Auger Cast Piles vs Helical Piles

Piles are a common foundation choice for both residential and commercial construction, in many beachfront areas like Palm Beach County piles are an engineering requirement due to the sandy soil. There are two main types of piles used in and around Palm Beach County: auger cast piles and helical piles. Both have their pros and cons, so how do you know which is the best pile type for your project? In this blog post, we’ll compare auger cast piles with helical piles to help you make the right decision. Stay tuned!

What are Auger Cast & Helical Piles?

Both of these are screw type piles as opposed to driven piles. That means that a large machine is required to screw into the earth. (Driven piles are hammered into the ground).
Cast Piles” include pouring concrete into the hole, thus “Auger Cast Piles” first require an Auger bit to drill the hole into the ground, and then fill the hole with poured concrete, and optionally steel reinforcement. This process has advanced to the point that the concrete is poured into the hole while the auger is still in the hole.
Helical Piles” are large steel poles with screw blades attached. These poles are screwed into the ground and the whole thing is left in the ground.

How do Cast Piles and Helical Piles work?

Cast piles are easy to understand, a deep cylindrical hole is filled with concrete and reinforcing steel, this then becomes a foundation pile. The stability is provided by the large surface area (friction based) and compression on the base (end bearing). Compression is very high in cast piles and can sustain large weights, however tension is not as high as Helical piles.

Helical Piles work by screwing into the earth and provide load bearing due to soil compression and end bearing. Helical piles are generally better in softer sandy soils than Cast piles. They are quick to install and provide almost no spoil.

Advantages and disadvantages of Auger Cast Piles

  • Speed (fast)
  • Have to wait for cast piles to cure
  • Must wait for grout/concrete delivery (time sensitive)

Advantages of Helical Piers

  • Speed (faster)
  • Can be used immediately after installation
  • Load capacity can be monitored during install
  • Good choice where groundwater is an issue

Screw Pile Cost considerations

Most building materials have increased dramatically recently, and timely supply is an issue. With that comes cost increases, but overall Helical Piles are less expensive and faster to complete the entire project (when supply is not an issue). Generally unless you are the engineer you will not have the choice.

Which type of pile is right for your project (Engineer’s Choice)

Generally the engineer on your project will decide what type of pile will be used. Factors that influence the decision are predominantly based on soil conditions. However other factors that effect the decision are…

  • Noise & vibration limitations in the area
  • Access to the site
  • Uplift consideration
  • Overall load
  • Environmental

Alternative names for auger cast piles.

So, what type of pile is right for you? There are a number of factors that will help guide your decision, in many instances engineers will give you the desired pile based on county or city requirements. Engineers will take the following in to consideration… How long will the pile need to be in place? What types of soil do you have on site and how deep would they need to go? Is it important for frost protection or drainage needs? Will there be any heavy loads placed on top over time (think pool)? All these questions can help determine which type of foundation might work best for your project. Give us a call today at 561-660-8277 if we could answer any other questions about this topic!