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Understanding Terminologies for Foundation Pile Projects

August 20, 2025

Confused by foundation pile terminology in Australia? Our guide explains helical piles, bored piers, and key terms in simple language for your building project.

Navigating the world of building foundations can be complex, filled with technical terms that sound like a foreign language. For many Australian projects, especially on sites with challenging ground, foundation piles are the go-to solution for ensuring long-term stability.

This guide simplifies the essential terminology, from different pile types like helical piles to the installation process. Understanding these concepts will empower you to have more confident conversations with your engineers and builders, ensuring your project is built on solid ground from the start.

What is a Foundation Pile and Why is it Used in Australia?

At its core, a foundation pile is a type of deep foundation.

Think of it as a long, slender column, made from materials like steel or concrete, that is installed deep into the ground. Its primary job is to bypass weak or unstable surface soils and transfer the building’s weight, or ‘load’, down to a stronger, more competent layer of soil or rock.

This provides a stable base and ensures the long-term structural support of the building above it.

The Importance of Helical Piles for Australian Soil Conditions

Australia is a continent of diverse and often challenging geology. Many residential and commercial areas are built on what are known as “problem soils.” Reactive clay soils, common across Adelaide, Melbourne, and Western Sydney, swell when they absorb moisture and shrink as they dry out, causing significant ground movement that can crack conventional foundations.

Coastal regions in Perth and Queensland often have loose, sandy soils that offer poor support. In these situations, standard shallow foundations are not sufficient.

Foundation piles provide an engineered solution by anchoring the building to stable ground far below the problematic surface layers.

Core Concepts: Pile vs. Pier vs. Foundation

What’s the Difference Between Piling and a Foundation?

This is a common point of confusion. The simplest way to think about it is that piling is a type of foundation. Foundations are broadly categorised into two groups: shallow and deep.

A shallow foundation, like a concrete slab-on-ground or a strip footing, sits near the surface and distributes the building’s load over a wide area. It relies on the strength of the immediate surface soil.

A deep foundation, which includes all types of piling, is used when the surface soil isn’t strong enough. It bypasses these weak layers to find support deeper in the earth. So, piling is a specific technique used to create a deep foundation system.

Understanding the Difference: Pile vs. Pier

In Australia, the terms ‘pile’ and ‘pier’ are often used interchangeably in general conversation, which can be confusing. While they serve the same function of transferring loads to deeper soil, there is a technical difference in how they are installed.

A pile is typically a pre-made element that is forced into the ground, displacing the soil around it. This includes driven piles (hammered in) and screw piles (screwed in).

A pier, most commonly a ‘bored pier’ in Australia, is formed by first removing soil. A hole is drilled or augured into the ground, a steel reinforcing cage is placed inside, and then it is filled with concrete.

It’s a soil-replacement method. For most homeowners, the specific term is less important than understanding the function and why an engineer has chosen a particular method for your property.

Common Types of Foundation Piles Used in Australia

Engineers select a pile type based on the project’s needs, site access, and the specific soil conditions identified in a geotechnical report.

Helical Piles (or Screw Piles)

Helical piles, also known as screw piles, are a modern and increasingly popular foundation solution in Australia. They consist of a central, high-strength galvanised steel shaft with one or more helix-shaped plates welded to it. Think of it as a giant, engineered screw.

They are installed using hydraulic machinery that rotates the pile into the ground with no hammering and minimal site disturbance.

The installation torque is monitored in real-time, which allows engineers to verify the load-bearing capacity of each pile as it is installed.

Their key benefits include rapid pile installation, no curing time for concrete, and suitability for sites with limited access or environmental sensitivity. This makes helical piles Australia a leading choice for residential homes, extensions, and foundation repair Australia.

Driven Piles (or Displacement Piles)

Driven piles are prefabricated columns, often made of precast concrete, steel, or timber. As the name suggests, they are installed by being hammered or ‘driven’ into the ground with a large hydraulic hammer or pile driver.

This process displaces the surrounding soil. They are very effective at reaching great depths and can support heavy loads, making them common in large civil engineering projects like bridges and high-rise buildings.

However, the process generates significant noise and vibration, which can be a problem in established residential areas.

Bored Piles (or Replacement Piles)

Bored piles, or bored piers, are one of the most traditional forms of deep foundations in Australia.

The process involves using a large auger to drill a deep, cylindrical hole into the ground. A steel reinforcement cage is then lowered into the hole, which is subsequently filled with wet concrete.

They are excellent for supporting very heavy structures and can be installed without the vibration of driven piles. The main drawbacks are the need for heavy machinery and the time required for the concrete to cure before it can take any load.

Comparing Pile Types: Screw Piles vs Concrete Piles

For most residential and light commercial projects in Australia, the choice often comes down to screw piles vs concrete piles (specifically bored piers). Screw piles offer significant advantages in speed; an entire house foundation can often be installed in a day or two, whereas bored piers require time for drilling, pouring, and curing.

Steel screw piles also produce no soil spoils to be removed from the site, making for a cleaner and often more cost-effective installation. While bored piers are excellent for extremely heavy loads, the versatility, speed, and verifiable capacity of helical piles make them the preferred choice for a vast range of modern construction projects.

Key Terminology in the Piling Process

Understanding the language used during a piling project helps you follow the process and appreciate the engineering involved.

Geotechnical Report (or Soil Report)

This is the foundational document for any piling project. A geotechnical engineer will take soil samples from your site and perform tests to determine the different soil layers, their strength, and other characteristics.

The Geotechnical Report provides the essential data your structural engineer needs to design the most appropriate and cost-effective foundation systems, specifying the right pile type, depth, and required load-bearing capacity.

