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Underpinning Solutions

Common causes of a shifting house foundation

Sinking and cracked floors, a crack in the wall or concrete slab, and doors and windows that won’t close properly can all be warning signs of ground weakness under a structure. If a building becomes un-level due to subsidence, it can result in significant and expensive damage, particularly if left unaddressed. This is when homeowners may look for solutions that can effectively ‘underpin’ their home, a process sometimes referred to as house restumping or reblocking.

Mainmark’s approach to foundation repair uses unique underpinning techniques that are like keyhole surgery. Having previously used Uretek®, we now utilise our proprietary Teretek® engineered resin solution as it is a fast and reliable alternative to concrete underpinning.  It addresses subsidence by re-levelling concrete slab floors, strip footings, raft slabs, infill slabs, and driveways


First, our Teretek resin is injected into the ground beneath your home through tiny holes (typically 16mm in diameter, but as little as 6mm).

Then, the Teretek resins expand, filling any voids and compacting any soft ground, to underpin the footings and re-level the home.

Meanwhile, the enormous compacting pressure is controlled by constant laser monitoring for optimum results:

  • Wall cracks usually close up. Then, only some re-pointing of mortar joints may be required for brickwork, and some fine patching and repainting may be needed for plaster or render walls.
  • Windows and doors usually work properly again.
  • Gaps between skirting boards and sunken floors also usually close up.


The materials we inject below concrete have been specifically engineered to resist shrinkage or deterioration causing significant settlement. As such, the Teretek engineered resin is warranted by Mainmark for 50-years, in strict accordance with the product durability requirements of the applicable local, state or national Building Code.

Underpinning Methods


When it comes to foundation repair, underpinning has been the method of choice for many years. Compared with traditional concrete underpinning, Mainmark’s underpinning method is fast, clean, reliable, cost-effective, and non-intrusive.

Our Teretek resin injection solution achieves re-levelling faster and more reliably than concrete underpinning. On average, we can raise your home back to level as little as a day or within one or two weeks depending on the technologies we use, compared to the many weeks usually required for concrete underpinning. Also, with resin injection, there is no mess: it doesn’t require excavation, water, cement, or concrete.

Importantly, you usually don’t need to vacate the premises. Unlike concrete underpinning, which requires extensive internal work, our Teretek resin injection solution often doesn’t require internal work. However when it is required, the minuscule holes (as little as 6mm in diameter) can be drilled between tiles and even through carpet, and furniture doesn’t usually need to be moved.

Our foundation repair method is ideal even in clay, as the resin injection addresses underlying subsidence problems. It delivers re-levelling, improved bearing capacity, and maintaining a uniformity of bearing strata.

Concrete underpinning should be avoided to address subsidence in poor ground conditions such as non-cohesive, sandy, or muddy soil, or poorly-compacted fill. The reason being that the added weight of concrete can make the situation worse. Instead, the Mainmark underpinning method delivers the correct specific rigidity to avoid further damage.

Underpinning Costs

As well as being more convenient, safer, and more reliable, our Teretek engineered resin injection solution is usually more cost effective than traditional concrete underpinning.

However, the actual cost of underpinning will depend on many factors, including:

  • your location
  • the actual cause of the problem
  • the nature and condition of the foundation soil
  • the type and profile of the building footings
  • the surroundings e.g. access to the site, adjacent buildings or retaining walls
  • unknown or unforeseeable underground conditions
  • the volume of material that will be required
  • the time that the work will take.

If only one small corner of the house needs re-levelling, then concrete underpinning may be cheaper, but it may also give rise to additional challenges. For example, new cracks can develop in the house if only one part of the foundation is concrete underpinned.

In most cases, the cost of the resin injection will be lower than other methods, particularly concrete underpinning.


Mainmark offers comprehensive Teretek resin injection foundation repair services across Australia and New Zealand, including:

Perth: The soil in Perth varies. Mainmark has been underpinning Perth homes for many years, overcoming subsidence issues.

Adelaide: Mainmark has been underpinning Adelaide buildings for many years. In South Australia, underpinning is critical since many of Adelaide’s buildings sit on concrete slabs, or concrete strip footings.

Melbourne: We provide reliable foundation repair and house underpinning across Melbourne, addressing issues caused by prolonged drought.

Mildura and regional Victoria: Many Victorian houses are built on concrete. Mildura is no exception, making it a key location for Mainmark’s underpinning method.

Hobart and Launceston: Tasmanian homes have been known to suffer from subsidence and can be addressed quickly and reliably by Mainmark’s underpinning method.

Sydney: It is common for homes in the Sydney area to require underpinning due to a mixture of high drought and heavy rain fall seasons causing ground subsidence. Mainmark has successfully raised and re-levelled hundreds of Sydney homes and driveways.

Newcastle and Cardiff: Drought and excessive rain, as well as Newcastle’s famous earthquake have contributed to a need for house raising. Mainmark offers reliable house re-levelling and raising in Newcastle and Cardiff.

Brisbane, the Gold Coast, and the Sunshine Coast: Mainmark has been underpinning Brisbane and south-east Queensland homes for decades. Underpinning Gold Coast and Sunshine Coast homes is critical due to the sandy soils.

Mackay, Townsville, Cairns and Far North Queensland: When it comes to house raising, Townsville and other regions of FNQ require significant underpinning due to extended periods of rain and drought.

Auckland and Wellington: We’ve been underpinning Auckland homes for many years and have extensive experience across the North Island.

Christchurch and Kaikoura: Mainmark have helped thousands of Christchurch homes and buildings, affected by the earthquakes, with level correction and ground strengthening.