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How Dry Soil and Rain Cause Foundation Problems

dry, cracked soil around the foundation of a house

Soil stability is the biggest factor in your foundation’s health. Two major factors in soil stability are dried-out soil (in other words, drought) and rain. When you get too much of one and not enough of the other, it can spell trouble for your foundation. But how do you fight back against those natural elements that are far outside of your control?

Tar Heel Basement Systems is one of the leading foundation repair companies in North Carolina, serving homeowners from Winston-Salem to Wilmington. You can rely on our decades of experience fighting against the elements and addressing soil conditions that spell impending foundation problems.

In this article, you learn how drought and rain affect your foundation and what you can do to prevent or repair the resulting damage. You can also learn more about our foundation repair services or get help now by clicking the button below to schedule your free inspection.

How Rain and Drought Affect the Soil Around Your Foundation

It goes without saying, the soil under your home is important. Your entire home depends on it. Your foundation is built into the top layer of soil, and so if there’s a problem down there, you’re going to see its effects on your home.

You might be surprised to learn that this top layer of soil is actually always in motion. On the whole, this motion is very slow, but over a number of years it’s almost guaranteed to to act on your home in very distinct ways.

How the Soil Beneath Your Home Shifts and Settles

The natural cycles of drought (or even just relatively dry conditions) and rain are the biggest forces that set soil in motion. Here’s how:

  • When it rains, the soil expands as it soaks up the water, increasing the hydrostatic pressure on your foundation.
  • When conditions warm up, the water evaporates and the soil shrinks, lessening the pressure around your foundation.
  • When the soil gets almost completely dry, the soil can become brittle and form gaps (pictured here), decreasing support to your foundation.
  • When it rains again, the water fills these gaps, adding even more pressure to your foundation than before.

Most Common Foundation Issues Caused by Soil Movement

Over time, this cycle of wet and dry soil moves your soil all around, causing a few major issues that damage your foundation. Here’s a quick list of the things that most often happen.

1. Foundation Settlement

Foundation Settlement

Foundation settlement (AKA “differential settlement”) often results from the movement of the soil due to changing moisture levels. Here’s why:

  • The soil under your foundation is comprised of several different layers, and some of these layer were dug up when your foundation was laid.
  • The dug-up soil is backfilled once the foundation is in place, but it’s less dense than the soil around it. This creates a “Clay Bowl Effect” which means water more likely to collect around your foundation than elsewhere.
  • Between the twin forces of the dug-out soil layers drying out and water filling them up again, your foundation will sink and settle.

2. Foundation Heave

Foundation Heave

Foundation heave is the alter ego of settlement. It occurs when one side of your foundation begins to sink and the other side is either slightly raised or else just appears to be raised up higher than the other side. The clearest sign of this is an uneven floor. Foundation heave will also cause cracks in floors, bowing walls, and sticking windows and doors.

One easy way to spot heave is to examine floor cracks and see if they form an enclosed loop (pictured here). The area inside that loop is where the greatest pressure is being exerted.

Soil Expansion and Shrinkage in North Carolina

This cycle of drought and rain is especially pronounced in regions of the United States, especially North Carolina, that feature a significant amount of clay in the soil. Soils like this are especially prone to expanding with water, sometimes increasing in volume by 10% after a substantial rain. Likewise, they shrink a lot faster and to a more pronounced degree. 

In North Carolina, Cecil soil is the most common type of soil, spanning 1.6 million acres primarily across the piedmont region including Raleigh, Durham and Winston-Salem. Cecil soil has a large amount of red clay deposits that are great for agriculture, but not so great for your home.

How to Know If Soil Is Causing Foundation Problems

Large crack on house exterior near window

While you may not be able to look underground to survey the soil in motion, but you may notice damage in your everyday life through these common problem signs: 

How To Prevent Further Foundation Damage from Soil

The first rainfall after a drought is a pivotal time for the structural soundness of your foundation. Without the right preparations and support set in place, you could face in-home flooding, leaking, and even mold. 

1. Clean Out Your Gutters And Drains 

Rearing up for the first substantial rain, you’ll want to make sure your existing drainage systems and gutters are clear and well-equipped to take on the long-awaited water. Ensure to routinely clear out leaves, brush, nests or critters. 

2. Install Sprinklers  

If there are no local restrictions or rationing of water, it will help your foundation and home landscaping to prime your lawn, even with a little bit of water. This will help you keep an eye on water grading around your home and help ensure that water drains away from your home’s foundation and doesn’t pool. 

3. Install Drywells 

Drywells are underground drains used to safely dispose of excess runoff water or storm water away from the home. This type of drainage system specifically benefits homes that suffer from negative grading (water flowing toward your home instead of away from it). Drywells are installed close to the home where it collects water and drains it to a place far from the home. 

4. Invest in a Foundation Drainage System 

A sub-surface drainage system, such as a sump pump in your crawl space or basement, is an underground system that removes water from within and underneath your home’s foundation. These systems are vital especially during a flood, which is possible during the first rain after a drought due to the previous shrinkage of soil and structural damage your home may have endured. 

5. Install a Dehumidifier in your Basement or Crawl Space 

Since the soil beneath your house has been without moisture for a while, the lower levels of your home may not currently suffer from excess moisture levels. When rain falls once more, moisture may have an easier way inside your home. Dehumidifiers work to control the levels of humidity your basement or crawl space experiences.

