Screw Piling Costs Compared to Bored Pier Costs

Comparing the Costs of Bored Piers and Screw Piling: Which Foundation Solution is Right for Your Project?

Choosing the right foundation system is crucial for structural integrity, cost efficiency, and overall success when planning a construction project. Two standard deep foundation solutions are bored piers and screw piling. Both have advantages, but their costs vary significantly depending on project requirements, soil conditions, and installation complexity.

Bored Piers: Strength and Stability at a Cost

What Are Bored Piers?

Bored piers (or drilled shafts) are cylindrical concrete foundations installed by drilling holes into the ground, reinforcing them with steel, and filling them with concrete. They are commonly used in projects requiring high load-bearing capacity and stability.

Cost Factors

• Excavation & Drilling – Requires heavy machinery, which can be expensive.
• Material Costs – Concrete and steel reinforcements add to the overall cost.
• Labour Intensity – Installation is labour-intensive, requiring skilled workers.
• Site Preparation & Spoil Removal – Excavated soil and debris must be removed, adding to disposal costs.
• Weather Dependency – Wet conditions can delay installation, increasing labour and equipment costs.

Estimated Cost Range

Typically, it ranges between $350 - $800 per linear meter, depending on soil conditions and project complexity.

Screw Piling: Cost-Effective and Efficient

What Is Screw Piling?

Screw piles are steel shafts with helical plates that are twisted into the ground like screws. They provide strong load-bearing support without the need for extensive excavation.

Cost Factors

• Minimal Excavation – No soil removal means lower disposal and preparation costs.
• Faster Installation – Installation is quicker than bored piers, reducing labour costs.
• Material Costs – Typically lower than concrete, but specialized steel piles can increase costs.
• Versatility – Works well in various soil conditions, even in soft or waterlogged areas.
• Less Equipment – Requires a smaller crew and lighter machinery than bored piers.

Estimated Cost Range

Generally, it ranges from $80 - $600 per linear meter, depending on pile size and soil conditions.

Indicative Cost Comparison Summary

Factor	Bored Piers	Screw Piling
Installation Time	Slower	Faster
Excavation	Required	Minimal
Material Costs	High (Concrete & Steel)	Moderate (Steel Piles)
Labour Costs	Higher	Lower
Site Disruption	Higher	Lower
Weather Impact	Delays Possible	Minimal Impact
Overall Cost	$350 - $800/m	$80 - $600/m

Which Option Is Right for Your Project?

If your project demands a high load-bearing and lateral load capacity, bored piers may be the best choice despite their higher cost. However, if speed, cost savings, and minimal site disruption are priorities, screw piling is often the more economical solution.

At Koble Constructions, we specialize in foundation solutions tailored to your specific needs. Contact us today for expert advice and a detailed cost estimate for your project.

Reactive soils and the role of screw piles.

What are reactive soils, and what measures can be created to overcome them?

Reactive soil, or expansive soils are types of soil that change significantly in volume as the moisture content varies. When soil absorbs water, the soil expands causing a phenomenon called Heave to structures founded in reactive soil. Essentially pushing structures such as concrete slabs up when reactive soils are wet and receding below the concrete slab when the soil dries. Usually caused by changes in the seasons and now amplified by weather systems such as El Nino, La Nina and the Indian Ocean Dipole. Reactive soils present a challenge for designer’s builders and owners. Screw piling presents us with an economical solution to the confronts of reactive soils.

Typical types of reactive soils

Clay: High clay content is the primary characteristic of reactive soil. Clays absorb high amounts of moisture, causing a considerable amount of volume expansion.

Silt: can also exhibit reactive properties, although to a lesser extent than clay.

How do reactive soils affect structures?

When foundations are founded on or into reactive soils. The load path from the building structure to its foundation expands and contracts. The movement of the building structure from its foundation is often uneven and can cause considerable asset damage.

Methods to combat reactive soils using a Geotechnical report.

