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What Are Expansive Soils and What Problems Do They Cause?

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Expansive soil and your foundation

Expansive soils are widely distributed and costly geologic hazards. Each year, these soils cause more financial loss to homeowners in the U.S. than floods, tornadoes, hurricanes, and earthquakes combined.

Building experts call them hidden disasters, as they’re behind structural damage and home repairs.

While expansive soils are not rampant in St. Cloud, MN, it’s good to know whether the soil below your home has the potential to swell in the presence of moisture. Read on to understand the nature of expansive soils, how to identify them, and measures you can take to protect your home or property.

What Are Expansive Soils?

Swelling soils are a type of soil that is capable of absorbing water. A good example is smectite clay. When these soils soak up water, they expand. Their volumes will keep increasing as they continue absorbing water. Some soils can expand by more than 10 percent.

As the volume changes, the soil starts exerting pressure on buildings and underlying structures resulting in damage. Cracked basement walls, foundations, and floors are typical damages associated with such soils. Significant structural motions can also damage the upper floors of a building.

Why Do These Soils Expand?

Soils are made up of different materials, most of which don’t swell in the presence of water. However, some clay minerals do. These include bentonite, beidellite, vermiculite, chlorite, nontronite, and attapulgite. Sulfate salts in the soil also do expand when temperatures change. Soils that contain expansive minerals have the potential to expand significantly.

Expansive soils don’t have to sound the death knell for your foundation. As long as they retain water or water content remains constant, you have little to worry about. The only time you should be concerned is when the foundation soil loses and gains water repeatedly.

Problems Associated with Expansive Soils

Expansive soils swell during wet spring and summer months, as well as snowy winter months as the ground becomes saturated with water. As soil swells, it exerts tremendous pressure on your foundation walls. The amount of pressure will vary depending on the types of soil, soil moisture content, and the depth of the underlying foundation.

Swelling soils also can lose water during summer months as the ground heats up. Shrinkage can remove the support your building or structure enjoys, causing damaging settlement.

The cycle of swelling and shrinkage underneath the foundation can places stress on structures. Think of how a sponge swells when it absorbs moisture then shrinks as it dries out. After some time, the foundation may crack or develop fissures. Such openings will enable water to leak into the basement when the soil gets wet or there is a runoff.

Signs of Expansive Soils

Not sure whether you’re dealing with expansive soils? Here are five signs that indicate your foundation problems are directly or indirectly associated with swelling soils.

  • Cracks in the basement walls and foundation
  • Sloping or sagging floors
  • Sticking doors and windows
  • Gaps at the sides, bottoms, and tops of doors
  • Drywall cracks

How to Fix Expansive Soils

When the soil starts swelling, you have two options of bringing the situation under control. You can either remove expansive soil completely and replace it will fill dirt or pre-swell the soil and inject it with lime.

These methods attempt to minimize the swell potential and the impact of the soil. However, they’re disruptive and costly.

The problem of expansive soils is best dealt with during ground preparation before construction begins. Before you attempt any repairs, ask a structural engineer to inspect the foundation of your home and whether it’s at risk of settlement or not. Talk to your local foundation repair contractor to explore your options including piering and wall reinforcement measures.

Is Foundation Repair Necessary?

Yes, it is. Bowing, buckling, and cracks in the foundation are serious structural issues that require swift and proper intervention. Left unchecked, these problems can make your home unsafe.

Innovative Basement Authority has skilled and knowledgeable foundation repair experts who can help you resolve the problems associated with expansive soil. We’ve been stabilizing homes on top of shaky soils for over a decade. Get in touch with us for a free foundation repair inspection and quote. Your foundation is in safe hands!

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