A home’s foundation is the material that supports everything above and inside it. But what about the support system to the foundation itself? The soil below and around your home is essentially the foundation of the foundation.
Each type of soil has different properties which can affect the way a home’s foundation is supported. Knowing what kinds of soils these are and which one your house sits atop may allow you to catch problems in your foundation even before they arise.
Clay soil:
It is an expansive soil, which means it expands when wet and shrinks when dry. When clay is moist, it’s easily moved, manipulated, and shifted. These changes cause a great deal of pressure on foundations and can cause them to move up and down, and eventually crack. For this reason, clay is usually not a great soil to construct a home on.
Peat soil:
This is a dark brown/black soil formed by decomposed organic material. Peat is usually found near wetlands and is especially porous. Like clay, peat shrinks and expands depending on weather conditions and has a low bearing capacity, making it a poor support material.
Sandy soil:
When compacted with gravel and other materials, sand does not retain water and therefore will not cause any structures above it to shift. However, over time, sand particles can lose their friction and be washed away, creating gaps beneath a foundation. Helical piers are an effective fix for foundations supported by sand.
Rock:
Varieties such as bedrock, limestone, and sandstone have exceptionally high bearing capacities, which make them suitable for supporting buildings and homes. It’s imperative that a rock surface is level before a foundation is constructed, otherwise, the foundation must be held into place with anchors.
Loam:
This is an ideal surface for foundation. Typically, loam is a combination of sand, silt, and clay, and is crumbly/soft to the touch. Loam handles moisture in a balanced way and will generally not expand or shrink enough to cause damage.
If you’re planning to build your home, it’s best to figure out what kind of soil you’ll be working with and understand its properties. Even if you’re not planning anything, knowing about the soil type your home is built on may help to explain current or future foundation problems. Moreover, research is essential in order to learn.