Different Types of Foundations and Footings in Building Construction Projects

09 August 2017

What’s at stake when the foundations of a building are spread out on the draughting table? Well, this substructural framework, composed of a foundations and footings system, is tasked with a heavy burden, both figuratively and literally. Designed to absolutely support the structure that’s rising above that ground parcel, there are different types of foundations and footings in use today. Let’s explore these support systems.

Building Strong Foundations

Like the threads on a patterned swathe of fabric, concrete and steel-reinforced tie bars lace the excavated ground. That ground has been surveyed, cleared and graded, and prepared for the foundations. First of all, after this pre-construction stage, the footings are constructed. This term refers to the core concrete and rebar segments that frame the substructure. They’re typically laid in an open trench, then the foundations spread across the entire area until the structure’s ground level is established as a level, hardened layer of load-bearing concrete.

Deconstructing Different Foundations Solutions

Soil types and structural engineering attributes dictate the different types of foundations and footings. Depending on that load and the building’s configuration, spread footings are a logical choice. Built wider than the walls they support, these extended concrete blocks spread the load when they shadow the outlines of the above structure. On the other hand, spot footings work best when the structure is raised on an array of pillars. Meanwhile, above the footings, the building’s foundations also vary. Floating foundations don’t even use footings. Instead, a large volume of soil is removed, then the concrete foundations are anchored to the underlying sub surface ground. Desirable in regions where ground liquefaction and seismic events occur, this foundation type is also known as a slab foundation.

Ground-Based Structural Suitability

Strip foundations and trench footings are sidestepped when raft or mat configurations are employed. Used often in large sites where floor space considerations are hampered by poor soil conditions, the layered concrete extends across the site, alternates with waterproof layers and tiers of hard rocky deposits so that structural integrity is assured. From here, the diversity of the engineering science divides further. Concrete piles and screwed metal rods act as concrete-less anchors. Finally, the survey accounts for the lay of the land, so arched and stepped foundations counteract the horizontal and vertical loads incurred by a building’s bulk.

Trenches fill with footings concrete. The long, reinforced slabs of cured concrete then follow the outlines of the foundations, or they form pads and steps, the underlying outlines that support different foundation types. As for those ground-level structural support systems, there are raft and floating variants, plus a number of load support classes that vary in profile to match the lay of the land. Finally, alongside the pad footings and poured concrete slab foundations, keep an eye open for helical screws, for a rod-based configuration that’s currently making inroads as a cure-free deep foundations system.

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