Nowadays construction companies tend to prefer poured concrete foundations than foundations made of concrete blocks. Concrete poured has become more popular for a number of reasons. Wall forms that are quick to set up and taken down, concrete trucks that can travel almost everywhere, and modern pumps and admixtures which make "impossible pours' almost common.

Despite all the advantages mentioned in the previous paragraphs, concrete block has its place as an acceptable foundation material. When the foundation is small for a home addition, for instance, a builder can save money by laying up blocks instead of subcontracting the work out to a foundation contractor. Additionally foundations for crawl spaces can be quickly and economically constructed using blocks of concrete. If you are a DIYer with masonry skills, this material provides the chance to build the foundation block by block each step.

Before we dive into the "heavy" subject, it's worth clearing up some terminology. In the construction industry concrete blocks are called "CMUs," short for concrete masonry units. Beyond the typical 16 x 8 x 8 in. concrete block that is sold by the majority of stores for home use, the variety of CMU dimensions, shapes and the finishes on their surfaces is simply amazing. A majority of the CMUs are specifically designed for commercial construction.

Concrete blocks are created using the same components that are used to make concrete walls: gravel (called aggregate) and sand Portland cement and water. Lightweight blocks are sometimes called cinder blocks because they contain fly ash (cinders) which is a byproduct of industrial combustion is utilized as a partial substitute for heavier ingredients like sand and aggregate. The hollow cores found in many CMUs help to make the block cheaper and easier to handle. They can cinder block fence also be filled with cement, sand or foam insulation to increase the durability, thermal mass or insulation value.

Contrary to popular belief the concrete block foundation isn't inherently inferior to a concrete foundation, providing that it's properly constructed. Both kinds of masonry require steel reinforcement and must be placed on a sturdy, stable footing. A good drainage system and damp proofing details are crucial. When expansive soils or other external forces harm a concrete block foundation cracks usually appear along the mortar joints that create the separation between individual blocks.