Many homeowners assume using high-quality supplies during the early building stages of a home guarantees a solid foundation. That is only partially true.

While the type of equipment used certainly helps keep the foundation strong, it isn’t the only factor that determines the structural integrity of a home’s foundation. In fact, there is a bigger influencing factor: the soil the home is built upon.

How Soil Affects the Foundation of a Home

Not all soil is alike. In fact, there are several different types of soil, all of which have different properties that make them unique. Unfortunately, these distinctive features can dramatically impact a home’s foundation. Some examples of various types of soil that can be found around foundations include:

• Peat
• Silt
• Sand
• Gravel
• Clay
• Loam
• Rock

The soil quality or feature that needs to be considered the most when it comes to home building is water retention. Soil, by nature, is designed to retain water. When this happens, it causes the soil to expand or contract. If a contractor or homebuilder starts the building process without tailoring the project for the type of soil around the foundation and how much water it retains, it could result in an unsteady foundation.

The instability is caused by not creating a foundation design that accommodates the expansion or shrinkage of the soil. Failure to accommodate moisture retention could result in a situation where the soil, when wet, expands and pushes against the foundation. In situations like this, the pressure of the soil will push against the foundation and cause extensive damage.

Soil that absorbs too much water expands, but for certain types of soil the opposite can occur. Some types of soil — such as sand, gravel and clay — will shrink when dry. Soil shrinkage caused by dryness creates space around the foundation. If the space is left for prolonged periods of time, the foundation will start to shift or settle. This creates an instability that will cause various types of damage from cracks in the walls of the home to uneven windows and doors.

Examples of Foundation and Home Damage Caused by Soil

When the soil around foundation is not taken into consideration before starting the building phase, it can cause extensive damage that could leave the structure uninhabitable. Fixing the problems caused by the soil can be costly and time consuming.

Soil does not exclusively produce damage to just the home’s foundation. Other parts of the home — such as drywalls, windows, chimneys and doors — can be impacted throughout the entire structure. After all, the foundation is the base of the structure and if problems happen there, it can spread and compromise the structural integrity of almost any other part of the home.

Some examples of the damage caused by soil around foundation include:

• Tiny, hairline cracks in the drywall of rooms throughout the home
• Fracturing of the basement floor
• Mold or mildew growth caused by damp conditions in the basement
• Doors or windows that do not close properly due to settling
• Water damage from burst pipes
• Extreme shifting of the floors or walls that leaves a home unstable

Using Soil Maps to Better Understand the Soil Around Foundation

It is essential to determine the exact type of soil that is located around the foundation. This information is needed to help builders, contractors and homeowners determine what type of preventative measures can be taken to avoid damage to the foundation or correct any damage that may have occurred.

Looking at the soil will not provide an accurate analysis of what type of soil is present. This is because some types of soil look similar to one another, yet they have different characteristics. In order to accurately determine the type of soil around the foundation, it is best to use a soil map.

Created by the USDA Natural Resources Conservation Service, soil maps will provide valuable information that can help anyone looking to build or repair a foundation on a home.

The information available on soil maps includes:

• Chemical and physical properties of the soil
• Accurate slope of the surface of the land
• Possibility of where water drainage or runoff may happen

Solutions Available to Prevent or Fix Foundation Problems Caused by Soil

Loam and rock are the most ideal types of soil for home foundations. These soil types are sturdy and have a balanced rate of water retention, which allows them to support the added weight of the home without too many problems.

In the event other types of soil are present — such as peat, clay or silt — preventative measures — like installing proper drainage or placing support piers under the home — can be taken to avoid problems. These measures will help prevent the home from settling, or in cases where settling has already occurred, it will help stop any further damage.

Installing proper drainage does not actually stop a foundation from settling. It does divert water away from the foundation and sends it elsewhere. Preventing the water from coming into contact with soil around the foundation reduces the likelihood that the soil will expand and contract due to water retention or dryness. Less expanding and contracting of the soil means less pressure on the foundation, which helps maintain the foundation’s structural integrity.

The other option, support piers, will help create a solid, even surface for a home’s foundation. Installed under the ground, support piers form a solid surface by evenly redistributing the weight of the home. Even distribution of the weight prevents the home from settling.

Before building a home or completing any repairs to an existing foundation, it is important to properly identify the soil that is located around the foundation. Accurate identification of the soil will help prolong the lifespan of a home and reduce potential structural damage by allowing homeowners, builders and contractors to take necessary precautions to guarantee the stability of the foundation.

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