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Video | How we repair sunken concrete

Need a sunken concrete slab solution? Booking a FREE structural assessment today

Need a sunken concrete slab solution? Booking a FREE structural assessment today

What does
sinking concrete
look like and what
does it indicate?

Sinking concrete slabs in your pool area, garden landscape, patio, stairways and driveway are easy to identify. These concrete slabs will usually appear to have depressed or tilted at uneven angles in the ground, posing a tripping hazard.

Sinking concrete slabs in internal environments such as your home, garage or workspace are harder to see as they’re not so obvious.

Sinking concrete of this nature indicates there are issues within your building’s structure due to shifting ground. It also indicates there may be an immense amount of pressure being placed on your home from the ground up.

Read on to learn how to identify sinking concrete within your home and what causes it.

What are the tell-tale signs of internally sinking concrete?


The Floor Drops

If one side of your concrete floor has sunk deeper than the other, it may cause the floor to slant. This can create an unwanted step and form a dangerous trip hazard. When you and your family walk across the floor, you may feel like you’re walking up or down steps.


The Floor Bows

If the central area of your concrete floor is sinking downwards, your floor will bow. A bowing floor will subtly dip in a concave shape. The outer area of the floor will be a touch higher than that of the central area and if you were to place a ball down, it would roll towards the centre of the room. After sometime, internal doors will begin to jam as the forces of the structure alter.

Sunken concrete in a home

Gaps under Skirting Boards

Skirting boards are meant to sit flush against the base of your interior walls. If they’re pulling away to reveal gaps underneath the internal walls of your home, a sunken concrete floor may be the cause. The skirting has moved, but the walls have not.

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What are the leading causes of sinking concrete?

Flooded aprtment complex

Stormwater Damage

Flooded or overflowing stormwater drains can be one of the biggest reasons for sinking concrete. Instead of directing water away from your home, they direct water towards and around its foundations.

With nowhere for the water to run off, the water can only soak into the ground underneath your concrete floor, driveway, stairways, patios or pool area. This excessive soaking causes soil erosion leading to instability of the ground and eventually sinking.

Clogged gutters

Poor Drainage

This is a similar cause to stormwater damage in that there’s an overflow of water. But instead of the water coming from overflowing or flooded stormwater drains, it comes from your home’s burst, cracked and/or unconnected pipes.

The malfunctioning pipes leak and pool water into specific spots underneath your concrete slabs and floors. This causes the soil to become saturated, weak and unstable leading straight to sinking concrete.

Poor Compaction of Sub-Soils

Poor Compaction of Sub-Soils

Builders have a responsibility to compact soils before constructing a home upon it. Compacting soils drives air out from between the soil grains, densifying the ground to make it more stable to build on. Sometimes, builders deliberately skip the soil compaction process to save time, only complete a fraction of the process or forget it entirely.

In any case, soil that isn’t compacted properly is still full of air. Heavy concrete placed on top of a surface like this is bound to sink.

Excavator vibrations


Concrete can sink due to intense vibrations in the ground. Excavators operating at a nearby construction site, semi-trailers passing by at high speed on a local freeway and planes taking off and landing at a nearby airport can all bring on these intense vibrations. These vibrations tend to shake and aerate soil which eventually leads to instability and sinking concrete.

Reactive Clay

Reactive Clay

Reactive clay soil is a dense material that expands under wet conditions and contracts under dry, hot conditions. If your concrete slabs or floors are built upon reactive clay, they’re susceptible to lifting and sinking throughout the year. If your concrete happens to be sinking while the weather is extremely hot and dry, it’s likely your concrete is sitting on reactive clay soil.



Landslip is more often than not a natural event, caused by a build up of subterranean

water near a slop or embankment. As the ground shifts during a landslip event, any structure above, including concrete slabs, can be left dangerously exposed.

Need to stop the sinking concrete right now?

Sinking concrete can effect the stability of your home’s structure. If you want to stop your concrete from sinking further, feel free to get in touch.

We’re ready to help, starting with a FREE assessment and quote.

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