How much does foundation repair cost?

Most foundation repairs range from $4,000 to $16,000, depending on the extent of the damage and the size of your property.

How long does the repair take?

Most foundation repairs are completed in just 1-2 days using our GeoPoly™ resin injection method.

What is GeoPoly™ resin injection?

GeoPoly™ is a high-strength expanding resin that we inject beneath your foundation. As it expands, it fills voids, compacts loose soil, and lifts your foundation back to level.

Will you need to dig up my yard?

No! We drill small holes (about 16mm diameter) through your slab or beside your footings, inject the resin, and patch the holes. No excavation required.

What does the 20-year warranty cover?

Our 20-year structural warranty covers the repair work we perform. If any issues arise with the repaired area due to workmanship or materials, we'll fix it at no additional cost.

Is the assessment really free?

Yes, 100% free with no obligation. Our structural engineer will inspect your property, explain the issues, and provide recommendations.

What is underpinning and when is it needed?

Underpinning is the process of strengthening and stabilising a building’s existing foundations. It’s needed when footings can no longer support the structure above — usually because the soil underneath has shrunk, washed away, or compacted over time. Common signs include cracking walls, sticking doors and windows, sloping floors, and visible gaps between walls and ceilings. If your home is showing any of these symptoms, a free structural assessment will confirm whether underpinning is required.

What are the signs my home needs underpinning?

The most common indicators are diagonal cracks near doors and windows, doors or windows that no longer close properly, uneven or sloping floors, gaps opening between walls and ceilings or floors, and one side of the home visibly lower than the other. These symptoms usually mean the soil beneath your footings has moved, and the foundation is no longer level. Our structural engineers can confirm the cause during a free on-site assessment.

How does resin underpinning differ from traditional concrete underpinning?

Traditional concrete underpinning involves excavating beneath your footings and pouring mass concrete piers — a process that typically takes weeks, requires heavy machinery, and disrupts your garden and driveway. GeoPoly™ resin underpinning uses small injection points (about the size of a 20-cent coin) to deliver geopolymer resin 2+ metres beneath your footings. The resin fills voids, compacts weakened soil, and works to bring your home back towards level with laser-guided precision — typically in just 1–2 days, with no excavation and no concrete curing time.

How does GeoPoly™ resin underpinning work?

Our team drills small injection points through the slab or alongside your footings. GeoPoly™ GER60 geopolymer resin is then injected 2+ metres beneath the foundations. As the resin expands, it fills voids in the soil, compacts weakened ground, and works to gradually lift the foundation back towards level. The entire process is controlled in real time using laser monitoring equipment, so we can manage every millimetre of the lift without putting stress on the structure above. Your engineer will explain exactly how much improvement is achievable for your property.

How much does underpinning cost?

Every home is different, so we provide a fixed-price quote after your free structural assessment. The cost depends on the extent of the subsidence, the size of the affected area, and the soil conditions beneath your property. There are no hidden costs or surprise charges — the price we quote is the price you pay. Our engineer can usually give you a price indication on the day of the assessment. In most cases, resin underpinning is significantly less expensive than traditional concrete underpinning because there’s no excavation or heavy machinery involved.

How long does resin underpinning take?

Most residential underpinning jobs are completed in one to two days, depending on the extent of the subsidence and the size of the affected area. There’s no excavation, no concrete curing time, and no heavy machinery — so the turnaround is significantly faster than traditional concrete underpinning, which can take weeks. Your engineer will confirm the expected timeframe during your free structural assessment.

Do I need council approval for underpinning?

In most cases, no. GeoPoly™ resin injection is classified as maintenance work and typically does not require a building permit or council approval. This is another advantage over traditional concrete underpinning, which often requires engineering certification and council sign-off before work can begin. If your situation is an exception, we’ll let you know during the assessment and help with any paperwork needed.

What does the 20-year warranty cover?

Our 20-year warranty covers both the GeoPoly™ product and our workmanship. If anything we’ve underpinned moves again within that time, we come back and make it right — at no cost to you. The warranty is attached to the property, not the owner, so it transfers automatically if you sell your home. This can add value to your property and give buyers extra confidence.

Can I stay in my home during the underpinning?

Absolutely. GeoPoly™ injection is non-invasive — there’s no excavation, no heavy machinery, and no structural demolition. The work is carried out from small injection points around the perimeter or through the slab, so you and your family can stay home throughout the process with minimal disruption to your daily routine.

Does resin underpinning work on reactive clay soils?

Yes. Reactive clay is one of the most common causes of foundation movement across Melbourne, Sydney, and Canberra. The clay swells when wet and shrinks when dry, causing the ground to constantly expand and contract. GeoPoly™ resin injection fills the voids created by this movement, compacts the soil beneath your footings, and stabilises the foundation. In cases of severe reactive clay, we may also recommend control joints or drainage improvements to manage ongoing soil moisture — our engineer will explain the best approach during your free assessment.

Quoted for Underpinning? Read This First.

Find the cause, stabilise your foundations, and bring your home back towards level with resin underpinning \u2014 no excavation, guaranteed for 20 years.

Free quote · 1–2 day repair · 20-year warranty
Structural Engineers · Licensed Builders · Skilled Technicians

Been Told Your Home Needs Underpinning?

Find the cause, stabilise your foundations, and bring your home back towards level with resin underpinning \u2014 no excavation, guaranteed for 20 years.

