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Expansive Soil

Expansive Soils

Expansive soils can have a seriously negative effect on your foundation, floors, and home overall. Check out what’s causing this soil issue on your property.

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The kind of soil that your foundation sits upon dictates the longevity of a building. Sure, it is impossible for a structure to stay stable forever, but certain types of soil are a lot more destructive than others because they are a lot more expansive. 

As such, it’s no wonder that foundation problems are one of the biggest financial drains for the average American household. Concrete settling, cracks, bent door frames, flooding issues, and other structural damage are largely caused by soil expansion. 

Despite this, there is a lot you can do to work around the soil under your foundation in order to preserve your foundation. Understanding the causes of soil expansion will give you the necessary knowledge to avoid the pitfalls of expansive soils. 

What Causes Soil to Expand? 

expansive soil closeup

When your foundation cracks, becomes displaced and starts falling apart, this is known as settling. Settling occurs when the soil under concrete gives way. Because the concrete no longer has support from the soil, it sinks. This is known as concrete settling. 

But what exactly causes the soil to give way? Soils are made of a variety of materials, some more absorbent than others. Soils that contain more than 25 percent of clay are considered to be expansive soils. It’s because of their clay content that these soils are able to hold so much water and expand upon exposure. 

Expansive soils are able to expand up to 10 percent when wet. Expanding soil on its own isn’t much of a problem. There can be slight issues with the expansive soil putting pressure on whatever concrete it rests against, but it usually isn’t sufficient to do any significant damage unless the concrete is incredibly unsound. 

What does cause problems, however, is soil shrinkage. Just as easily as it expands when exposed to water, expansive soils shrink when all the moisture dries up. As the soil compacts together when it shrinks, the topsoil is diminished. 

When this happens, your foundation is no longer supported by the soil underneath. Your foundation holds up the weight of your home. Without support from the topsoil, it sinks and settles against the soil, which now sits lower than it used to because of shrinkage. 

To avoid concrete settling, you need to avoid getting the soil on your property wet. If you’ve been struggling with concrete settling but are unsure as to how your soil is getting wet, here are some of the things you can check. Discovering how your soil gets wet will help you take the preventative measures needed in order to deter soil expansion.  

  • Yard Grade 

Your yard grade is probably the most important factor when it comes to avoiding soil expansion. Yard grade, also known as lawn grade, is a term used to describe the slope of a property. To avoid water drainage problems, all yards should slope downward slightly so water flows away from the house. If done right, a yard has a positive grade. 

If a yard has a negative grade, it means that water does not flow away from the house. A property with a negative grade will have water pooling around the home. This leads to many foundation issues because water is allowed to seep deeper into the ground and expand the soil. With a negative yard grade, not only is the soil affected but the concrete around the home is compromised as well. 

Landscaping problems that lead to a negative yard grade aren’t even around the entire property, and sometimes, they aren’t very apparent. Some properties only have drainage issues in specific areas and others have an underground negative grade despite the fact that the top lawn has a positive grade. The latter can be very dangerous because it can cause hydrostatic pressure against your foundation walls. 

If you believe your yard has a negative grade, you can contact a landscape grading contractor to examine your yard and re-grade it. You’ll find that once the job is done, your lawn won’t flood every time it rains.  

  • Gutters 

Gutters are meant to collect any rainwater that lands on the roof of your home and guides it away from the building. If a poorly installed gutter isn’t functioning properly, all the rainwater will flow down to your lawn and contribute to soil expansion. 

The same can be said about a clogged gutter. During the fall, it’s important to clean your gutters because any leaves and other debris carried by the wind can block the water from going down the downspout.                                                                 

  • Downspouts 

A downspout directs any water collected by the gutter and points it away from the property. Much like a clogged gutter, a clogged downspout will not be able to guide water efficiently, so it’s important to make sure your downspouts are clear. 

Another thing to consider is the length of a downspout. Some downspouts are too short and dump all the water on your property, sometimes very close to your foundation. If this is the case in your property, you can always extend your downspout so it points away from your home and toward the street.  

