Calculating Torque and Load for Screw Piles: A Practical Guide

When it comes to designing reliable foundations, understanding the relationship between installation torque and load capacity is essential. At ABC Anchors, this forms a key part of ensuring every screw pile performs exactly as required - whether for a garden room or a large structural build.

But what does torque really tell us? And how do we translate that into safe, working load?

Let’s break it down.

What Is Torque in Screw Piling?

Torque is the rotational force used to install a screw pile into the ground. As the pile is driven deeper, resistance increases - and this resistance is measured as torque (typically in kNm).

Unlike traditional foundations, screw piles are installed using hydraulic torque motors rather than hammering or vibration, resulting in a smooth, controlled installation process with minimal disturbance .

Put simply:

• Higher torque = stronger ground resistance

• Stronger ground resistance = higher load capacity

This is why torque is one of the most valuable real-time indicators during installation.

Why Torque Matters

Torque isn’t just a number on a gauge - it’s a direct indicator of how your pile will perform.

During installation, achieving the correct torque ensures:

• The pile has reached suitable bearing strata

• The foundation can safely support the required loads

• The installation meets engineering specifications

Because screw piles derive their capacity from both end bearing (helix plates) and shaft friction, monitoring torque gives a reliable insight into both mechanisms working together .

The Torque to Load Relationship

One of the most widely used principles in screw piling is the correlation between torque and load capacity.

This is typically expressed as:

Ultimate Capacity (Qu) = Kt × T

Where:

• Qu = ultimate load capacity (kN)

• Kt = empirical torque factor

• T = installation torque (kNm)

This relationship is widely used in the industry and referenced in screw pile design guidance .

What is the Torque Factor (Kt)?

The Kt factor depends on several variables, including:

• Soil type and density

• Pile diameter and shaft design

• Helix configuration

• Installation method

Because of this, Kt is usually determined through site testing or experience, rather than assumed blindly.

Compression vs Uplift Loads

Screw piles are uniquely capable of handling both:

Compression Loads

• From structures pushing downward

• Common in buildings, extensions, and slabs

Uplift (Tension) Loads

• From wind, overturning forces, or buoyancy

• Critical in structures like canopies, solar arrays, and retaining systems

By correlating torque with capacity, engineers can verify that the pile is suitable for both loading scenarios.

Factors That Affect Torque and Load

Several key variables influence the torque you’ll achieve - and therefore the load capacity:

1. Ground Conditions

Clay, sand, gravel, and made ground all behave differently. Denser soils typically generate higher torque.

2. Pile Type

Different pile sizes (e.g. 60R, 76R, 89R) have varying torque limits and load capacities, typically ranging from around 4 kNm up to 22.5 kNm depending on the system .

3. Installation Equipment

Using the correct torque head ensures accurate readings and consistent installation.

4. Depth of Installation

Deeper piles often reach stronger strata, increasing torque and capacity.

Why Calculating Torque and Load Matters for Your Project

Getting the torque vs load relationship right means:

• No over-engineering (saving cost)

• No under-performance (ensuring safety)

• Faster installation with immediate load-bearing capability

Unlike concrete, screw piles don’t rely on curing time- so once the correct torque is achieved, your foundation is ready to go.

How ABC Anchors Supports You

At ABC Anchors, we don’t just supply screw piles - we help you understand how they perform.

We can support you with:

• Test pile kits to assess ground conditions

• Torque monitoring during installation

• Guidance on selecting the right pile and equipment

• Training on installation and best practices

Our goal is simple: to give you confidence in your foundation from the ground up.

Final Thoughts

Torque is more than just a measurement - it’s the link between installation and performance.

By understanding how torque translates into load capacity, you can ensure your screw pile foundation is:

• Safe

• Efficient

• Built to last

If you’re planning a project and want expert advice on torque, load calculations, or pile selection, get in touch with the ABC Anchors team.