Underpinning Adelaide - Licensed Foundation Repair Specialists
Concrete underpinning, engineered solutions, backed by a 10-year guarantee.
Licensed Builder
Fully Insured
25+ Years Experience
10-Year Guarantee
Trusted Underpinning Contractors Across South Australia
When your foundation moves, the cracks in your walls are only the visible part of the problem. Underneath them, the soil that’s meant to support your home has shifted, settled, or subsided, and the only permanent fix is a structural one.
AllenCo Construction is a licensed foundation contractor providing underpinning across Adelaide and South Australia. We’ve been underpinning Adelaide homes for over 25 years, using reinforced concrete bored piers, proper soil testing, and an engineered approach to stabilise homes affected by subsidence, reactive clay soil and foundation movement.
When You Need Underpinning
You need underpinning when the soil beneath your home shifts, settles, or subsides, causing the foundation to move. There are 4 main causes of foundation movement in Adelaide homes, and the sooner the cause is identified, the more cost-effective the foundation repair becomes.
Reactive Clay Soil
Plumbing Leaks Under Footings
Tree Roots Drawing Moisture
Soil Erosion Under Footings
Poor drainage, sloping sites, or burst pipes wash away the soil supporting the footings, leaving sections of your foundation unsupported.
Signs You Need Underpinning
You need underpinning when foundation movement starts showing visible damage to your home. There are 6 common signs that point to subsidence or foundation failure, and they rarely fix themselves. The structural damage gets harder and more expensive to repair the longer it’s left.
The quickest way to know for sure is to book a free on-site inspection. We come to you, assess the cracks, and tell you honestly whether your home needs underpinning or whether a smaller fix will do.
Why Choose AllenCo Construction
Licensed Builder, Fully Insured
Award-Winning Builder
25+ Years Building Across SA
10-Year Guarantee
What Our Customers Say
How It Works
Every underpinning job we take on follows the same steps, so you know exactly what to expect and what comes next.
1. Free Quote
2. Excavation
3. Underpin Installation
4. Rectification
AllenCo Construction's Preferred Underpinning and Foundation Repair Method
The most effective methods for underpinning a house are screw piles, concrete bored piers, and mass concrete pours. The right method depends on the soil conditions, the type of home, and the extent of the foundation movement.
At AllenCo Construction, we use reinforced 4-metre concrete bored piers. We excavate beneath the original footings, then pour concrete and reinforce it with steel for strength, structural integrity, and proper load distribution. The piers extend deep enough to reach stable ground, well below the influence of reactive clay soil and the seasonal moisture changes that cause foundation movement.
Once the concrete has cured, heavy-duty hydraulic jacks lift your house back into position, closing the cracks and voids opened by years of subsidence. The structure is then locked in place with heavy-duty props or further steel-reinforced concrete to make the repair permanent.
Because the piers reach stable ground at four metres, the result is a permanent foundation underpinning repair, backed by our 10-year guarantee.
Engineered Underpinning, Not Guesswork
Foundation repair is one of the most consequential structural decisions a homeowner can make. It’s not a place for shortcuts, trial and error, or trialling the latest unproven techniques. The concrete underpinning methods we use have been refined over decades, battle tested across thousands of South Australian homes on reactive clay, water-damaged foundations, and sites with serious subsidence.
Every job we quote begins with 3 stages of proper diagnosis:
Soil Test
CCTV Drainage Inspection
Engineer's Report
A structural engineer specifies the pier depth, load distribution, and underpinning layout required for your site and your home.
Only then do we lift a tool. The result is an engineered solution, designed for your home, applied by a licensed builder, and monitored from the first inspection through to the final coat of paint. No guesswork. Just work that holds up.
Underpinning FAQs
What is underpinning?
Underpinning is the process of extending and reinforcing the existing footings of a home so they reach stable, load-bearing ground. It’s used to fix foundations that have moved due to soil movement, subsidence, plumbing leaks, or tree root damage. Done properly, it’s a permanent structural repair.
How long does underpinning take?
Most residential underpinning jobs take between 1 and 3 weeks on site, depending on the number of piers required and the condition of the home.
How much does underpinning cost?
The cost of underpinning is between $5,000 and $40,000. The final cost depends on the number of piers required, the soil conditions, the depth needed to reach stable ground, and the extent of the rectification works that follow. We provide free on-site quotes based on what your home actually needs.
Do I need council permits for underpinning?
You need council permits for most underpinning jobs in South Australia. We handle all council permits and the relevant building consents as part of the job, so you don’t have to.
Is underpinning permanent?
Reinforced concrete pier underpinning is a permanent structural repair. Because our piers extend to stable ground at 4 metres, they sit below the influence of seasonal soil movement and reactive clay conditions. Our work is backed by a 10-year guarantee.
Can underpinning fix cracked walls?
Underpinning stabilises the foundation and, in most cases, lifts the structure back toward its original position, closing existing cracks in the process. The wall crack repairs that follow (crack stitching, re-pointing, re-rendering) form the rectification stage of the job. AllenCo handles both stages in-house.
Get Your Underpinning Done Properly
Join hundreds of South Australian homeowners who’ve stabilised their foundations with AllenCo Construction.
Free quote. Licensed builder. Custom workmanship.
*Cracks getting wider? Doors sticking? Floor dipping in the middle of the room? Don’t guess at the cause, get a proper diagnosis. We come to you, inspect your home or property, arrange the necessary drainage and engineering reports, and give you a clear, accurate quote.