Which is Better: ECP Steel Push Piers or Helical Piles?

By D.J. Clayton, PE

There are many options when selecting foundation underpinning. In addition to steel resistance push piers and helical piles, also known as helical piers or screw piles, other repair methods include drilled caissons that are concrete filled (with or without steel reinforcement), mudjacking, pressing small precast concrete cylinders, high-pressure deep grout injection, micro-piles and supplemental concrete spread footings.

This is not a comprehensive list of underpinning and other repair methods. It is only presented to acquaint you with some common foundation repair methods.

But Which is the Best?

Manufacturing and Installation Quality Matter

The way to get the best foundation underpinning repair is to use a product manufactured to high quality standards and installed by trained technicians.

Of all the different underpinning support methods mentioned, the premium products that stand out are ECP Steel Push Pier and Helical Pile.

The important benefit of selecting and installing an underpinning system manufactured by ECP is that every ECP Steel Pier™ is field load tested after it is installed. ECP helical piers, also known as torque anchors, have shaft torsion data recorded continuously during installation.

These data are used to verify that the required load capacity was achieved. This ensures that each underpinning installation provides stable, long-term support.  

Not only are ECP push piers and helical piers both designed to support the structure’s weight, but the design also adds a “Factor of Safety.”

A Factor of Safety means these products can support a significantly higher load than is needed for long-term everyday foundation support.

Immediately after installation, these products have data recorded that verifies the design load capacity. ECP foundation support products are not put into service until each pier has data proving sufficient capacity to support the load requirement plus a Factor of Safety.  

“Factor of Safety” is extremely important because it is “insurance” added to each pier design and provides peace of mind. With a Factor of Safety in place, future settlement is essentially non-existent. Most other foundation support methods cannot offer this kind of field data that verifies the design load capacity.

Helical Piles vs. Push Piers: Strengths and Weaknesses 

So which is better, push piers or helical piers? The simple answer is, “It depends.”

It is impossible to say that one method is better than the other. This is why it is a good idea to consult a registered professional engineer before investing a small fortune in foundation repair work. You need to understand the pluses and minuses of the different products and installation methods related to YOUR unique situation. Once you have this knowledge, it is much easier for you to make an informed choice.

Remember that many foundation repair salespersons will attempt to sell whatever repair method they represent. The salesperson does not care whether they offer the best repair method for your situation; they are only interested in a quick sale and commission.

By comparison, a well-established foundation repair company that offers both resistance or push piers and helical piles is a good place to start searching for the best way to lift and restore your foundation. A company with a long list of successfully completed projects — a company that offers more than one type of foundation support product — can suggest to you the best and most economical solution for your situation.

Foundation underpinning products in detail

ECP Steel Push Piers

ECP steel push piers are a premium foundation support product installed by carefully pushing high-strength steel pier pipe through the failing soil.

The installation of the pier pipe continues until the bottom end of the pipe encounters solid rock or load-bearing stratum. Once end-bearing resistance is encountered, the pier is field-tested to verify load capacity and stability.

Year after year, ECP steel piers have proven to successfully provide reliable long-term end-bearing support under structures.

Benefits of ECP Push Piers

1. Small, hand-dug access holes are needed to install the ECP push piers. Once the installation is complete, the excavated soil is replaced, and it is usually very difficult to see where the work was done.
2. The steel pier installation equipment is portable. No heavy equipment is required. Everything needed for installation, testing, and restoration can be carried in a wheelbarrow.
3. ECP steel piers are strong. The strongest ECP push pier has an ultimate capacity of more than 57 tons! How much weight is 57 tons? If you stack eleven 2018 Ford F-150 pickup trucks on top of each other, the total weight of all trucks would be just under 55 tons! ECP push piers can also be installed from INSIDE the basement in any weather.  
4. Hydraulic equipment is used for installation, testing, and restoration, meaning the work is vibration-free and relatively quiet.
5. Very little overhead clearance is needed to install ECP push piers, which is a benefit when installing piers in confined spaces like under elevated decks, under obstructions or balconies, and in crawl spaces.
6. The very first piece of pier pipe that goes into the ground has a collar at the bottom, which is visible in the illustration. This collar reduces soil friction while installing subsequent sections of the pier pipe. Because of this special collar, the pier pipe can be pushed as deep as necessary to reach the depth of rock or verified suitable load bearing.
7. Every ECP push pier installed is field load tested before being approved. Once rock or suitable end bearing is encountered, each pier is subjected to a field test load much greater than the force required to recover lost elevation and provide long-term support.

Helical Piles

ECP helical piers directly obtain support from dense and stable soil below the ground surface. The helical screw pile is advanced into the soil by rotating the pile shaft. The pile advances downward by three inches per shaft rotation as the shaft rotates. One or more helical plates are welded to the bottom end of the shaft. The shape of the helical plates is much like a single thread on a wood screw.

Finding a Load Bearing Stratum of Soil

The question is, “How does one know when the helical plates are embedded into a stratum of soil having suitable density for support?”  This is an excellent question. If an on-site soil test boring and analysis is available, a geotechnical boring log and report would clearly define the target soil and depth.

The problem is that residential projects are usually not candidates for soil testing. Soil boring and geotechnical analysis are usually cost-prohibitive and intrusive on a small residential lot. Soil boring equipment is mounted on a truck, and the truck must drive to the job site to perform test boring and soil penetration tests.

