Residential Ground Improvement

Residential ground improvement is a ground engineering process used to strengthen, modify or replace weak and unstable soil beneath a home. It can improve the ground’s load-bearing capacity, fill voids and restore more consistent support beneath foundations, footings and concrete slabs.

Depending on the property and ground conditions, Mainmark may use solutions such as Teretek® resin injection or Terefil® lightweight cellular concrete.

Signs that your home may have weak or unstable ground beneath it include:

• Cracks that continue to widen or reappear
• Cracked brickwork
• Sinking or uneven floors
• Sloping concrete slabs
• Doors or windows that stick
• Gaps around door and window frames
• Sections of the house settling at different rates

These symptoms can indicate foundation movement, settlement or subsidence, but a site assessment is needed to determine the underlying cause.

Weak foundation soils and residential ground movement can be caused by poorly compacted fill, natural soil settlement, erosion, changing moisture levels, leaking pipes, blocked downpipes, poor drainage, tree roots or voids beneath the foundations.

Reactive clay soils are particularly affected by changing moisture conditions because they can shrink during dry periods and expand when wet.

Ground improvement can help re-support a sinking house when the movement is being caused by weak, loose, compressible or voided ground. The treatment strengthens or improves the supporting soil beneath the affected foundations, helping reduce the risk of further settlement.

Any contributing issues, such as leaking plumbing, poor stormwater drainage or changing soil moisture, may also need to be addressed as part of the overall foundation repair strategy.

Ground improvement, underpinning and slab jacking are related but different services.

Ground improvement treats the soil supporting the home. Underpinning strengthens or re-supports the building’s foundations. Slab lifting or slab jacking focuses on raising sunken concrete.

Resin injection can sometimes provide ground improvement, foundation re-support and level correction in one targeted process, depending on the property and site conditions.

Small injection points are created around the affected foundation or slab. An engineered expanding resin is then injected into the ground at controlled locations and depths.

As the resin expands, it can fill voids, improve ground-bearing capacity and restore support beneath the structure. Where conditions allow, the injection process can also be carefully controlled to assist with foundation or floor re-levelling.

Ground improvement can sometimes be combined with foundation re-levelling. Once the weak ground has been strengthened and voids have been filled, controlled resin injection may be used to raise settled sections of the home towards the required level.

The amount of lift that can safely be achieved depends on the foundation design, soil conditions, extent of movement and condition of the building. Results therefore vary between properties.

Yes. Targeted resin injection can be used to fill voids and restore contact between the ground and a residential footing, foundation or concrete slab.

Larger, deeper or more complex voids may require a different ground engineering material or treatment method. Mainmark assesses the size of the void, surrounding soil and structural requirements before recommending a solution.

No single foundation repair method is suitable for every property. The most appropriate solution depends on the soil type, foundation construction, depth of weak ground, cause of the movement, extent of settlement, site access and required level correction.

Some homes may be suited to resin injection ground improvement, while others may require traditional underpinning, structural foundation repair, drainage work or another engineered solution.

The cost of ground improvement depends on the size of the affected area, depth of treatment, ground conditions, foundation type, amount of movement, accessibility and whether foundation re-levelling or void filling is also required.

A site assessment allows Mainmark to identify the likely cause of the problem, determine an appropriate treatment plan and provide a detailed quote for the property.

Treatment time depends on the size and complexity of the project. Targeted resin injection is generally faster and less disruptive than traditional excavation-based underpinning because it is applied through small injection points and does not usually require large areas of the property to be excavated.

Some residential projects can be completed in as little as a day, while larger or more complex foundation repairs may take longer.

It is generally best to investigate and address the cause of foundation movement before completing cosmetic crack repairs. Repairing the plaster or brickwork alone will not resolve weak ground, foundation settlement or a loss of support beneath the home.

Once the foundation has been re-supported or re-levelled and the movement has been addressed, any remaining cracks can be repaired separately.

You do not necessarily need to organise an engineer before requesting an initial site assessment. However, an engineer may be recommended when the movement is significant, the structural damage is complex, the cause is uncertain or formal engineering documentation is required.

Australian building guidance recommends further investigation by a qualified civil or structural engineer where substantial foundation movement or significant cracking is present.