Many laypeople look at having a soil test done as an inconvenience that cannot be avoided. Such people may not be aware of how the different soil conditions can affect the strength and durability of their homes. This article discusses some subsoil conditions, and how those soil conditions can affect your home if the builder does not take countermeasures.
Clay soil may expand or contract dramatically, depending on its moisture content. For instance, it can contract and crack when it dries up. It can also absorb moisture and expand. Imagine what those variations can do to your home’s foundation if nothing is done to stabilise that soil; the foundation may be torn apart when the clay soil underneath it contracts after a prolonged dry spell. Soil testing alerts the builder to this risk; he or she can mix that clay soil with more stable soil so that expansion/contraction cycles are minimised.
High Amounts of Organic Matter
Many homes are constructed on lots that used to be streams or rivers. Those depressions (valleys, streams or riverbeds) were reclaimed by filling them with soil taken from other locations. Imagine that tree stumps, plenty of grass and other organic materials were in that fill material; the contractor may have compacted that fill material, and it may have looked firm at the time it was compacted. However, as time elapsed, the organic matter (such as tree stumps) may have started decomposing. That compacted soil can settle as the organic matter within it decomposes (and reduces in volume). That can cause sections of your home to settle (sink). This is particularly true for those parts of your home that are directly above the decomposing organic matter. Soil testing is important because it can detect such risky soil conditions, and enable the builder to take precautionary steps (such as setting up steel piers to support the foundation).
A particular lot may have been a dumpsite (landfill) a long time ago. That dumpsite may have been abandoned, and it is now available for construction. However, someone may have accidentally dumped hazardous materials (such as soil contaminated with asbestos). The authorities may not have detected that hazardous material. You may risk being exposed to asbestos if soil testing is not done to rule out the presence of any hazardous substances at the construction site.
As you can see, any time and money that goes towards soil testing is money and time well spent. Do not undertake soil testing as a formality; look at that activity as a very important way to ensure that your home, and your family will be safe from any risks that could have been prevented if the problems had been detected before construction started.