Most subsidence issues in the UK are created by unstable ground, often caused by extreme weather conditions such as hot, dry summers and heavy rainfall or flooding. Other factors such as leaking pipes, vegetation with invasive roots, loosely packed soils or old landfill sites, excavation work and inferior concrete foundations can also be sources of subsidence.
Common signs of subsidence around your home are:
- Cracks in walls larger than 5mm
- Sinking or sloping floors
- Doors and windows that won’t close
Minor cracks alone may not necessarily be a cause for concern, but larger cracks can be a sign of something more serious and should not be ignored. Cracks which are wider than 5mm, or zigzag/stepped cracks in brickwork which usually follow the mortar lines, are indicators of possible structural problems.
While the anticipated cost to arrest subsidence and rectify foundation damage may seem prohibitive, if the signs are ignored, costs will increase over time as the situation worsens and not addressing the issue could even devalue the property. The two most popular methods of resolving foundation subsidence issues are traditional concrete underpinning and modern resin injection. Both are proven methods, yet involve very different procedures.
Concrete underpinning: an expensive, labour intensive process
Historically, concrete underpinning has been the most common method for strengthening a building’s foundations and fixing subsidence. This tried and tested method has been used for more than 100 years. However, it is a costly and time intensive process that can take weeks or months to complete. It’s also inconvenient for homeowners, who are generally required to vacate their home while the work is being completed.
The basic premise of concrete underpinning is to increase the depth of the structure’s foundation to extend it to stronger soil. To achieve this, large holes are dug beneath the structure and concrete is poured into the spaces in accordance with the project specific plan. This process essentially creates new foundations underneath the original, to further stabilise the structure. Depending on the extent of the issue, homeowners will also need to consult with engineers and gain appropriate council permits before commencing the underpinning work which can add weeks to the project. Once work begins, cement trucks and other heavy vehicles will need to transport concrete, tools and machinery onto the site, adding further disruption. Homeowners may also find that existing plants and landscaping around the home’s perimeter are damaged.
Resin injection: a faster, smarter, less-invasive solution
A more modern method is resin injection. Used globally for over 20 years, this non-invasive solution is able to remediate homes affected by subsidence in significantly less time than traditional concrete underpinning.
This process involves injecting resin into the existing foundations through small incisions made in the ground, typically only 16mm in diameter from outside a home. The resin then flows into the soil and expands, compressing the surrounding soils while filling voids and cracks.
Mainmark’s proprietary Teretek® engineered resin injection solution is a proven, cost-effective and quick alternative compared to the invasive traditional underpinning methods. Using a process similar to keyhole surgery, the work can often be completed in one day. It is widely used to strengthen foundation ground, and to raise, re-level and re-support buildings in residential, commercial, industrial, mining and infrastructure projects.
Resin injection strengthens and improves the ground beneath a structure. By using Mainmark’s Teretek resin injection solution, homeowners will usually see immediate results:
- Windows and doors will begin to work properly again
- Gaps between skirting boards and sunken floors will realign
- Cracks in walls will begin to close up
For more information regarding resin injection, please visit mainmark.com/uk/technology/teretek/
By Victor Chirilas
Victor is the Operations Manager at Mainmark UK, with over 10 years’ experience in project management and construction management. Having joined Mainmark in 2009, he has managed projects in Australia, the UK and New Zealand including the remediation of the Christchurch Art Gallery which was shaken by the 2010 and 2011 earthquakes that hit New Zealand’s South Island, the old Bank of New Zealand building in Kaiapoi and Ultima Furniture’s warehouse in the UK.