Helical pier underpinning is a fast, clean method for stabilising foundations on Adelaide’s reactive clay soils. If your home shows signs of settlement — cracking walls, sticking doors, uneven floors — and you want a fix that’s installed in days rather than weeks, helical piers are worth understanding.

Through ADL Underpinning, you can connect with licensed contractors who install helical pier systems across Adelaide’s metro area. This page explains how they work, when they’re the right choice, what they cost, and how they compare to similar methods.

What Are Helical Piers?

Helical piers are steel shafts fitted with one or more helical (spiral) plates near the tip. They’re screwed into the ground using a hydraulic drive head until the plates reach stable, load-bearing soil below the reactive clay layer. The pier is then connected to your existing footing via a steel bracket, transferring your home’s weight from the failing shallow soil to the competent ground below.

The concept is straightforward — imagine a large, engineered screw anchoring your house to solid ground beneath the problem soil. No excavation, no concrete curing, no waiting.

Helical Piers vs Screw Piles — What’s the Difference?

This is the most common question we get. Functionally, helical piers and screw piles use the same principle — helical plates screwed into the ground to reach bearing capacity. The distinction is mainly one of size and application:

Helical piers are typically smaller diameter (50–90mm shaft) with 200–350mm helical plates. They’re primarily used for residential underpinning and light commercial work
Screw piles tend to be larger (90–150mm+ shaft) with bigger plates, used for higher loads and new construction piling

In practice, the terms are often used interchangeably in the Australian market. What matters is that the pier is correctly designed for your building’s loads and soil conditions — not what it’s called.

Why Helical Piers Work Well in Adelaide

Adelaide’s reactive Keswick and Hindmarsh Clay soils are the leading cause of residential foundation damage in the metro area. These clays shrink in summer and swell in winter, creating a relentless cycle of soil movement that shallow foundations can’t withstand.

Helical piers bypass this problem entirely. They screw through the reactive layer — which can extend 2–4 metres deep in suburbs like Unley, Mitcham, and Burnside — and anchor into the stable soil or weathered rock beneath. Once your home’s weight is transferred to the piers, seasonal clay movement no longer affects the foundation.

Key advantages for Adelaide conditions:

No excavation — the piers are screwed in from the surface, so there’s no need to dig pits under your house
Immediate loading — unlike concrete methods, helical piers can bear load as soon as they’re installed. No curing time
Verifiable capacity — installation torque is monitored in real time, confirming each pier has reached adequate bearing soil
Low vibration and noise — safe for heritage buildings and properties with shared walls
Compact equipment — installation rigs fit through standard side passages and gates
All-weather installation — rain doesn’t delay the work since there’s no concrete to pour

When Are Helical Piers the Right Choice?

Your foundation is moving due to reactive clay shrink-swell cycles
You need a fast turnaround — installation is typically completed in 1–3 days
Access is limited (narrow side passages, established gardens, small backyards)
The building is structurally sensitive and can’t tolerate vibration from excavation or driven piles
You want a solution with immediate load capacity and no wait for curing
You’re preparing for a home extension and need to ensure existing footings can handle the additional load

When Helical Piers May Not Be Suitable

We always recommend the most appropriate method, even if it’s not the one you expected:

Rocky ground — if rock or dense calcrete sits close to the surface, the helical plates can’t screw through it. Micropiles (drilled and grouted) are better suited to rocky ground
Very heavy loads — for large commercial buildings or multi-storey structures, beam and base underpinning may provide the capacity needed
Minor localised settlement — if only a small section has dropped slightly, resin injection is faster and more cost-effective
Underground obstructions — old tree roots, buried concrete, or abandoned services can block helical plates. A site inspection will identify these issues upfront

The Helical Pier Installation Process

Assessment and engineering — we inspect the property, review soil reports, and work with a structural engineer to design the pier layout (number, spacing, depth, and plate configuration)
Service location — underground services are located and marked before any pier locations are confirmed
Pier installation — using a compact hydraulic drive head (typically mounted on a mini excavator or skid steer), each pier is screwed into the ground. Installation torque is monitored continuously to confirm when the pier reaches competent soil
Bracket connection — steel brackets are fitted between the pier heads and the existing footing, creating a direct load path from your house to the deep bearing soil
Relevelling (if needed) — hydraulic jacks are used to carefully lift the foundation back toward level before the brackets are locked off
Engineer certification — the structural engineer inspects the completed installation and issues compliance documentation

Most residential helical pier jobs in Adelaide are completed in 1–3 days.

Helical Pier Underpinning Costs in Adelaide

Helical pier costs are generally mid-range among underpinning methods. Typical Adelaide pricing:

Minor stabilisation (one wall, 4–6 piers): $4,000–$10,000
Standard residential (perimeter, 8–16 piers): $10,000–$25,000
Full house with relevelling (16+ piers): $25,000–$40,000+

Cost varies based on pier size and depth, number of piers, access conditions, and whether relevelling is included. Our partner contractors provide fixed-price quotes after our site inspection — no surprises.

For an initial estimate, use our cost calculator or request a free quote.

Common Questions About Helical Piers

How long do helical piers last?

Helical piers are manufactured from galvanised or epoxy-coated steel designed for permanent installation. In Adelaide’s soil conditions, a properly installed and coated pier has a design life of 75+ years.

Will helical piers fix my cracks?

Helical piers stop the foundation from moving further and can lift it back toward level. Existing cracks will need to be repaired separately (by a plasterer or bricklayer), but they shouldn’t get worse once the piers are in place.

Do I need council approval?

Most residential underpinning in Adelaide doesn’t require a development application, but structural work does require a building rules consent from a private certifier. Our partner contractors handle the documentation and engineer certification — you’ll receive a full compliance pack when the job is complete.

Get Your Foundation Assessed

Foundation problems don’t pause — every dry Adelaide summer and wet winter drives more movement through your reactive clay soil. The earlier you act, the simpler and more affordable the fix.

Email chris@adlunderpinning.com with photos of the damage. We’ll review them within 24 hours and let you know whether helical piers are the right approach — or suggest a better option if one exists. No pressure, no obligation.

Helical Pier Underpinning Adelaide