Do Soil Types Affect Foundation Strength? Detailed Explanation

Jul 22, 2022 | Blog | 0 comments

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Yes, soil types affect the foundation strength of a house. Many people overlook the importance of soil type despite its importance to the foundation. As a result, such buildings come with high maintenance costs due to frequent foundation repairs. You need to familiarize yourself with the different types of soils and how they affect a house’s foundation. In addition, you also need to know the signs of foundation damage and call for repairs to avoid further damage. Read this article to get a detailed explanation. 

Type of Soils and How They Affect Foundation

Different soil types have specific properties that affect a house’s foundation. Here are the common types of soil.  

  • Peat

Peat is black or dark brown soil in wetlands and comprises decaying organic matter or vegetation. This soil type is highly compressible, weak, and has high water content. It is considered poor for foundation because of low bearing capacity and shifting around. Peat changes its structure when dry, leading to serious shrinkage and foundation distress. 

  • Silt

Silt is made of small particles and rocks, making it smooth and fine. This soil retains water for a long time hence its cold temperature and poor drainage. Silt soil is unsuitable as it expands, pushing the foundation and weakening it. The high water retention also makes it prone to mold growth. In addition, the water can find its way through the concrete slabs and erode it after a while. 

  • Clay

Clay is fine-grained soil material that contains a molecular film of water. This soil basically the expansive clay soil; hence develops plasticity when wet but hardens when dry. When wet, clay soils expand and pressures the foundation’s walls. Drying, on the other hand, shrinks the soil, causing it to shift and causing fissures. However, digging to a depth with stable moisture can avert this foundation problem from expansive soils. 

  • Loam

Loam is arguably the best for a foundation because it contains sand, expansive clay soils, and silt. This type of soil absorbs moisture well and dries out evenly, as its components enable easy drainage. However, it will be best to filter out undecomposed material before building on it because it may shift once the material decomposes. Doing so will reduce the high cost of foundation repair. 

Sand and gravel

Sandy and gravel soil is formed when rocks like quartz, limestone, and granite break down. This type of soil has large particles, which helps in quick water drainage. Compacted sand and gravel offer stability, reducing the risk of foundation damage. Screw piles are the best foundation technique for this type of soil as they prevent it from washing away. 

  • Rock

Rock is the most suitable for large buildings like skyscrapers as it comprises granite, limestone, hard chalk, and sandstone. The components give rocks high bearing capacity, offering limited risk of fissures and cracks. Rocks also have great stability and depth, making them ideal for foundations requiring minimum secondary repair.  

You can sometimes find an already built house, and it’s upon you to take care of its maintenance needs.  Sometimes, the foundation is one of the areas you should be keen on to prevent the house from collapsing. So, what are the signs of foundation damage?

Signs of Foundation Damage

You need to check for the following signs and act accordingly frequently.

  • Poor water drainage

Poor drainage tops the causes of foundation damage. To check drainage issues & foundation issues, you will inspect the areas around your house for wet soil. The sight of water accumulating around the house signifies that you need to repair the foundation immediately. Leaving foundation water damage unattended will lead to concrete foundation cracks which are costly to repair. 

  • Bowing walls

Bowing walls is a  sign of serious damage that needs thorough house foundation repair. This foundation trouble is caused by the soil shifting beneath the house hence hydrostatic pressure. The repairing process of this damage entails the installation of wall anchors to stabilize the foundation wall and straighten them. To some extent, the foundation contractor may dig some part of the foundation for secondary repair. 

  • Drywall cracks

Also known as sheetrock walls, this damage appears as diagonal cracks on the walls’ interior. In most cases, the small fissures or foundation cracks will come off the window frames and door. However, at times they appear on the stairs—which should be of concern. The root cause of this foundation damage is poor soil quality, gradual structural movement, or unbalanced foundation settlement. 

  • Moisture in crawl space

This is another common foundation damage characterized by a musty smell resulting from mold growth and uneven floor. You can also tell this problem by looking at the pier and beams. Rotten ones are a sign that the foundation is compromised and you need an urgent home’s foundation repair. 

  • Movement of cabinets

Cabinets detaching from the walls is another sign that the foundation needs repair. This gradual foundation movement is caused by the foundation shifting to a different position. The size of the gap can tell the extent of the damage.  

  • Door gaps and sticking windows

Foundation problems can also cause door gaps and sticking windows. The doors will stick or not close properly.  These are signs of a settled foundation that needs leveling. Common causes of door gaps and sticking windows are drainage problems, ground movement, or poor construction. It will be pointless to repair the door or window because the foundation might be sinking. 


Foundation is essential for a stable house, but many don’t know that the soil type affects the foundation most. It will be best to ensure that the construction site has well-drained soil and good bearing capacity. However, if you move into an already built house, it is essential to look for signs of foundation damage. 

Therefore, use the information you have read here when choosing a construction site and checking for signs of foundation damage. However, most of the damages require professional foundation repair contractors. Foundation Maestro is one of the finest foundation repair contractors that can help you with all kinds of foundation repair tasks and lessen the risks of further damage. 

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