Load-Bearing Capacity

This term refers to the maximum weight or force that a single pile or the entire piling system can safely support. It is a critical calculation based on the pile’s design and the soil conditions outlined in the geotechnical report.

For helical piles, the capacity is directly correlated to the installation torque, providing a high degree of certainty during the installation itself.

Pile Cap

A pile cap is a thick, reinforced concrete block or beam that sits on top of one or more piles. Its job is to group the piles together and create a single, solid base. The building’s stumps, columns, or structural walls then sit on top of the pile cap, which evenly distributes their load onto the piles below.

Underpinning

Underpinning is the process of strengthening an existing building foundation that has failed or is showing signs of settlement (like major wall cracks). Helical piles are an ideal solution for underpinning because they can be installed in tight spaces right next to the existing structure with minimal vibration.

The piles are screwed into the ground until they reach a stable stratum, and brackets are then used to connect them to the existing footing, lifting and re-levelling the structure if necessary.

Australian Standards and Engineering Certification

All piling work in Australia must comply with strict regulations, including the Building Code of Australia and specific industry standards like AS 2159 – Piling – Design and installation. This ensures safety and quality.

Any piling system must be designed by a qualified structural engineer, and upon completion, the installer and engineer provide certification that the work was carried out according to the specified design.

Glossary of Common Helical Pile Foundation Terms

Auger: A drilling tool with a helical blade used to excavate soil, primarily for bored piers.
Battered Pile: A pile installed at an angle to the vertical to resist lateral or horizontal forces, such as from wind or retaining walls.
Deep Foundation: A type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does. All piles are types of deep foundations.
Displacement Pile: A pile that displaces soil as it is installed rather than removing it. Driven piles and screw piles are displacement piles.
Geotechnical Engineer: A civil engineer who specialises in the behaviour of earth materials and soil conditions.
Helix/Helical Plate: The circular, screw-like plate welded to the shaft of a helical pile. It is responsible for pulling the pile into the ground and providing the bearing surface.
Load: The force or weight exerted on the foundation by the building and its contents.
Pile Cap: A concrete block that transfers the building load from a column or wall to a group of piles.
Reactive Soil: Clay-based soils that swell and shrink significantly with changes in moisture content, a common issue in many parts of Australia.
Screw Pile: The common industry term for a helical pile.
Settlement: The downward movement or sinking of a building’s foundation, often caused by poor soil or inadequate foundation design.
Shallow Foundation: A foundation that transfers building loads to the soil very near the surface (e.g., a concrete slab).
Shaft (of a pile): The central steel tube or core of a helical pile.
Spoils: The excess soil and earth removed during excavation, typically associated with bored piers.
Structural Engineer: An engineer who designs the structural elements of a building, including the foundation, to ensure it can safely support the loads.
Torque: The rotational force applied by the machinery to install a helical pile. It is a direct measure of soil resistance and is used to verify the pile’s load-bearing capacity.
Underpinning: The process of installing new foundation elements, like helical piles, to support an existing, failing foundation.

Understanding Foundation Pile Terminology in Australia

Gaining a basic grasp of foundation terminology like helical piles, load-bearing capacity, and underpinning is the first step toward a successful building project.

While the terms can seem technical, they all relate to one simple goal: creating safe, reliable, and lasting structural support for your property.

This knowledge allows you to ask informed questions and better understand the recommendations of your engineer.

For any foundation work, always partner with experienced professionals who can explain these concepts clearly and deliver an engineered solution.

Ensuring your foundation is correctly designed and installed for Australian conditions is the best investment you can make in your property.

Frequently Asked Questions About Foundation Pile Terminology in Australia

What Are the 3 Types of Piling?

In Australia, the three main categories of piles you will encounter are driven piles (hammered into the ground), bored piles (or piers, where a hole is drilled and filled with concrete), and helical piles (also known as screw piles, which are screwed into the ground). Each has specific applications depending on the load requirements, soil type, and site conditions.

What Is the Difference Between a Pier and a Pile?

While often used interchangeably, technically a pile displaces soil as it is installed (like a driven or screw pile), whereas a pier is typically constructed by removing soil first (by drilling a hole) and then filling it with concrete. In practice, both serve the function of a deep foundation element to support a structure.

What Is the Piling Process in Construction?

The piling process follows a structured engineering sequence. It starts with a geotechnical (soil) investigation, followed by an engineer’s design specifying the pile type, depth, and layout. The site is then prepared, pile locations are marked, and the piles are installed using specialised machinery. Finally, they are trimmed to height and capped, ready for the building structure, with all work being certified.

What Is the Difference Between Piling and Foundation?

Piling is a type of foundation. A foundation is the general term for the base of a structure, which can be either shallow (like a slab) or deep. Piling is a method used to create a deep foundation, necessary when the shallow soils are not strong enough to support the building.

Why Is Piling So Expensive?

Piling involves specialised engineering design, geotechnical testing, heavy machinery, and skilled labour, which contributes to the cost. The materials, such as high-strength steel or large volumes of concrete, are also significant expenses. However, the cost should be weighed against the alternative: the far greater expense of repairing a failed foundation and the structural damage it causes to a building.

How Do You Know if You Need Piling?

You will likely need piling if your construction is on a site with problematic soil conditions, such as highly reactive clay, soft or loose sand, or filled land. Signs that piling may be required include recommendations in a geotechnical report, building on a steep slope, or visible signs of major cracking or settlement in neighbouring properties. Ultimately, a structural engineer will make the final determination based on soil tests and your building plans.