  • Sump Pump Issues 

Sump pumps are devices used to pump out any water that pools in a basement or crawl space. A sump pump is a great way to make sure your basement stays dry, but if it has issues, it will affect the soil around your foundation. 

Depending on the issue, a sump pump can cause problems either indoors or outdoors. Most sump pump issues have to do with their ability to collect water in the basement. Without a properly functioning sump pump, a basement with flooding issues will fill with water. The issue that most affects soil is when the foundation drain isn’t working properly. The foundation drain is the pipe that dumps all the water outside, so if the pipe is having problems, it could cause the water to leak into the soil. 

If you have a broken sump pump, you need to get it fixed as soon as possible. Even if your basement isn’t flooding and the sump pump seems like an unnecessary feature, you wouldn’t be able to tell the damage it does to the soil around your foundation. These invisible problems are usually the most harmful to a home’s structure because you don’t recognize that there is a problem until it’s too late.  

  • Poor Basement Waterproofing 

Basements have a reputation for being damp. Many believe that flooding problems and humidity in basements are standard and it’s something you just have to deal with as a homeowner. However, this isn’t the case. Basements can and should be waterproofed for a number of reasons, but the most important one would be for the health of your foundation. 

Concrete is a lot more absorbent than many would believe. When a basement has flooding or leaking issues, all that water damages the concrete. As the concrete ages and more cracks appear, the water seeps through easily, eventually reaching the soil. When it’s time for the soil to expand and then shrink, the foundation, weathered by all the water damage, has an easier time settling. 

To avoid soil expansion, it’s paramount that you waterproof your basement. This means adding new insulation, encapsulating it, and adding a sump pump and dehumidifier if you don’t have one already. All of this may seem like an overwhelming project, but it is worth it in the end, especially if you don’t plan to move from your current home. 

To start, you can always install a window well. It’s a small yet effective way to waterproof your basement. Not only does it prevent water from entering your basement, but it also drains any water away from your foundation. Though it is becoming more common in the industry, not every contractor installs this drain, so it’s something you need to talk to the contractor about.  

  • Rain 

Indiana is ranked 26th in all the United States when it comes to annual precipitation. With a whopping 41 inches of rain each year, the soil on your property gets wet and expands very easily. Of course, soil expansion due to rain is unavoidable, which is why the focus shouldn’t be on preventing soil expansion, but rather handling the amount of water around your property. 

Indianapolis’s rainiest season is summer. During this time, you should make sure that all your sump pumps, gutters, and other drainage systems are in working order. It’s also important to try to minimize the amount of water that lands in your yard. This means you need to turn off the sprinklers, avoid hosing the lawn, and while it may seem tempting because of the heat, avoid setting up an inflatable pool.  

  • Water Table 

Though the soil on your lawn is dry, that doesn’t mean there isn’t any water underground. A water table is a term used to describe the upper surface of the zone of saturation. The zone of saturation is the underground area where the ground is permanently saturated with water. 

Your area’s water table rises with seasonal change. Because it rains most during the summer in Indiana, this is when your soil expands the most, because not only is the surface of the soil getting wet, the water is also coming in from underneath. This is part of the reason foundation problems, settling, and soil expansion is inevitable no matter which materials are used and how much you protect your soil. No matter what you do, moisture will find a way to saturate your soil. 

How Do I Know If My Soil Is Expanding? 

Expansive Soil

Soil expansion is difficult to detect on its own. Expansion, along with shrinking, is something that happens gradually over the course of the year. Unless the construction work was of poor quality, you won’t notice the effects of soil expansion until many years down the line. 

Because soil expansion is a process that mostly happens underground, you’ll be better off trying to find the problem signs throughout your home. The places you should be checking for signs of soil expansion are your basement and crawl space. 

The first thing you must do is make sure that the pipes running along your basement as well as the machinery inside are not leaking, since these issues have nothing to do with expanding soils. Once you’ve determined that everything is in working order, you can begin to examine the walls. Any cracks along the walls, leaking from said cracks, inward bowing and bending, and mold growth are consequences of expanding soil around your foundation. 

While other problem signs do appear around your house, it could be years before those signs show up. By the time that happens, your home will be in such disrepair that it will be a very expensive fix. It’s best to focus on finding issues within your basement and crawl space for more apparent results. Of course, if you want immediate answers, it’s best you contact an expert for a professional assessment. 

