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What the cracks in your walls are trying to tell you

by (not verified)
10 July 2018

Did you know that cracking walls and uneven floors in homes are usually symptoms of a deeper, structural problem? 

For homeowners, regardless of where they live, identifying structural issues early and addressing them in the right way is vital. Here’s a tip: understanding the soils beneath your home can be the key.

“Consulting an expert who knows how soils behave can help make sure that when you solve one issue you don’t cause another. Getting it wrong can have disastrous results,” says Mainmark ground engineering specialist James O’Grady.

Many structural issues are the result of unstable ground or subsidence, so understanding what’s happening in the ground will help to identify the cause and possible solutions.  

“One home I recently visited was substantially damaged after a trench was dug beneath the floor to fix a leaking pipe.  It was then back filled with sand,” says James.  

“The property was built on reactive clay soil. The sand-filled trench created a channel that funnelled ground water under the home, saturating the clay and ‘heaving’ the entire building.

“The fix caused far more extensive damage than the original problem, all because the soil type hadn’t been considered. Understanding soils is key to finding an effective, sustainable solution to structural issues so it’s important to get advice from both structural and geotechnical experts before deciding on the right remediation plan.”

The soil types commonly encountered in ground remediation work include reactive clay, sand and silt, fill and organic soils. Each has different characteristics:  

  • Reactive Clays

Structural problems often result from varying moisture levels in reactive clay soil. It swells when wet and shrinks when dry causing subsidence in drier conditions, or heave in wetter, areas. The soil can become oversaturated due to broken sewers and storm water pipes, burst mains or sometimes even poor overland drainage. Over-saturated clay also loses its bearing capacity causing building footings to settle in the weakened soil which can sink even further as it dries out.

  • Sand and Silt

Structures on sand and silt soils often experience settlement caused by ground water, a natural underground watercourse or a leaking sewer or storm water pipe. The finer grains are washed away leaving larger grains to settle, and the building’s footings and foundations become unsupported, compromising the structure above. 

  • Fill

Fill is earthen material placed and compacted in a hole or depression. It can consist of soil, and can also include aggregate, rock or crushed construction waste. Structures built on fill are susceptible to the same issues as those on sand and silt, especially when water flows wash away finer material. Settlement is worse if the fill is poorly compacted.  

  • Organic

Organic soils, especially peat, are weak and highly compressible which makes them prone to settlement as the weight of any structure causes compaction. Primary settlement decreases over time, but can total 100s of millimetres, resulting in significant structural issues. 

Mainmark’s Teretek resin injection solution can be used to re-level buildings and remediate ground issues to strengthen a building’s foundations.  Suitable for most soil types, it is applied at very precise injection points and expands in the ground, both compacting and strengthening the soil. Teretek is non-invasive, quick and cost-effective, as it can be applied in situ under existing structures, without the need for major excavation work, or manual compaction. 

For more information and specific advice about how to address these types of ground issues, contact Mainmark on 1800 623 312 or visit www.mainmark.com.

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