What Are The Signs Of Foundation Heave?

As homeowners, the integrity of your living space begins from the ground up – quite literally – with the foundation. It’s the bedrock of your home’s structure, but what happens when the very ground it rests on becomes an unpredictable force?

In this article, we’ll cover the signs of foundation heave and what you can do if you suspect your home is experiencing this phenomenon.

But first, let’s understand what foundation heave is.

What Is Foundation Heave?

A heave means ‘to be pushed up.’ So, the foundation of a structure is being pushed up.

According to Forensic Engineers Inc., foundation heave is the upward movement of a structure’s foundation, usually caused by the expansion of the soil underneath it. This phenomenon can occur when the soil’s moisture content increases, leading to an increase in volume or swell. Heave typically happens in clay-rich soils, which possess a strong capacity to draw in water and are exposed to a source of moisture.

In most cases, it is not your whole house being pushed up, but parts of it making the structure experience uneven or differential movement. This can lead to various structural issues within the building, such as cracked walls, uneven floors, and misaligned doors or windows. In extreme cases, it requires immediate foundation repair.

What Are The Signs Of Foundation Heave?

Foundation heaving is not easily noticeable and can be hard to predict. But how do you know if your house is experiencing foundation heave?

Here are some signs to look out for:

• Slab cracks that resemble chicken feet, spider webs, or a triangle. There should be at least two intersecting cracks.
• Trees nearby are showing signs of distress. Then, after a year or two, they were felled or died.
• Other flatworks near the foundation, like driveways, shifted upwards and away in relation to the foundation.
• Doors and windows are misaligned or off-center.
• Door frames, window frames, drywalls, and brick, block, and stone walls are cracking.
• Floors might become uneven, slope in one direction, or feel bouncy and less solid.
• If your building has expansion joints, you may notice that these joints begin to separate or widen.
• Poor drainage or water pooling around the foundation can be both a cause and a sign of potential foundation heave.
• The plasticity index (PI) of the soil exceeds 25.
• The soil’s moisture content (MC) beneath the foundation has been rising over recent years.

Keep in mind that not all of these signs will be present in every case. Only a few of these signs will likely be present, and they may not all occur simultaneously.

Common Causes Of Foundation Heaving

So, why do foundations heave? What are the common causes?

Here are the possible reasons:

• Expansive Soils: Soils, such as clay, expand when exposed to water and shrink as they dry out. This expansion and contraction cycle can exert upward pressure on the foundation, causing it to heave.
• Improper Drainage: Poor drainage around your home can lead to water pooling near the foundation. This excessive moisture can be absorbed by the soil, leading to expansion and subsequent heaving of the foundation.
• Frost Heave: In colder climates, the freezing of groundwater can also cause foundation heaving. According to the Lunar and Planetary Institute, water expands approximately 9% by volume when frozen. When water in the ground freezes, it expands and can push the foundation upward. This typically happens in poorly drained soils where water can accumulate and freeze.
• Leaking Pipes: Water leaks from plumbing systems can saturate the soil under and around a foundation, causing localized heaving due to soil expansion.
• Tree Roots: When planted too close to a structure, trees can also cause foundation problems. As roots grow and search for water, they can dry out the soil under a foundation. It can lead to differential movement and possibly heaving if the soil subsequently rehydrates and expands.

Different Types Of Foundation Movement

There are different types of foundation movements that might cause foundation problems.

Foundation Settlement

A settlement is the downward movement of the ground supporting a structure. It often occurs when the soil compresses due to the weight of the building. All new homes typically experience a small amount of foundation settlement within the first few years as the soil adjusts to the new load placed upon it.

The settlement itself is a natural process and does not necessarily result in structural damage if the building settles uniformly. However, differential settlement can cause cracks and structural damage.

Foundation Heaving

Heaving, on the other hand, refers to the upward movement of the ground beneath a property. It is usually due to the expansion of the soil. This can occur for several reasons, including the rehydration of previously dry soil, the freezing of groundwater, or the removal of trees, which can cause clay soils to expand. Heave can lift a building’s foundation unevenly, causing structural problems similar to those caused by excessive settlement.

Foundation Subsidence

Subsidence is the downward movement or sinking of the ground beneath a structure without any imposed load. Foundation subsidence often occurs when the soil beneath a building’s foundations is unstable. This can be caused by various factors, including the drying out and shrinkage of clay soils, leaking drains, washing away or compression of soil, and mining activities.

Unlike settlement, which is a normal response to the weight of a new building, subsidence can point to an external problem, causing the ground to collapse or a void to form under the foundation, potentially leading to significant structural issues.

Foundation Heave Solutions

If your foundation is heaving, it’s important to address the problem as soon as possible. The longer you wait, the more damage can be done to your home, and the more expensive repairs will be.

There are three remedies for foundation heaving.

Moisture Control

The first step in preventing foundation heave is to control the moisture content of the soil around your home.

You can do this through the following methods:

• Removing nearby water sources that might be causing the soil to expand.
• Repair leaking pipes or sewer lines.
• Install proper drainage systems.
• Try using a moisture retarder.

Let It Be

In some cases, if the heave is not severe or causing significant structural damage, one approach can be to simply monitor the situation.

This method is more about management than direct intervention:

• Monitoring: Keep an eye on the movement and cracks to ensure they do not worsen over time.
• Waiting: Sometimes, the soil and foundation may stabilize on their own, especially as moisture levels even out over time.

This second approach requires patience and a willingness to accept some degree of uncertainty, relying on the natural stabilization process of the soil and structure.

However, if the heaving exceeds the acceptable limits, then you have to repair your foundation.

Foundation Repair

If you have determined that your foundation is in need of repair, there are several options available to you.

• Underpinning: This method involves extending the foundation depth or width to more stable soil or bedrock not affected by moisture changes. This might include the use of piers, such as helical piers or concrete piles, to provide additional support.
• Polymer Injection: You can stabilize the soil by injecting a polymer into it. This innovative technique is used to solidify soil and resist water infiltration.
• Mudjacking or Slabjacking: This process can lift a sunken slab back to its original position. A mixture (usually a mud/slurry mix) is pumped under the slab to raise it, aiming to return the foundation to a more acceptable elevation and stability.

These foundation repair methods require a professional to inspect, determine the best course of action, and perform the repair.

If you live in the Triangle, Triad, or Eastern North Carolina, our Regional Foundation & Crawl Space Repair team is here to help. We have the experience and expertise to repair your foundation, whether it’s a minor issue or a significant problem.

Contact us today to schedule a free inspection and estimate.