Establishing the depth of reactive soils is the first step to designing a suitable foundation for a structure. A Geotechnical report (soil report) is used by an engineer to determine a solution for reactive soils. The Geotechnical report shows the type, depth and moisture content of soils below the ground surface. Often combined with local knowledge, a site specific geotechnical report aids the engineer at the design stage of the project. The appropriate foundation depth is typically at a depth below the ground surface, that has low moisture content and high load bearing capacity.

Why are screw piles Koble Constructions preferred choice for reactive soils

Steel screw piles are an excellent solution for reactive soils, particularly on challenging sites, as they can penetrate unstable, often waterlogged layers to reach solid founding material. Using screw piles is a reliable method that ensures strong foundations while preventing issues related to soil expansion and contraction. Koble Constructions prefer screw piling because it is the simplest, most cost-effective way to establish a foundation below the reactive soil line, providing fast reliable structural support while avoiding complications like soil collapse and the need for bulk concrete.

Koble Constructions. Reactive soil, screw pile foundation.

Screw pile cost blowout

Why were additional costs incurred?

You may be curious to know why Koble Constructions, an advocate for Screw piles, is writing about cost blowouts and the reasons for them.  The following is an interesting case study showing that, occasionally, cost blowouts happen, and it’s essential to understand how and why it can happen.

A client of Koble Constructions provided us with structural drawings and a soil report for a small building on a large block in the outer suburbs of Melbourne. In this case, the decision was made to use screw piles instead of bored piers because of limited access along the side of an existing building and to save construction time.

The soil report showed a soil founding depth of 2 - 2.5 meters deep, but groundwater was not encountered. The structural drawing specified screw piles to be a minimum of 2.5 meters deep with a minimum load-bearing capacity of 60Kn. Koble Constructions quoted that they would supply 3.0-meter-long 80Kn piles for the installation.

On the day of the installation, Koble Constructions arrived on site with a truck loaded with an excavator, screw piling auger drive motor, a torque measuring unit and the correct amount of 3.0 80 Kn screw piles to complete the job.

The screw piles were unloaded from the truck and positioned ready for installation. The operator drove the first screw pile into the ground, but the pile didn’t make the required torque. The same thing happened for every single screw pile on the rest of the site.

The question now was how deep the piles would need to go to meet the specified torque requirements. After some deliberation between Koble Constructions' ground crew and the builder, it was agreed that a set of 1.5-meter extensions should be added to the piles to reach the required depth to make the torque for 60 kn of load per pile. The pile extensions were added to the piles, but they still didn’t make the required load-bearing torque.

A second lot of extensions had to be installed. The soil report showed foundation material at 2 to 2.5 metres deep. So, what was going wrong?   Koble Constructions added an extra 1.0-metre pile extension, to an already 1.5-meter extended screw pile to see just how deep we had to go to make the required torque. The total depth needed was 5. 5 meters deep. A truckload of 1-meter screw pile extensions was ordered, plus an additional 10 1.0-meter spare screw piles, in case we had to go deeper in some locations.

In the end, five out of the 10 spare 1-metre screw pile extensions had to be used to make the required torque.  Screw pile total depths varied from 5.5 metres to 6.5 metres deep. An average depth of close to double the depth stated in the soil report.

There was no option but to screw the piles down deeper. If screw piles don’t make the design torque, the supported structure has a high chance of failing. Leading to cracking and the possibility of complete building failure. An unstable foundation is a disaster for the Designer, the Engineer, the Builder and the client.

The alternative was to use bored piers instead of screw piles. For this site, bored piers would have been an enormous challenge due to the excessive depth needed to reach the foundation material. The cost for bored piers would be at least twice the cost of screw piles. The cost of deep footings with blinding would be 4-6 times more expensive than screw piling. when you include concrete pumping and spoil removal.

The key takeaways from this case.

Soil reports don’t always indicate what is beneath the ground throughout the entire site. Screw piling for foundations is an excellent solution for dynamic ground conditions. The option to use extensions to reach a foundation depth makes screw piles our preferred solution. When the unexpected happens, screw piles are the most economical solution.