Searching for information on how clay soil around a foundation can cause problems? If so, don’t hit that back button because that’s what we’re going to talk about in this article. We’ll review some basic facts about soils and how clay-rich soil can cause problems, discuss a phenomenon known as differential settlement, offer tips on preventing foundation trouble if your home is built on clay soil, and more.
Soils Are Not All Alike
When it comes to building residential homes, or any structure for that matter, soil composition plays a critical role in determining the stability and durability of the foundation. Not all soils are created equal, and the soil type in an area can significantly affect the home’s structural integrity. The three primary types of soil found in the US – sandy soil, clay-rich soil, and sandy loam soil – each have distinct properties that must be considered when designing and constructing homes.
Sandy soil is composed of large sand particles, which make it very porous, lightweight, and well-draining. While this may sound advantageous, sandy soil can be unstable and prone to shifting, causing foundation issues in homes built on it unless measures are taken to stabilize the soil.
In contrast, clay-rich soil is dense and sticky. Due to its high moisture retention, it can swell significantly in wet conditions and then shrink during the dry season, potentially causing foundation damage. Because of this, building on clay-rich soil can be a challenge.
Sandy loam soil
The third type of soil is sandy loam. Sandy loam soil is a mix of sand, silt, and clay, making it well-suited for residential construction as it provides the best balance of soil properties. It’s reasonably well-draining and offers sufficient support for foundations. Sandy loam soil is the preferred choice for constructing buildings.
Clay-Rich Soil Can Cause Differential Foundation Settlement
Differential foundation settlement is a common but significant issue that can impact the stability and safety of structures over time. This type of settlement occurs when some parts of the foundation settle more than others, creating uneven settling and strain on the structure. The illustration below is the easiest way to explain this:
So, what causes differential settlement?
Numerous factors can contribute to differential foundation settlement, including the following:
One of the primary causes of differential foundation settlement is the type and quality of soil underlying the foundation. Different soil types have varying levels of compressibility and load-bearing capacity, which can impact how much settlement will occur and how evenly it will distribute. For example, clay soil has a high potential for swelling and shrinking with changes in moisture content, which causes movement in the ground under the foundation and can lead to differential settlement. However, other soil types can also be prone to settlement.
Soil erosion is another cause of differential foundation settlement. It occurs when the soil beneath the foundation is washed away, leading to weakened support and differential settlement. Soil erosion can be caused by natural factors such as rainfall, flooding or man-made factors such as construction activity.
Inadequate site preparation can also lead to differential foundation settlement. This may include failing to remove vegetation or debris, not properly grading the land, or not adequately compacting the soil before building. Any deviation from established building codes can ultimately lead to foundation issues.
Excess moisture in the ground around a foundation can also cause differential settlement. When water infiltrates the soil under the foundation, it can create areas of saturated soil that may lead to differential settlement. This can occur due to poor drainage, damaged or clogged gutters, or a high water table.
Other Problems Associated With Clay-Rich Soil
Clay-rich soil can expand when wet and push against the foundation walls. This can cause foundation (i.e., basement) walls to bow inward and even crack.
For more information, see What is Expansive Soil & How Does it Cause Foundation Settlement?
How to Prevent Foundation Problems When There’s Clay Soil Around a Foundation
Fortunately, there are several steps homeowners can take to prevent foundation problems when dealing with clay soil around their foundation, including the following:
- Clean gutters and downspouts regularly – Gutters and downspouts are designed to carry water away from the foundation. When leaves and other debris accumulate in gutters and downspouts, they can clog the system and cause water to overflow and soak the ground around the foundation. This excess water adds to the pressure exerted on the foundation by the clay soil, eventually leading to cracks and other damage.
- Use downspout extensions – Installing downspout extensions will divert water several feet away from the foundation before release to prevent the ground around the foundation from getting saturated. Downspout extensions are inexpensive and easy to install.
- Regrade the yard around the foundation, if necessary – The ground around the foundation should slope away from the house to encourage water drainage away from the foundation. This will prevent the clay soil around the foundation from getting saturated with water and swelling.
- Don’t plant water-hungry vegetation next to the foundation – Keeping flowers and shrubs away from the foundation is another crucial step in keeping the foundation healthy if you have clay soil. You don’t want a reason to add water to the ground around the foundation.
- Keep trees away from the foundation – Trees planted too close to the foundation can also cause damage due to their root systems. These roots can penetrate the foundation walls and cause cracks, leaving the foundation vulnerable to damage caused by clay soil.
- Install a drain tile system – Installing a drain tile system is an effective way to prevent foundation problems when dealing with clay soil. This system works by collecting water from around the foundation and directing it away from the house. This helps to prevent ground saturation and reduces pressure on the foundation walls, preventing structural issues caused by clay soil.
Commons Signs of Foundation Problems
Because foundation issues can cause significant damage that can cost a lot of money to fix, it pays to spot them early. Here are some things to look out for:
- Cracks in walls, floors, and ceilings – One of the most common signs of a foundation problem is cracks in walls, floors, or ceilings. These cracks can be horizontal, vertical, or diagonal and may be wider at the top than at the bottom.
- Problems with windows and doors – Another common sign of a foundation problem is doors and windows that are difficult to open or close. This is because differential foundation settlement throws everything out of plumb.
- Gaps around windows and doors – These gaps might be small. However, their presence indicates the foundation has moved.
- Uneven floors – You might not even notice the unevenness at first.
- Chimneys and porches pulling away from the house – These don’t need to be big gaps between the chimney or porch and the house. Even slight gaps are a sign there’s a problem.
- Stair step cracks in brick or masonry – These are a sure sign the foundation has moved.
- Bowed and/or cracked basement wall – This can happen when hydrostatic pressure builds up in the ground around the foundation and pushes against the foundation wall.
If you see any of the above or anything else that strikes you as suspicious, contact a foundation repair contractor right away and ask for an evaluation. By addressing foundation issues early, you can protect your home and ensure your family is safe and secure.
If you’re concerned about clay-rich soil around your home, contact us today to schedule a foundation evaluation. We serve Southern California, Arizona, and Nevada.