What is a Deep Foundation?

You may know what foundation your home has, whether slab-on-grade or raised. Dalinghaus Construction has done repair projects on basements, even though they’re rare to find in Southern California and Arizona. Though what are the types used in the big apple, in the city of Angels, or in any other famous city that comes to mind? And what if those aren’t only used for large superstructures? Maybe that commercial office you work in has one, too.

If you want to learn about deep foundations or haven’t heard of them, this article is for you. 

Dalinghaus Construction has inspected over 10,000 homes in Southern California and Arizona. We’ve repaired thousands of foundations, with a fraction of them being considered “deep.” While our experience in dealing with deep foundations is limited, it doesn’t mean we aren’t willing to learn more about them and use the experience we do have for quality work, regardless of foundation type. 

What is a deep foundation?

This type of foundation reaches down deeper to carry a heavier load, going past the surface of the soil that is most affected by the elements. Deep foundations either carry loads on weaker and softer soil, contact stronger soil that is less compressible or are created for functionality. 

How far does it go? It goes as deep as is needed. It depends on the weight of the building. Piers necessary to put in the ground can go as deep as 50 feet. Sometimes they go as deep as 300 feet. Those piers are like Leonidas and his Spartans surrounded by the Persians– in this case, the soils before hitting bedrock. The depth of the piers depends on the materials of the building. And if the building is taller, it will hold a larger load of that material. 

This isn’t to say it’s only large buildings with deep foundations. A building the size of an average home may need a deep foundation depending on the equipment inside. If you run a machine shop, you have a whole lot of heavy equipment. What holds that equipment better? A deep foundation.

These types of foundations are more prevalent on the commercial side of things. Commercial buildings tend to be larger, which means more weight to hold. Superstructures such as skyscrapers will also require deep foundations. So those skyscrapers that make you feel like you’re an extra in Honey I Shrunk The Kids have unseen foundations larger than you. 

The different types of Deep foundations:

  • Basement Foundations

You may be familiar with these if you’ve watched an episode of Stranger Things to see Mike, Will, and the rest of the crew play Dungeons and Dragons. It’s a good game. Basements are substructures built under a house to provide storage or working space below ground level. 

  • Buoyancy Rafts / Hollow Box

These are often referred to as the floating foundation, even though it goes underground without floating. Having foundations float like Aladdin on his magic carpet would make our jobs so much easier. This type of foundation replaces weaker, softer soil. The foundation installed is equivalent to the weight of the structure built on top, counteracting the force exerted. With them counteracting each other and maintaining stability, this foundation is, for lack of a better image, “floating.”

  • Drilled Shaft 

Drilled shaft foundations are installed by excavating a deep hole in the ground to place a steel case lining. These linings are typically filled with concrete or some other load-bearing unit. These are high-capacity deep foundation systems.  

  • Caisson

Caissons are hollow substructures sunk into the desired depth and then filled with concrete.

  • Cylinders 

This is a type of caisson made of concrete used for water environments. Cylinders are used for structures such as bridges, docks, and piers. 

  • Pile Foundation

This deep foundation uses columns or long cylinders made of concrete or steel. These use skin friction or end bearing to transfer the desired load onto the structure. The cylinders put in are filled with concrete. 

Will you see deep foundations in residential areas?

If it’s a basement foundation, you won’t likely find them in Southern California compared to other states. But if you’re thinking something to the extent of what a skyscraper has to use, I mean it could happen. It’s like when you find that one french fry in your onion rings; it’s very rare. Or like getting struck by lightning seven times–it has happened! Ask Roy Sullivan. You’ll more than likely start seeing deep foundations on big mansions or big hillside mansions. Your standard suburban home more than likely won’t have a deep foundation. 

Generally, if a structure doesn’t need that type of foundation, it likely won’t have it. Why? Because of cost. It always comes back to cost. The fewer materials needed, the less cost of installation and repairs.

If you or anyone you know has a house with a deep foundation that isn’t your standard basement, feel free to let us at Dalinghaus Construction know. We also want to see that unicorn among the horses. 

Why learn about deep foundations?

I mean why not learn about them? Dalinghaus Construction works on mainly residential homes. We’ve worked on commercial buildings with deeper foundations, though we get these jobs as much as we’re able to find four-leaf clovers. 

Regardless if the foundation is shallow or deep, they both settle the same. And we never settle with bad foundations. 

Are you concerned about your foundation? Are you not sure what kind you have? We’ll check out all types. We’re here for you with a free foundation evaluation or give Dalinghaus Construction a call at (877) 360-9227 with any questions you may have.


Justin Sexton

Justin joins the Dalinghaus Construction family with a significant background in logistics and project management. He joined the team in early 2017 as a foundation inspector, but quickly transitioned towards a marketing role. He now manages the marketing department and creates everything that you see from us digitally.

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