Concrete Slab Lifting & Sunken Concrete Repair Experts

House slab lifting is a ground engineering process used to raise, re-level and re-support concrete that has sunk or become uneven.

An engineered material is injected beneath the affected slab to fill hidden voids, improve support and carefully lift the concrete towards the required level. This can often preserve the existing concrete without excavation or complete slab replacement.

Your concrete slab may need lifting if you notice:

• Uneven or sloping concrete
• A noticeable step between adjoining slabs
• Sinking internal floors
• Gaps beneath slab edges
• Cracks caused by uneven settlement
• Water pooling in areas that previously drained
• Doors that scrape against an uneven floor
• Trip hazards on paths, driveways or patios
• Hollow areas beneath the concrete
• Concrete pulling away from the house, garage or surrounding structures

These symptoms can indicate slab settlement, voiding or a loss of support beneath the concrete.

Concrete slabs generally sink when the ground beneath them settles, erodes or loses its ability to provide consistent support.

Common causes include poorly compacted fill, leaking pipes, stormwater problems, soil erosion, changing soil moisture, tree roots, weak foundation soils and voids beneath the slab. Australian building guidance identifies changing soil moisture, settlement, erosion and tree roots as common causes of foundation movement. Can slab lifting fix uneven or unlevel concrete?

Yes. Slab lifting can be used to correct uneven or unlevel concrete when the slab remains structurally suitable and the underlying ground can be treated.

The process can restore a more consistent level, remove stepped edges, reduce trip hazards and improve drainage falls. The amount of correction possible depends on the slab’s condition, surrounding structures and cause of settlement.

Residential slab lifting may be suitable for:

• Internal concrete floors
• Garage and carport slabs
• Driveways
• Footpaths and walkways
• Patios and outdoor entertaining areas
• Pool surrounds
• Concrete steps and landings
• Garden paths
• Shed slabs
• Concrete areas beside the house

The slab must be assessed to determine whether lifting, re-support or replacement is the most appropriate option. Mainmark identifies internal floors, garages, driveways, paths, patios and pool surrounds as common slab-lifting applications. How does resin injection slab lifting work?

Small injection points are created through or beside the affected slab. Mainmark’s engineered Teretek® resin is then injected beneath the concrete at controlled locations.

As the resin expands, it fills voids, improves contact with the underside of the slab and helps strengthen or compact weak surrounding ground. Continued controlled injection can then gently lift the slab towards the required level. Can an internal house floor slab be lifted?

Yes. Resin injection slab lifting can be used for some sinking or uneven internal concrete floors.

The injection points are generally small, allowing the slab to be treated without removing the entire floor. Floor coverings, cabinetry, internal walls, plumbing and surrounding finishes must be considered before any lift is attempted.

Where the movement involves the home’s structural foundations rather than the floor slab alone, a broader foundation repair or house re-levelling solution may be required.

Sections of a house slab can sometimes be lifted and re-supported using controlled resin injection. However, the suitability of the treatment depends on the foundation design, structural condition and reason the house has moved.

If the footings or main foundations have also settled, the property may require ground improvement, foundation re-support, resin injection underpinning or a broader house re-levelling plan rather than slab lifting alone.

These terms are often used interchangeably, but they generally describe related parts of the same process.

Slab lifting describes raising a sunken concrete slab.

Slab jacking describes injecting material beneath the concrete to lift it.

Concrete levelling describes the intended result of correcting the uneven surface.

The materials and techniques used can vary considerably between traditional cement-based mudjacking and modern resin injection slab lifting.

Traditional mudjacking generally pumps a cement, sand and water mixture beneath the concrete. Resin injection uses a lightweight engineered polyurethane material that expands after it is injected.

Mainmark uses Teretek® resin injection to fill voids, improve ground support and lift the slab in a controlled manner. The appropriate technique depends on the slab, site access, ground conditions and treatment objectives. Is slab lifting the same as underpinning?

No. Slab lifting and underpinning address different structural problems.

Slab lifting raises and re-supports a concrete floor, driveway, path or similar slab. Underpinning restores support beneath the structural foundations or footings of a house.

