Shallow Foundations vs. Deep Foundations

Every building needs a foundation, but did you know that not every type of building has the same type of foundation?

There are two distinct foundation categories: shallow foundations and deep foundations. Shallow foundations are typically less than 6 feet below the first level of a building, while deep foundations can extend to 300 feet below the surface.

Continue reading to learn more about these two categories.

Types of shallow foundations

Shallow foundations, also known as footings, are usually reserved for smaller residential projects or wood structures when the soil near the surface has sufficient bearing capacity for the building. These are the different types of shallow foundations:

• Pad footings: Pad footings are the most common types of foundations. They’re used under individual columns, each with its own footing. They can be either square or rectangular shaped, depending on the type of column they’re supporting. The size of the footing is calculated by the column load and bearing capacity of the soil. Weaker soil often needs a wider pad to support the column above.
• Combined footings: Combined footings support two or more nearby columns in situations where individual pad footings would otherwise overlap. These footings are rectangular and only necessary when load points are close together.
• Strip footings: Also known as continuous footings, these are used under lines that are loaded throughout. They’re usually shaped like an L or an upside-down T and are common under bearing walls. Strip footings can also be used to support individual columns under these loaded lines.
• Mat foundations: A number of individual foundations can overlap when several different loads occur in an area. A mat foundation is required when that’s the case. These spread across an entire area to support structural loads from many columns and walls. Mat foundations can be up to 12 inches thick to support the structure above.

Types of deep foundations

Deep foundations are required when the soil is weak and the planned structure is four or more stories tall. These are the two types of deep foundations:

• Pile foundations: A pile foundation is made of concrete or steel and is designed to transfer heavy loads from the building to the hard rock below the ground. They’re used for structures where the shallow soil can’t resist settlement or uplift. Pile foundations can fall into several different categories, including sheet piles, load-bearing piles, end-bearing piles and friction piles.
• Drilled shafts: A drilled shaft is a type of deep foundation that provides structural support as well as earth retention. As the name suggests, drilled shafts are made by first drilling a hole in the ground; then we lower a massive steel support beam into the earth and fill the hole with concrete for added support.

Let us dig your next foundation

Whether you need shallow foundations or deep ones, trust our team at Estes Excavating Inc. We’re a licensed and insured company offering a wide variety of excavating and land-clearing services. Contact us today to see what we can do for you or to get a quote for your next project.

Categorised in: Foundations

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