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Void Filling & Soil Stabilisation NSW

Hollow-sounding slabs, dropping edges and gaps under concrete usually mean the ground beneath has washed away. Our void filling service injects polyurethane resin into the gaps left by erosion under concrete and water washout, then stabilises the soil so the slab is fully supported again.

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What Is a Void Under Concrete?

A void is an empty space between the underside of a slab and the ground underneath. Concrete is strong but relies on the soil beneath for support. When that soil is washed away or settles, the slab is left bridging a gap, and it will eventually crack, sink or rock.

Erosion Under Concrete and Water Washout: The Common Causes

  • Leaking or disconnected downpipes discharging next to a slab

  • Broken stormwater or sewer pipes beneath the concrete

  • Leaking pools and pool surrounds

  • Heavy rain running under slab edges and joints

  • Sandy coastal soils, which wash out easily

  • Poorly compacted fill that settles over time

Signs You Have Voids Under Your Slab

  • The slab sounds hollow when you tap or walk on it

  • Edges or corners have dropped, or a gap shows along the edge

  • Water disappears under the slab after rain

  • The slab rocks or moves underfoot

  • New cracks are appearing

How Void Filling Works

We drill small holes through the slab and inject high-density polyurethane mixture. It flows into the voids, expands to fill them and hardens quickly, restoring full support under the slab. If the slab has also dropped, we lift it back towards level in the same visit (see Concrete Jacking).

Soil Stabilisation: Stopping Future Movement

As the polyurethane mixture expands, it compacts loose and weak soil around it, firming up the ground the slab sits on. That reduces future settlement and movement. Polyurethane resin injection is also water-resistant, so it won't wash away like the soil it replaced.

Void Filling FAQs

Yes. If the slab is still level, we can fill the voids and stabilise the ground without lifting it, decreasing the risk of bigger problems later.

No. Polyurethane resin injection is water-resistant and doesn't erode the way soil and sand do.

Void Filling Across NSW

Based in Milton, we fill voids and stabilise slabs across the Shoalhaven, Illawarra, Eurobodalla, Bega Valley, Southern Highlands, Sydney, Newcastle and Canberra. Coastal properties with sandy soils are especially prone to washout, so it pays to act early.

Get In Touch

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Address

Milton NSW

Phone

0419 747 416

Email

info@levelupnsw.com.au

ABN

49700784014

Operating Hours

Monday - 8:30am - 5:30pm
Tuesday - 8:30am - 5:30pm
Wednesday - 8:30am - 5:30pm
Thursday - 8:30am - 5:30pm
Friday - 8:30am - 5:30pm
Saturday - 9:00am - 4:00pm