Not all cracks are the same; the type, size and location of cracking is important to consider when identifying the cause of the issue, as well as the best steps to resolve the problem.
In the same way, measuring the success of a remediation project draws on a combination of tools.
Different types of wall cracks
The most common types of wall cracks that generally appear in buildings are:
- Interior cracks affecting plasterboard, gyprock or brickwork
- Exterior wall cracks in brickwork or cement rendering of external walls
If wall cracks suddenly appear in your home, they may be a symptom of a deeper, structural issue. An earlier article highlighted the types of wall cracks that homeowners should act on, with location, direction and extensiveness of the crack likely to indicate the seriousness of the underlying problem.
Smaller hairline cracks are fairly common in walls and not usually cause for concern. Larger cracks that start at windows, doorways or corners of buildings may suggest the property foundations have sunk, subsided or lost strength, causing all or part of the building to sink.
Pay attention to whether the crack is jagged, horizontal or vertical, zig-zagged, stepped in brickwork, or follows mortar lines. If the crack is 5mm or wider, or you notice a complete separation in the mortar or cement between bricks, professional advice is recommended. Depending on the the underlying cause, you may need a plumber to address leaking pipes, or deeper investigations by a geotechnical engineer or structural engineer to determine the reason for strucutural issues before speaking with ground engineering experts about remediation solutions.
The process of remediation
Once the underlying issue has been identified as subsidence or reduced bearing capacity, there are several solutions to consider. These include traditional methods like concrete underpinning, or non-invasive resin injection, which is comparatively much faster and usually more cost effective.
Teretek® resin injection is designed to be applied once the exact areas of subsidence and weakness beaneath the structure have been pinpointed. Using a process likened to keyhole surgery, the engineered product both increases ground bearing capacity and re-levels the building with a high degree of accuracy. While the objective is always to improve the ground and return the structure to as close to level as possible, whether wall cracks fully close or not will depend on the direction of the crack and the soil beneath your home.
Why tape is applied over cracks
In many case, homes can be re-levelled within a day using resin injection, and the application process is tightly-controlled with constant monitoring using laser levels to ensure accuracy.
Mainmark applies a special indicator tape on to significant wall cracks before re-levelling works commence. This visual indicator is one of many measurement techniques that technicians use to carefully monitor change throughout the controlled remediation process. To answer a common question, the tape does not close wall cracks, but plays an important part all the same. For the trained eye, it may be possible to spot visible movement of the tape even before incremental change is picked up using the highly accurate laser level. The tape can also show how the structure is moving in response to foundation ground remediation, including the direction and degree of lift. In some cases, technicians may adjust the location of injection points accordingly.
Although the tape can be left in place for the homeowner to continue to monitor changes in the weeks following treatment, it is not necessary to do so. Once re-levelling works are complete, above ground structural repairs can take place with the help of a professional builder to patch and repaint walls as needed. For the best long term results following remediation works, the Foundation Maintenance and Footing Performance guide from Australia’s CSIRO provides expert advice for homeowners to help ensure both the building and property are well managed, with ongoing moisture ingress kept under control.
For more information and advice contact Mainmark on 1800 623 312 in Australia, on 0800 873 835 in NZ, or visit www.mainmark.com.
By James O’Grady
James O’Grady is the Sales and Business Development Manager at Mainmark. He is a civil engineer with 25 years’ experience in structural engineering, construction materials and ground treatment.