What’s the Difference Between Push Piers and Helical Piers?

What’s the Difference Between Push Piers and Helical Piers?

If your foundation experiences settlement, you may have contacted a contractor who told you that you must stabilize your foundation piers. There are two kinds of piers used in foundation repair—push and helical. But what’s the difference between push piers and helical piers? And why would a contractor only suggest helical piers?

The simplest answer is that push piers are nails and helical piers are screws. One is driven, one is screwed.  Basically, helical piers and push piers accomplish the same thing. They add additional support to a foundation structure that is experiencing settlement.  You can use both to transfer the load below the soil that causes your home to sink. Both can lift or stabilize your foundation, and both are relatively easy to install without needing large, cumbersome machinery.

The Differences 

The main difference between push piers and helical piers is the method used to install them.  Push piers, also known as push “resistance” piers, are hydraulically driven or “pushed” deep into the soil below your foundation. It uses the weight of your house as a resistance to push from. Contractors install push piers parallel to your home’s foundation. 

Helical piers, or piles, are hydraulically screwed into the soil using powerful drive motors attached to some type of support arm. Helical piers then attach to the side of your foundation below the soil line with a bracket. Push piers attach to the side of your foundation first with a similar bracket, then use the weight of your foundation to “push” the piers into the soil.  Helical piers usually are installed at an 8–10-degree angle directed underneath your foundation. Push piers are driven vertically.  Helical and push piers install in sections of between 3.5 feet -11 feet.  Helical piers have round plates, called helices, that attach to the lower part of the shaft and create the screw. You can use one or more helices depending on the load requirements to support or lift the structure.  Both pier styles use a heavy steel bracket that attaches to the side and bottom of your footing, below ground, that allows the pier to provide lift and/or additional load support. 

Which Pier Works Best?

Both push and helical piers will offer support and lift for a residential foundation. There are only two limitations for push piers: a structure that is too light or soil that is wet or loose deep below your foundation.  Push piers generally drive to bedrock and must push against enough weight from your house structure to achieve that depth. If the soil is very loose, the push pier tends to bend or bough under heavy loads.  Push piers work best at depths of 80 feet or fewer but have been installed to depths of more than 140 feet.

Helical piers are screwed into the soil using powerful torque drives. They’re best utilized where the structure load isn’t sufficient for push piers, and where loose or loamy soil conditions exist.

The limitations for helical piers are generally load and financial considerations.  Helical piers generally don’t handle the load limits that push piers offer, unless you use a much larger helical pile. That requires a larger machine, which might not fit next to your house, or, due to its size, it could cause considerable damage to your landscape. If the soil is rocky or too hard, helical piers are very difficult to install deep enough to move the load of your structure below the poor soil conditions that caused settlement in the first place. The goal of all piers is to transfer the load to a better soil so that settlement does not occur again.  High-density soil is not conducive to a helical pier installation. With lighter load capabilities, it may also require more helical piers than push piers. Again, soil conditions are key to determining both the pier type and the quantity.

Pier Coatings: Yeah or Nay?

Helical and push piers are manufactured from steel. Moisture makes steel rust and corrode.  There is moisture in the soil below your foundation, so it is likely that the steel piers would quickly corrode and fail. Right? Not so fast. There are a few factors that go into determining how and why a pier needs to be coated.  Moisture isn’t the only reason steel corrodes. High-alkaline soil (soil that has either a high degree of alkalinity or a high percentage of sodium). Excessive corrosion can and will cause the steel pier to eventually fail. Moisture alone without other corrosive conditions would take years to cause enough corrosion to fail a steel pier. Don’t worry, though: most residential piers are either powder coated or galvanized with a zinc coating that will extend the life of the metal for 50 or more years.  Even if the piers are bare steel, the lack of oxygen deep into the soil where the piers have been driven inhibits corrosion substantially. If coatings are important to you, dipped galvanized coatings will offer the longest life for the pier. If you need more protection, a sacrificial anode can be added to each pier that extends the life to more than 100 years. The bracket attached to your home’s foundation is another issue altogether.  It should always be protected from moisture and corrosion.

How Many Piers Are Needed?

This is the number one question people ask us whenever we inspect a residential foundation. “If the piers can handle ‘X’ amount of weight, why do I need so many piers? My house doesn’t weigh that much.” The answer isn’t quite so simple. 

Your home’s foundation and the soil beneath will determine the type and number of piers installed. Next to the soil, the weak link in the equation is your footing, the concrete section that supports the perimeter of your home. Your home’s construction materials, type, depth, and the width of the footing will determine a weight or load per liner foot. This is known as the “dead” load. Combined with the “live” load—the added weight of attached parts of the structure—this provides a total load that will determine the number of piers needed to support the foundation. Weaker or more shallow footings require piers to be placed closer together so that the footing doesn’t fracture or break. Deeper or heavier foundations and total loads also require either larger piers or closer spacing. This is true for both push and helical piers.

Why Is My Contactor Pushing One Over the Other?

Without a detailed soil analysis, the only reason someone would use helical piers over push piers is to manage the extreme weight of the structure. As mentioned before, a light structure generally requires helical piers to lift and/or support the structure. Any other reason and the contractor either does not have the experience or the equipment to install alternative methods of foundation support. A qualified foundation repair contractor would not rule out anything until a specific repair method is determined. They may even eliminate the need for piers altogether. Pushing or screwing steel in the ground may not the best solution for your foundation settlement issue.

Want To Know More?

Foundation Tech, Inc. is a foundation repair specialist located in the Los Angeles basin. They provide push and helical piers foundation repair services throughout Southern California for both residential and commercial clientele. Do you have a problem? Interested in learning more?  Contact them.

What’s the Difference Between Push Piers and Helical Piers?
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