trade rarely found in abundance in the developing world. But engineering research published by the USDA long ago proves that you don’t need to mortar between the blocks. In fact, tensile strength is 6x better if the blocks are merely stacked dry (which is really easy and fast). The same rebar is inside the walls for strength, just like with traditional construction. But a special strong kind of stucco is applied to the inside and outside of the wall to achieve ‘surface bonding’, which happens to also provide an attractive finish.
The combination of cheap local materials and easier installation is a cornerstone of our construction initiatives and a big win for our TownStarter program.