How to Repair Foundation Soil Problems

If you suspect foundation damage after a drought, acting quickly can make or break the structural integrity of your home. Since foundation problems only worsen with time, installing preventive measures or correcting foundation issues early on can save you money and stress in the long run. 

Determining what’s going on with your home is the first vital step in preparing or repairing it from the stress of drought. Tar Heel Basement Systems offers free inspections with a no-obligation quote, so you can make the best decision for your home. 

As professionals who specialize in foundation repair and protection, we take pride in providing these solutions for your home. 

Our goal is to give you the right repairs once, so you can have peace of mind through rain or shine. Call the experts at Tar Heel Basement Systems today to set up your appointment. 

What Will Happen to Your Foundation After a Drought Ends? 

First, it’s important to know what indicates the end of a drought. A small drizzle is not substantial enough to end a drought, as it’s quickly soaked up by the local plant life, then evaporated. A drought is over when soaking, heavy rain falls for long enough to deeply quench the soil and re-energize the ecosystem. 

If underground soil pockets formed beneath your home, these could fill with rainwater, expand the soil, and potentially exert hydrostatic pressure on your basement or other foundation type. 

Due to the change in the soil around your home after the drought, water may also drain differently. Worst case scenario, it will grade negatively toward your home and puddle, as opposed to being directed away. This makes your basement, crawl space or the interior of your home more prone to flooding. Poor yard drainage may also exasperate hydrostatic pressure in the soil around your home. 

Foundation Soil Damage FAQs

When concrete settles, cracks, deteriorates, and splits, there are many possible causes. The circumstances leading up to concrete settling all play a role that affects the severity of the settling. The freeze-thaw effect is something that impacts concrete as much as soil shrinkage does, but the two incidents shouldn’t get confused. 

  • Understanding the Freeze-Thaw Effect  

When rain falls on concrete, it can freeze over and turn into ice. When water freezes, it expands by about 9%. The expanding water creates pressure on the concrete’s pores, and if the pressure exceeds the concrete’s tension limits, it will break apart the concrete. This is how some concrete surfaces manage to deteriorate over time despite not settling. This, of course, happens in places where temperatures reach freezing levels. 

Over time, the freeze-thaw effect does influence settling in the sense that, upon weakening the concrete and eroding the surface, the concrete gives way faster when it settles. However, it does not cause settling—at least, not as much as soil shrinkage does.  

  • How Is It Different from Soil Shrinkage?

Water that reaches the soil underneath concrete can freeze over and affect the soil. However, it doesn’t affect the soil the same way soil shrinkage does. When the water freezes and expands, it pushes the soil particles outward and separates them, similarly to how moisture makes soil swell up. 

When the ice melts and dries up, shrinkage occurs. However, this process is no longer considered freeze-thaw. The moisture may have been ice at one point, but shrinkage does not take place when ice is involved, only moisture. 

Whether it’s high humidity or unstable basement walls, the clay soil around your property is the cause of a lot of issues. When repairing something, especially if it’s related to home improvement, it’s always important to tackle the source of the issue. So, if clay soils are causing so much trouble around your home, could it be replaced with a soil that has less clay in it? The truth is, no matter what kind of soil you have around your foundation, there will always be some issue with it. No matter how many years of perfecting certain building techniques and inventing useful tools that makes construction easier, humans cannot control the way the elements react to one another.

Soils with less clay in them are lot more granular; they do not compact as well as clay soils do and tend to shift around a lot easier because of it. Soil that shifts easily does not always make for good foundation soil, especially in the Piedmont Triad area. North Carolina is a very rainy state, so the soil would wash away eventually due to the floods and rainfall. Not to mention, the Triad Area is right in between the New Madrid Seismic Zone and the East Tennessee Seismic Zone. The earthquakes from these two regions do ripple through towards cities like Greensboro and Winston-Salem and affect the soil.

Replacing the soil around your foundation would mean having to lift your home, dig a deep hole, replace the soil, and rebuild the foundation. Not only would this be incredibly expensive, it would also be incredibly unnecessary. Even if you wanted different soil just to have better yard drainage, there are better steps you can take. A simpler, more effect solution would be to waterproof the foundation and repair it when needed.

Every crack in your foundation or walls should warrant some concern, no matter how small. It almost always spells foundation issues. Horizontal, diagonal, and stair-step cracks growing in width and gaps around windows and doors should be examined. Those that accompany bowing walls and uneven floors are of even more concern. It may also be helpful to note that if you live in a coastal area of North Carolina with sandy soil and rising sea levels, you may be at higher risk of foundation issues.  

Seeing Signs of Foundation Damage? Call Tar Heel Basement Systems!

If the recent drought is causing you to see any of these foundation or wall issues, please contact a foundation repair specialist. There are steps that can be taken before the problem worsens and total foundation replacement is needed.

Let our foundation repair experts help

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Crew installing push piers

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Michael Wilcher

Michael Wilcher

Michael Wilcher is the Content Lead at Groundworks, helping us to answer all of our customers biggest questions about foundation repair, basement waterproofing, crawl space encapsulation, and concrete lifting. In his free time, Michael enjoys collecting vinyl records, watching Formula 1 Racing, and reading philosophy. He holds an MPhil from the University of Cambridge.

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