OK, if there is no geotechnical data, how does an installer know when the helical screw pile has encountered a layer of soil that has suitable strength to support the structure properly? The answer: The installer must monitor the torsion (twisting) of the pile shaft during installation to determine if the soil stratum is suitably dense.

Measuring Torsion Key

Helical screw piles have been in use since the late 1800s. Over the years, scientific testing has allowed engineers to develop an empirical formula for converting the amount of torsion applied to the shaft (The amount of twisting of the helical pile shaft.) to arrive at a highly accurate estimate of the installed ultimate pile capacity.

Well-qualified and experienced installers usually know how deep they need to go to reach a suitable soil stratum in a given neighborhood. This layer of soil has sufficient bearing capacity for structural support. These companies use a regional map to plot the depth-to-load-bearing for each project that they complete. Over the years, depth-to-load-bearing patterns can be seen on these maps. From this data, the installer or engineer can estimate the target depth at a given location quite accurately.

Very heavy structures with full basements and fill soil against the wall may not be the best choice for helical screw piles for inside the basement installations. This is due to the limited overhead clearance available in most basements. However, if the soil outside of the basement wall is removed, then screw piles are excellent products for foundation support and restoration.

Benefits of ECP Helical Piers

1. Small, hand-dug access holes are all that are needed to install helical piers. The excavated soil is replaced once the installation is complete, leaving everything clean and neat.
2. Helical piers are the best choice when rock is situated very deep. In such cases, the helical plates encounter load bearing at dense soil at a more shallow depth than the depth required for an end-bearing steel pier to encounter rock. In this case, ECP torque anchors are a lower-cost option.
3. The installation equipment for helical piers is hydraulic and portable. The product works very well in slab applications, new construction, and repairs with walk-out basements.
4. Hydraulic installation equipment means that pier installation is vibration-free and relatively quiet.  
5. Every ECP helical pier has the shaft torsion (shaft twist) monitored and recorded continuously during installation. Based on the estimated structural weight that the pile must support, the technicians know the minimum shaft torsion required to achieve the foundation support requirement for the project. Of course, an additional “Factor of safety” to ensure long-term trouble-free support is always included when determining the minimum shaft torsion requirement.
6. It is not a problem if an ECP helical pier does not develop the anticipated capacity when fully installed on site. Occasionally, this can occur, even when geotechnical soil data is available. The solution is simple. The installer will “unscrew” the helical pile, much like removing a wood screw, then the installer can add a helical plate to the existing configuration or change to a different helical pier that has a larger helical plate area to increase the load capacity. There is no money lost or any product wasted.

What Does ‘It Depend’ On?

The structural weight needs to be estimated, architectural details examined, and the quality of construction assessed. In addition, the soil composition and soil strength must also be considered before selecting the best product for a specific project. The most economical foundation repair product can be determined by examining the structure and evaluating the soil at the site.

‘It Depends’ on the Structure:

The architectural constraints of your structure can determine which product is superior for the underpinning repair. It also helps you to verify which product is the most economical for your application. Before one can arrive at a decision, some questions must be answered:

“What is the weight of the structure?”

“Are there any architectural details that have concentrated heavy loads?”

“What is the quality and strength of the concrete foundation?

“Will the installation be made from inside or outside of a basement”,  

“How far apart can the underpinning be spaced?” (This can only be determined once the structural weight and the strength of the reinforced concrete foundation beam are considered.),

“What is the amount of overhead clearance available”, etc.  

‘It Depends’ on the Soil

The profile of the underlying soil strata and the soil strength relating to each stratum must be considered before the best foundation repair system can be recommended. Important questions also must be answered, such as “What caused the foundation to settle?” Soil questions that must be addressed are:

“Does the soil profile consist of nothing other than layers and layers of soft clay?”

“Is there rock below the soft clay?

“At what depth does bedrock or other stratum exist suitable for end-bearing structural support?”  

“Does the dense layer just seem to be ‘rock’? Is it only a thin layer of ‘hard pan’ that has insufficient support strength for the structural load?”

“Is suitable load bearing rock located at more than 50 feet deep below grade?”

“Has poor site drainage, underground water or plumbing leaks led to water intrusion?”

“Are there weak organic soils at the site?”

“Is the structure situated on unconsolidated fill? Are there huge rocks or debris in the fill?

“Is the soil corrosive?” Etc.

Hopefully you can begin to understand that research and exploration is required before it is possible to suggest a foundation support product that is the best and the most economical for your repair project.  

Focus on Quality of Materials, Craftsmanship

ECP manufactures ECP Steel Piers™ and the ECP Torque Anchor™ brand of helical piles. These products are manufactured in the USA from certified-quality steel under continuous quality control. ECP has independent certified installers who are trained in foundation underpinning repair, anchor installation, waterproofing, and external drainage systems.  

It is very important to choose a qualified and certified installer. Better yet, consider investing in the knowledge and opinions of a licensed engineer. If you have a foundation settlement problem, cheap and fast is NOT the way to go. Foundation underpinning should only be done by a qualified foundation contractor. Eventually, you will have to do it right, so why not do it right the first time? Look into underpinning options from professionals near you.