Teretek® | Subsidence of staircase


Residential | Camden South, NSW | 2020

A single storey, double brick home in Camden South, New South Wales, had a large crack at the bottom half of an outdoor staircase. The homeowner wanted to fix the crack due to concern it would impact her ability to sell the property in the future.

The 20-25mm wide crack was caused by subsidence beneath the home’s concrete footings, which sat on clay soil and had sunk due to excess water pooling to the side of the stairs. The property’s owner had tried to repair the crack in recent years by replacing the bricks, however the crack eventually reappeared.

As the subsidence was quite severe, the owner sought a solution that would lift the stairs back into position and reduce the crack, while also re-support the staircase so the issue did not recur in the future.


Mainmark needed to deliver a solution that would improve the ground beneath the stairs, re-support the concrete footings, and lift the stairs back into alignment and reduce the gap in the brickwork as much as possible.


Mainmark’s Teretek® resin injection technology was identified as the most appropriate solution to Teretek® Re-Levels External Brick Staircase and Remediates Cracks remediate the stairs. Teretek is a two-in-one solution that delivers both ground improvement and relevelling. Likened to keyhole surgery, the Teretek solution is injected directly into the ground through very small injection holes. It then immediately expands, compacting and strengthening the ground, creating a solid foundation.

An environmentally inert solution, Teretek is suitable for most soil types including clay. The injection process is fast and efficient, with little or no excavation required. The non-invasive application method is also clean and causes minimal disruption to a home’s occupants.

The small treatment area required only 4 injection tubes to deliver the desired result, successfully lifting the stairs by approximately 20mm, and closing the gap in the brickwork by 90 per cent. In addition, another injection was then applied under the landing to level the last step at the bottom of the stairs. By using Teretek, Mainmark was able to minimise further movement and improve the overall structural integrity of the stairs.


I’m very happy with the job that Mainmark has done. A bricklayer had attempted to fix the stairs a few times in the past, but the solution never held. The stairs are now sitting nice and tight so I’m hopeful they will stay this way permanently.

The homeowner commented