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.

Why are my house floors sinking?

Indoor concrete slab floors sink when the soil beneath them weakens, compacts, or washes away — creating voids under the slab. Common causes include reactive clay soils that shrink in dry weather, poor compaction when the house was built, leaking pipes washing soil away beneath the slab, and tree roots drawing moisture from the ground. The slab itself is usually fine — it's the ground underneath that's moved.

What are the signs of a sinking floor?

The most common signs include cracked floor tiles or grout lines, gaps opening between the skirting boards and the floor, doors that no longer close properly or drag on the floor, a visible slope or dip you can feel when walking across the room, and cracks appearing in walls near the affected area. If you're noticing any of these, it's worth getting a free structural assessment to find out what's happening beneath the slab.

How does GeoPoly™ re-level a slab from underneath?

We drill small injection points through the slab — each about the size of a 20-cent coin. GeoPoly™ GER60 resin is then injected beneath the concrete, where it expands to fill voids and compact weakened soil. As the resin builds pressure, it gradually lifts the slab back to level. The entire process is monitored with real-time laser equipment so we can control every millimetre of the lift.

Why shouldn't I just use self-levelling cement?

Self-levelling cement is a surface-level fix — it adds a layer on top of the slab to even out the surface, but it doesn't address why the floor sank in the first place. The voids and weakened soil beneath the slab are still there, and the floor can continue to move over time. The added weight of the cement can even make things worse. GeoPoly™ takes a different approach — it fills those voids and stabilises the soil from underneath, so you're addressing the cause rather than covering it up.

How much does floor relevelling cost?

Every home is different, so we provide a fixed-price quote after your free structural assessment. 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, so you know where you stand before committing to anything.

How long does slab relevelling take?

Most indoor slab relevelling jobs are completed in a single day. Larger areas or more severe sinking may take up to two days. There's no concrete curing time and no drying period — the resin sets quickly, so you can walk on the floor the same day. Your engineer will confirm the expected timeframe during your free assessment.

Will my tiles crack during the relevelling?

We take great care to minimise the risk to tiles. The lift is controlled gradually using real-time laser monitoring, which means the slab rises slowly and evenly — rather than being forced up in one go. In most cases, tiles come through the process without any new damage. However, if tiles are already cracked or loosely bonded, we'll flag that during the assessment so there are no surprises.

How long does a GeoPoly™ floor relevelling last?

GeoPoly™ is a geopolymer resin — it doesn't shrink, dissolve, or break down in the ground. Once injected, it fills voids and locks the compacted soil in place. It's the same technology we used to stabilise CSIRO's research buildings, and every repair is backed by our 20-year warranty. That said, soil conditions vary from property to property — your engineer will explain exactly what to expect during the assessment.

What does the 20-year warranty cover?

Our 20-year warranty covers both the product (GeoPoly™ resin) and the workmanship. If anything we've repaired moves again within that period, we come back and make it right at no additional cost. The warranty is attached to the property, not the owner — so it transfers automatically if you sell your home.

Can you fix just one room, or does the whole slab need doing?

We can target individual rooms or specific areas of the slab — you don't need to treat the entire house. During the free assessment, our engineer will identify exactly which areas have sunk and where the voids are, so the repair is focused only on the sections that need it. That keeps the cost down and the disruption to a minimum.

Floor Slabs Sinking Inside Your Home?

GeoPoly™ resin injection re-levels your slab from underneath — not with self-levelling cement on top. The cause is fixed, the floor is level, and the repair is guaranteed for 20 years.

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

Floor Slabs Sinking Inside Your Home?

GeoPoly™ resin injection re-levels your slab from underneath — not with self-levelling cement on top. The cause is fixed, the floor is level, and the repair is guaranteed for 20 years.

Free structural assessment with a fixed-price quote
Most indoor floor relevelling completed in just one day
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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Don't take our word for it

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Pouring Cement On Top of a Sinking Slab Doesn't Fix What's Underneath.

Non-Invasive. Precision-Controlled. Guaranteed.

No Self-Levelling Cement. No Tiles Removed. No Guessing.

If your indoor floors are dipping, sloping, or pulling away from skirting boards — the slab is moving. The ground beneath it has settled, compacted, or washed away. Pouring self-levelling cement on top adds weight to an already sinking surface and doesn't touch the problem underneath. When the ground keeps moving, the cement cracks too.

GeoPoly™ fixes the cause. Resin is injected through small holes in the slab — directly into the ground beneath — filling voids, compacting weakened soil, and gradually lifting the slab back towards level. Laser monitoring tracks every millimetre of the lift in real time. No tiles are removed. No cement is poured on top. The floor is re-levelled from underneath, where the problem actually is.

Most indoor slab relevelling jobs are finished in a single day. Your floors are level, your tiles are intact, and the cause — not just the symptom — has been fixed. Guaranteed for 20 years.

Not sure what's causing your floors to sink? That's what the free assessment is for. Get in touch — no obligation.

What to expect

Here’s how we re-level your home’s sinking floors, from first visit to warranty.

Buildfix structural engineer assessing foundation movement with laser level equipment

Step 1

Free Structural Assessment

One of our structural engineers checks floor levels, inspects the slab, and identifies what's causing the sinking — whether it's soil settlement, washout, or compaction beneath the concrete. A tailored GeoPoly™ repair is designed on the spot.

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

Step 2

Get Quote and Book

A complete quote package with drawings, method statements, and a fixed-price quote. Book through the online portal when you're ready.

Buildfix technicians injecting GeoPoly™ resin beneath indoor concrete slab to fill voids and lift the floor

Step 3

GeoPoly™ Injection

Small holes are drilled through the slab at precise intervals. GeoPoly™ resin is injected directly into the ground beneath the concrete — filling voids, compacting weakened soil, and creating a stable base for the slab to sit on.

Step 4

Lift, Level, and Verify

The slab is gradually lifted back towards level using laser-monitored precision. No tiles are removed. No self-levelling cement is poured on top. Your engineer confirms the results before the team leaves.

Step 5

Receive Your Warranty

The Completion Package arrives a few days after sign-off — a full report with images, invoice, and your 20-year warranty documentation.

See the difference

Actual GeoPoly™ projects where sinking floors are permanently re-levelled.

Gap beneath skirting board closed after indoor slab relevelling

Sunken brick wall foundation gap closed after slab lift

Gap under door frame on timber floor closed after slab relevelling

Sinking tiled floor at doorway relevelled back to skirting level

Cornice and ceiling gap above kitchen cabinet closed after slab lift

Sunken concrete slab at door threshold lifted back to brick wall

Sunken brick wall corner at fence line lifted back to level

Gap beneath skirting board on tiled floor closed after relevelling

Sunken concrete slab gap at brick wall measured and closed after lift

Sunken concrete slab gap at brick wall closed after relevelling

Instant results.
Guaranteed to last.

The benefits of GeoPoly™ floor re-levelling.

GeoPoly™ resin is injected beneath the concrete slab to fill voids and lift the floor back to level. This fixes the cause — the ground underneath — not just the surface. It’s not self-levelling cement poured on top of a sinking slab.

GeoPoly resin injected beneath concrete slab to re-level sinking floor from underneath

Real homes. Real results

See how we’ve helped homeowners fix their sinking floors.

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.

Watch Video

Learn more about Buildfix and how we re-level sinking indoor floors — from underneath.

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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.

Floor Slabs Sinking Inside Your Home?

Floor Slabs Sinking Inside Your Home?

Don't take our word for it

Pouring Cement On Top of a Sinking Slab Doesn't Fix What's Underneath.