What does weak ground mean?

Weak ground occurs when the layers of earth are unstable and/or loose.

Weak ground cannot adequately support the weight of structures or floors, so they subside and cause hazards. Uneven concrete floors, fractured floor tiles, and wall cracks, are all strong indicators of weak ground beneath the structure. Weak ground needs to be fixed as quickly as possible to prevent further damage.

Jet grouting

Jet grouting used to strengthen ground on a massive scale.

Teretek deep-lift solution

Teretek deep-lift solution helping to stabilise weak ground

What causes weak ground?

There are a number of different things that can cause weak ground, both natural and man-made. For example, the ground may already be made up of loosely-packed materials such as soil or sand. Or human activities such as drilling and excavating can loosen previously-dense ground.

Weak ground can happen over a large area or in smaller areas. Ground that is not uniformly weak will still lead to subsidence issues.

Different types of ground are susceptible to different conditions. For example, clay is prone to contracting in drought conditions, gravel can be affected by nearby construction or heavy traffic, and dirt can be softened by excess water.

Regardless of the cause, weak ground is reason to be concerned. Subsidence is the most common issue, which needs to be fixed to protect the building and its inhabitants.

Likely causes:

Water flooding the ground

Drought drying out soil

Washaways from broken pipes (such as water, sewer, stormwater drainage)

Poorly-compacted fill

Liquid, gas, or mineral resources being removed from the ground


Earthquake and seismic activity, often resulting in liquefaction

Tree roots can suck moisture from the ground

Vibrations caused by heavy road traffic or by machinery

Absence of an organised footing system in very old buildings or in buildings with additions or alterations

Nearby excavation

Heavy loading

Deterioration of retaining walls

How to fix weak ground?

Mainmark specialises in soil stabilisation and ground compaction, foundation repairing, strengthening weak ground and making it suitable to support existing structures like buildings, bridges, and roads.

Mainmark’s proprietary Teretek engineered resin solution assures sub-grade stability under existing on-ground structures including buildings, concrete floors, driveways, roads, paved airport runways, bridge approach slabs, bridge abutments, and more.

Mainmark’s methods are fast, precise, neat and tidy, and don’t generally require you to vacate the building while work is being done.

Various product warranties and Building Code requirements apply (please contact us to see which apply in your region or country).

Weak ground under homes

Mainmark’s ground-strengthening techniques create a strong foundation under on-ground structures of any size, from driveways to airport runways, and from residential homes to large office buildings. We have successfully strengthened and re-levelled the ground under thousands of homes around the world.

We visit your home, assess the damage, and discover the cause. Our experienced engineers and technicians establish the approach needed, creating a plan specific to the needs of your house.

As the weak ground under houses is strengthened, the house and its sunken floors and driveways are re-levelled; any internal and external wall cracks generally close up too. Most importantly, structural damage is resolved and, with a stable foundation, the future of the house is sound.

Our foundation repair solutions are the modern alternative to the traditional way of underpinning; it’s like keyhole surgery compared to concrete underpinning. Our proprietary solutions are cutting edge and use a series of small resin injection holes to underpin concrete slab floors. We can also raise and re-level ‘waffle-pod’ slabs, strip footings, and raft slabs, plus we can infill under paths and driveways.

The method Mainmark most often uses involves injecting structural, expanding resins into the ground. This resin injection method is most effective where the sub-grade soils are cohesive. The resins and hardeners mix together in the ground, and expand to compact the adjacent soils and increase their load-bearing capacity.

Benefits of Mainmark’s ground stabilisation methods:

Can be carried out at one or more depths, as deep as 14 metres under the surface

Can increase the bearing capacity of weak strata under structures by up to 500 per cent

Can be carried out in conjunction with raising and re-levelling the on-ground structure

Can be used to prepare structures that need to support increased loads, e.g. when there is to be an addition to the building itself

We don’t make a mess: there is no concrete dust, water, or any other materials to clean up

There is minimal disruption to your daily life

We don’t cause further damage to the house, driveways, or landscaping

With simple jobs, residents can stay in the home and may not even need to move furniture

Techniques are non-invasive: we don’t tear up floors or excavate ground

Our methods are fast, completed in a fraction of the time of traditional methods; we can often finish your project in as little as one day

The products and techniques we use have zero negative impact on the environment.

Mainmark ground strengthening correction methods used on homes

For expert advice on identifying the causes of movement in a building, download a copy of ‘Foundation Maintenance and Footing Performance: A Homeowner’s Guide’ from CSIRO.