Foundation Repair 101: Expansive Soil

The term “expansive soil” may sound self-explanatory, but there is more to it than just soil that expands when rained on. You may have heard the terms “expansive clay” or “heavable soil,” which are two of the several names given to soil containing clay minerals. These minerals include chlorite, bentonite, and vermiculite. These minerals plus many others have the potential to expand. It is because of expansive soil that you should have the soil tested before constructing a home on the property so you can take its composition into account.


Areas of the United States that have high expansion probability include central and northern Montana; North and South Dakota; parts of Nebraska, Colorado, and Wyoming; parts of Texas, Louisiana, and Mississippi; and western Tennessee. There are other clay soils throughout the U.S., but these areas have high concentrations of clay minerals and a very high expansion ability.

How Expansion Happens

Like a dry sponge when moistened, clay minerals expand when they absorb water — and some minerals can absorb a lot. If the soil around your home remains a consistent moisture level, such as by watering it, this isn’t a big deal. But most people don’t water their dirt, and even if they wanted to, many areas with expansive soil are dry, so water allowances are limited.

How Expansive Soil Affects Your Home

Both the expansion and the retraction of drying clay can affect a home’s foundation. When the soil swells from water, that pressure presses against the concrete, which may result in cracks and foundation shifting, among other things. When the clay dries out, it shrinks, which may reduce support for your home. Deep cracks can form in expansive soil, allowing water to run freely around the foundation.

How to Combat Expansive Soil

You can take some measures to mitigate water damage if there are no foundation or basement issues. If it’s feasible, water the soil year-round so it doesn’t go through drastic swelling and shrinking patterns. Make sure your yard from the foundation outward is graded; this means it should slope at a downward angle. Sloping keeps the water moving away from the house instead of pooling next to the foundation.

Install gutters along the back and front edges of the roof. Downspout extensions should angle away from the building and be at least 4 feet long. Keep gutters clean so they can do their jobs. Do not plant trees close to the foundation, and consider root barriers.


Depending on the damage, repairs can range from filling hairline cracks with concrete epoxy to installing steel beams to support the foundation under the expansive soil. Basement and foundation specialists also can install a drainage system appropriate for your home and soil conditions.

Invasive repairs such as installing helical piers (steel beams) can cost a lot of money, so make sure you get more than one estimate from a company specializing in basements and foundations.

To keep your basement as dry as possible on the inside, consider investing in a sump pump with a backup battery pack in case the power goes out during a rainstorm. A whole-house dehumidifier might be beneficial. This is a larger dehumidifier that has enough water capacity to handle an entire home, not just a room.

Acculevel Does It Right

Acculevel has specialized in basements and foundations since 1996, with an emphasis on waterproofing and repairing the damage leaks cause. We find and handle the source of basement floor leaks, cracks, bowed walls, and shifting foundations. Our experts are meticulous and don’t believe in trying to find problems where none exist. We only do what is necessary to fix and/or correct your problem, and we believe in being honest with our clients. If you live in the Midwest, including Indianapolis, and have waterproofing issues such as basement floor leaks, please contact us at (866) 669-3349 or [email protected].

Related Articles:
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What to Do About Unwanted Animals Within Your Foundation
Why You Shouldn’t DIY Your Home’s Foundation
The Connection Between Wet Basements and Foundation Problems

Kelly Kater

Over her twenty year career, Kelly has worked in a wide variety of fields: secondary education, nursing, biology, elder care, the postal service, multicultural development, and academia. She has developed a skill for translating industry-specific jargon into everyday language. Her goal is to share the knowledge and experience of the Acculevel team with homeowners, in a way that is both engaging and informative.

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