The quality of a house's foundation is what determines if it will be strong enough to stand the test of time. A strong foundation can last 100 years or more. A weak one can crack and shift allowing water seepage, insects infestations, and complete failure during an earth quake or other natural disaster.
The first step to ensuring a strong foundation is using good materials. Concrete begins with crushed rock, sand and cement, usually primarily consisting of limestone. These components are processed using specialized vertical conveyors and mixing equipment. If the proportions are off, or poor quality materials are used the concrete can be weakened and prone to crack.
Before the concrete mixture is poured, the site has to be readied for it. Space must be excavated, and allowance made for proper thickness of the foundation. If there will be a basement, egress window wells, plumbing, and electric wiring must be accounted for. Framing windows and stairs is an intricate process itself. To reinforce the concrete and increase tensile strength, steel rebar is placed in the concrete molds. Building codes require that all these steps be taken and this work will be inspected before the concrete can be poured.
When the site is ready for the concrete, it is normally poured straight out of the back of a concrete truck. Construction workers make sure it is poured evenly and tamp it down to avoid bubbles. This process can take several days depending on the size of the foundation.
Concrete foundations for buildings have been in use since the Roman Empire. But new processes and more efficient conveyors for bulk material make today's concrete stronger than the Romans would have dreamed. And in the process this new concrete has allowed us to build ever taller buildings, bigger cities, and more secure homes of all sizes.