Expansive Soils


The biggest threat to your home’s foundation is expansive soil. As a matter of fact, not only is your foundation in danger, if nothing is done about expansive soil, your entire house could suffer some serious damage. You might be wondering why expansive soils are used if they are so harmful. 

If you look it up on a map with the necessary data, you’ll notice that Indiana’s natural terrain doesn’t have a lot of clay soil. And yet, it is still used when building houses. The truth is, expansive soils are widely preferred in the construction trade due to the many advantageous properties they have. In many instances, they are even more beneficial than other, less expansive soils.  

  • Expansive Soils 

When laying down soil as a foundation, it’s important for the workers to be compacted. This means it needs to be firmly pressed together until all the air is displaced. Compaction makes the soil denser and tougher in order to make a suitable foundation for a house. Expansive soils, because of their clay content, compact a lot easier than other types of soils. 

This makes expansive soils great for foundations. Not only are they denser than other soils once compacted, but they are also a lot easier to manipulate. Expansive soils only need to be compacted once before it’s ready while other soils need to be pressed multiple times. Using clay soils saves time during a construction job, which is why it is widely preferred by site managers.  

  • Other Soils 

Gravel and sand, other materials frequently used as the foundation, may seem like a more attractive option because they don’t expand and shrink as readily as clay soils. This is because of their lack of clay. However, this plus comes with a negative. 

Because they don’t compact well, other soils are a lot looser and give way a lot easier. The Midwest is prone to powerful earthquakes, even if they do occur infrequently. This means that any gravel and sand in your foundation shifts around significantly, which causes settling anyway. 

A damp, musty basement that suffers from occasional leaks is seen as the norm. While these issues are common, they are not normal or healthy for your home and family.

With the presence of water and humidity come other issues like mold growth, damaged belongings, structural instability, and more. These threaten the well-being of your loved ones and your entire house.

That’s why waterproofing your basement is essential. There are many repair methods, but the most effective include an interior drainage system, sump pump, wall vapor barrier, and dehumidifier. Working in tandem, these solutions keep water from infiltrating your home and prevent humidity from wreaking havoc.

One of the many dangers of clay soil is hydrostatic pressure. Because clay soils are so porous, water easily seeps through and has the ability to pool in a specific spot underground. This has a profound effect on your foundation.  

  • How Does Hydrostatic Pressure Work? 

Hydrostatic pressure is a term you might be familiar with since it doesn’t apply to construction alone. “Hydro” means water, while “static” is a synonym for motionless. In construction, hydrostatic pressure refers to the damage large amounts of still water have on concrete walls and foundations. 

As soil expands and absorbs more and more water, it flows until pooling along the side of your foundation (since the concrete naturally stops the flow of water). All that water puts an incredible amount of pressure on the foundation. Concrete may seem like a strong material, but it will bend and break against a large amount of pressure.  

  • How Does Hydrostatic Pressure Affect My Home? 

Because so much water is pushed up against the concrete walls, it begins to bow inward. All this pressure slowly breaks the wall down, resulting in many cracks along the wall, warping window frames, and excessive leaking. Things only get worse during the summer because of all the rain: The water that lands on the topsoil adds weight to the water pool against the wall, making the situation worse. 

A positive yard grade and a sump pump are great ways to combat this issue. If you have a negative grade, the hydrostatic pressure is increased because of gravity (since a negative grade means an inward slope). A sump pump will also help with basement flooding. 

Call Indiana Foundation Service for All Your Foundation Repair Needs 

Since 1993, Indiana Foundation Service has been providing innovative solutions for foundation repair, as well as basement and crawl space waterproofing. Over the years, we have developed the best tools of the trade so we can give our customers the best in terms of foundation repair. 

We service Indianapolis, Indiana, and would love to hear from you if you’re having foundation problems. Just give us a call or use our online contact form and we’ll send a field agent to inspect your home in no time at all. The inspection is completely free and our expert will provide an accurate estimate and timeline, so there won’t be any surprise fees when it’s time to get the job done. 

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