If both the concrete slab and the foundations have moved, the project may require a combination of ground improvement, foundation repair, void filling and re-levelling.

Void filling restores support by filling a gap beneath the concrete. It does not necessarily raise the slab.

Slab lifting combines re-support with controlled level correction. Resin is injected beneath the affected concrete to fill the void before further controlled expansion is used to lift the slab.

Some properties require void filling only, while others require both void filling and slab re-levelling.

A cracked slab may still be suitable for lifting if the concrete remains structurally sound and the individual sections can be raised safely.

Slabs with extensive deterioration, severe fragmentation, reinforcing corrosion or major structural damage may be better suited to replacement. The slab should be assessed before deciding whether lifting is practical.

Slab lifting addresses the loss of support and uneven settlement beneath the concrete. It does not directly repair the crack itself.

Some cracks may narrow as the slab is raised, but remaining cracks and damaged joints may require separate concrete repairs or sealing after the lifting work is complete.

Slab lifting may be preferable when the existing concrete remains in reasonable condition and the main problem is settlement or voiding beneath it.

It can avoid demolition, concrete removal, disposal and reconstruction. Replacement may be more appropriate when the slab is severely cracked, deteriorated, incorrectly designed or no longer structurally suitable.

A site assessment will determine whether the existing slab can be safely retained and re-supported.

The cost of house slab lifting depends on:

• The size of the affected concrete area
• The amount the slab has sunk
• The volume of voiding beneath it
• The depth and condition of the supporting ground
• Site access
• The number of injection locations required
• The slab’s structural condition
• Whether ground improvement is also needed
• The required amount of level correction

Because these factors vary between properties, a site assessment is needed before an accurate slab-lifting quote can be provided. Mainmark similarly identifies slab size, settlement extent, accessibility and the cause of movement as key cost factors. How long does residential slab lifting take?

Many targeted resin injection slab-lifting projects can be completed within several hours, although larger or more complex areas may take longer.

The timeframe depends on the size of the slab, amount of settlement, ground conditions, access and level of correction required. Mainmark states that some Teretek® slab-lifting work can be completed within hours rather than days. Can I use the concrete immediately after slab lifting?

Concrete treated with Mainmark’s Teretek® resin injection can generally be returned to use soon after the work has been completed because the material cures rapidly.

Mainmark states that treated areas can be reopened to traffic and full use once the repair is complete. Property-specific instructions should still be followed before driving or placing heavy loads on the treated slab. Do I need to move out while an internal floor is being lifted?

Homeowners can often remain in the property during targeted resin injection work because the process normally requires small injection points rather than extensive demolition or excavation.

Temporary access restrictions may apply to the room or treatment area. Mainmark will explain any requirements relating to furniture, floor coverings, services and property access before work begins.

Resin injection is intended to provide long-term re-support beneath the treated slab. However, the result also depends on whether the underlying cause of settlement has been properly addressed.

Continuing pipe leaks, drainage problems, erosion or major soil-moisture changes can affect the ground in untreated areas. Mainmark describes its resin as durable and water-resistant, but each property still requires a site-specific assessment. Can the concrete sink again after slab lifting?

A treated slab is intended to remain supported, but future movement may occur if an unresolved problem continues to affect the ground.

Before lifting the slab, contributing issues such as leaking pipes, damaged stormwater lines, poor drainage or ongoing soil washout should be identified. Other untreated areas around the property may also move independently over time.

Yes. Any active leak or drainage problem contributing to soil erosion, softening or settlement should generally be addressed as part of the repair plan.

Lifting the slab without correcting an ongoing water problem may allow the underlying ground conditions to deteriorate again. Australian homeowner guidance recommends repairing leaking services and directing surface water away from house foundations. Do I need a structural engineer before arranging slab lifting?

You do not necessarily need to organise an engineer before requesting an initial slab assessment.

However, engineering advice may be recommended where the slab forms part of the home’s structural foundation, the movement is extensive, wall cracking is significant or the cause cannot be clearly identified. Australian building guidance recommends further investigation by a civil or structural engineer where substantial foundation movement or significant cracking is present.