Teretek® | Subsidence

Wall crack before/after Teretek® resin injection


Single storey home | Woombah, Northern NSW, Australia

The owner of a residential property in Woombah, NSW, contacted Mainmark after noticing multiple cracks around the home and was concerned that one corner of the house was subsiding.

The single storey, brick veneer house is built on clay subsoil. This type of soil typically causes the ground to expand and contract as moisture levels change. Upon inspection, Mainmark found the home had subsided 30mm in one corner where a blocked storm water downpipe was located. When it rained, the blockage would cause isolated flooding, weakening the surrounding ground, causing the corner of the home to subside.

The subsidence had caused multiple cracks to appear in the home’s external brick work and large walls cracks were evident through the internal plasterboard around the windows. There was also a noticeable fall in the floor, which had dropped due to the subsidence.

The property’s owner wanted to address the subsidence however was worried about damaging the immaculate gardens and the surrounding concrete path. Conventional underpinning would have required excavation with the use of heavy equipment, resulting in the need to remove and replace the footpath surrounds.

The client was seeking a less invasive remediation option. Mainmark used its proprietary Teretek resin injection solution to deliver a non-invasive and cost-effective alternative.


The homeowner required Mainmark to achieve ground consolidation to the corner of the home that had subsided, and then raise and re-level the sunken area. The work also needed to be undertaken without damaging the property’s surrounding gardens or footpaths.


Mainmark used its Teretek resin injection solution to improve the ground bearing capacity of the soil beneath the corner area of the home. Teretek is a unique two-in-one solution that is applied in a process likened to keyhole surgery that strengthens the soil and re-supports existing structures.
Teretek is injected directly into the ground via small tubes. On entry, the components mix by chemical reaction to consolidate weak and unstable soil. The application process is quick and easy, and as it does not require any excavation work, causes minimal disruption to property occupants.
The Woombah home had subsided 30mm at the affected corner and was successfully re-levelled via 15 injection points which were inserted at multiple depths along the external perimeter footing. The work was completed in a single day without causing any damage to the surrounding gardens or footpaths.

The homeowner was very happy with the outcome,

Mainmark provided an excellent solution to re-support my home. It was an amazing experience watching the large cracks disappear as the home was lifted back to level and I was impressed that the work was able to be completed without causing any mess or damage to my home or garden. I now have peace of mind that the problem has been resolved.