Free structural assessment with a fixed-price quote
No excavation — most jobs completed in just 1–2 days
Backed by a 20-year warranty

Qualified Engineers · Licensed Builders

15,000+Homes Repaired

20-YearStructural Warranty

1–2 DaysMost Repairs

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There's a Way to Do This Without Digging Up Your Home.

Non-Invasive. Precision-Controlled. Guaranteed.

No Excavation. No Concrete Piers. No Weeks of Disruption.

If you've been quoted for traditional underpinning — trenches dug around your home, mass concrete poured beneath the footings, heavy machinery on your property for weeks — that's one way to do it. It works. But it's slow, expensive, and turns your home into a building site. There's a smarter way that costs less, finishes faster, and doesn't destroy your garden in the process.

GeoPoly™ resin underpinning works through small, coin-sized injection points — no excavation, no trenches, no concrete. Engineered resin is injected 2+ metres beneath your footings, expanding to fill voids and compact weakened soil. Laser monitoring tracks every millimetre of movement in real time as the foundation is gradually lifted back towards level. That's it. No machinery. No curing time. No mess.

The whole job typically takes a day or two — at a fraction of the cost of traditional concrete underpinning. When it's done, the drill holes are patched and your property looks exactly as it did before. Except now the foundations are stable, level, and guaranteed for 20 years.

Wondering if resin underpinning is right for your home? The free assessment answers that. Get in touch — no obligation.

What to expect

Here’s how we underpin your home’s foundations, from first visit to warranty.

Buildfix structural engineer assessing foundation subsidence with laser level equipment

Step 1

Free Structural Assessment

One of our qualified engineers assesses the subsidence, identifies the root cause, and designs a tailored solution. Repair details — with photos, markings, and measurements — are created on-site using our mobile software, and the price can usually be explained there and then, so you know exactly where you stand.

Buildfix quote package showing structural repair detail, quote cover page, and repair method statement

Step 2

Get Quote and Book

You receive a complete quote package including detailed drawings, repair method statements, and a fixed-price quote — so you’ll know exactly what it’s going to cost. When you’re ready, book through our online portal (takes about 5 minutes) and we’ll organise suitable dates for the work.

Buildfix technician drilling small coin-sized access holes for GeoPoly™ injection

Step 3

Drill for Access

Small, coin-sized holes are drilled at precise intervals around the problem areas. These allow our injection pipes to reach the exact depths needed beneath your foundation.

Buildfix technicians injecting GeoPoly™ resin beneath foundations

Step 4

Inject, Lift, and Level

GeoPoly™ resin is injected through the access points. The resin expands to fill voids and weak spots, then lifts and re-levels your foundation. Laser levelling equipment and digital sensors monitor every millimetre of movement in real time — so the lift is precise, controlled, and exactly right.

Patched drill holes after GeoPoly™ subsidence repair with clean site

Step 5

Patch and Clean Up

Once the foundation is stabilised and level, we patch the drill holes and clean up. Your home looks exactly as it did before we arrived — except now it’s on solid ground.

Step 6

Receive Your Warranty

A few days after sign-off, you’ll receive your Completion Package — a full report covering the work carried out, materials used, and images from the process. It includes your invoice with links to pay through our portal, and your 20-year warranty documentation. That’s your peace of mind, in writing.

See the difference

Actual GeoPoly™ projects where foundations are permanently stabilised.

Brick wall subsidence crack before and after GeoPoly repair

Foundation subsidence before and after re-levelling

Subsidence crack in render before and after repair

Sunken foundation before and after GeoPoly injection

Subsidence damage to brickwork before and after repair

Foundation settlement before and after re-levelling

Brick wall separation from subsidence before and after repair

Subsidence crack repair before and after

Foundation subsidence before and after stabilisation

Brick wall subsidence before and after GeoPoly repair

Instant results.
Guaranteed to last.

The benefits of GeoPoly™ resin underpinning.

GeoPoly™ resin is injected beneath your footings and monitored in real time with laser levelling equipment. Every millimetre of the lift is controlled — the same precision approach used to re-level CSIRO’s own research buildings to within 2mm tolerance.

GeoPoly resin injection beneath brick house with laser levelling equipment monitoring precision

Real homes. Real results

See how we’ve helped homeowners stabilise their foundations.

Why choose Buildfix?

Buildfix brings qualified engineers, licensed builders, skilled trades, and the manufacturer together under one roof. One team accountable for every step — from assessment to final sign-off. For nearly 15 years, we've been delivering non-invasive structural repairs — saving homeowners the hassle and costs of traditional methods. What used to take weeks now takes just 1 to 2 days.

Here’s why homeowners choose us

20-year warranty: Every repair is backed by a 20-year warranty — transferable if you sell your home.

Under one roof: We assess, design, repair, and manufacture — no need to deal with multiple contractors, because we handle it start to finish.

Fixed pricing, honest advice: No surprises, no tricks — just one fixed price from the start that never changes.

Non-invasive technology: Every method we use is non-invasive — less mess, less stress, and most repairs done in 1 to 2 days.

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Questions?

We are here to answer any questions you may have Monday – Friday 8am to 4pm AEST. Give us a call on 1300 854 115.

Quoted for Underpinning? Read This First.

Been Told Your Home Needs Underpinning?

Don't take our word for it

There's a Way to Do This Without Digging Up Your Home.