Dishing the Dirt on Soil: the connection between soil and the stability of a home’s foundation
Clay soil is not an ideal choice for the construction of concrete foundations. It is comprised of extremely fine particles of alkaline rocks such as limestone. When wet, clay takes on significant amounts of water. It becomes pliable and expands. If it meets with the foundation, it can generate enough pressure to shift the concrete. Conversely, when dry it tends to shrink. These repeated shifts of expanding and contracting will eventually cause cracks, taking its toll on the foundation’s stability over time and
Peaty soil is usually dark brown or black. It is made up of decomposing organic matter and typically is more damp feeling. It is easily compressible because of how much water it can hold. Peat reacts with water much like clay does, meaning it expands and shrinks. Concrete foundations built on a peaty ground are susceptible to cracking and shifting.
While not ideal for construction, silty soil is very fertile and great for growing crops. Typically found near rivers, silt is smooth to the touch and holds water longer because of its make-up of fine particles. Because the silty soil drains slowly it runs the risk of pushing against a foundation and weakening it.
Sand & Gravel
Small particles of weathered rock is what makes up sandy soil. It has a gritty texture and is typically very dry. It doesn’t hold water but instead allows for water drainage away from one’s foundation. It is a more suitable dirt for construction than peat or clay because when compacted it can add more stability to the soil. While sand does not offer much in the way of threats for cracking a foundation, it does have some potential issues. For one, it washes away little by little and over time, eroding the stability of the earth below the concrete foundation. To avoid water erosion issues, other materials are added to the sand and gravel to create a mix that isn’t prone to easily washing away.
Bedrock is not really a type of soil; it’s a hard material that lies beneath the topsoil. Commonly limestone, sandstone, shale or hard chalk, it is ideal for home foundation as it does not change shape or size when it gets wet. Because it does not typically shirt of move, home constructed on such typically do not see cracks for foundation settling in the same way a home clay or peat might. Bedrock has the upside of being able to bear heavier weight and offers stability to the max so long as it is level.
Loamy soils are more like a hybrid. Typically, a mix of organic material, along with sand and clay. Loamy soils are adequate for building on – better than clay or silt but not as good as bedrock. While copious amounts of undecomposed vegetation can create stability issues with loamy soil, water typically does not affect its ability to serve as a firm base for the foundation. The soil mixology of loam is great for supporting foundations because of its evenly balanced properties. Since the clay isn’t dominating the mix, water swelling at the foundation site will not lead to an increased risk for cracking. And since the sand doesn’t dominate the soil mix either, the risk of erosion is greatly reduced.
Knowing this information about soil is useful when looking for land to build a home on or when house shopping (as some added information to consider as you look). However, you may feel this information comes a little too late for you if you already own your home. This may be especially the case if you are seeing cracks in your ceilings or walls, have doors sticking, or uneven pavement – if these things are present it would behoove you to contact a professional for a quote. Oklahoma Foundation Repair gives free quotes and has financing available, too. The problems will only get worst left unchecked, so don’t delay. If you find that you are on these types of soils and worry about future damage potential, we can also come out and do an assessment for preventative maintenance and suggest upgrades to help protect your homes foundation and overall value. If you live in or near the Greater Oklahoma City Metro Area, we’d love the opportunity to show you why we are the fastest growing foundation repair company in the town. Give us a call at (405) 441-1643.