Additional space is always a bonus, but sometimes there isn’t enough room above ground to expand one’s home. In many areas of the United States, basements serve as extra storage space, protection from severe storms, and even laundry or boiler rooms that support the household.
In North Carolina, most houses don’t have basements because it’s difficult to build into the damp soil. Additionally, foundations are generally shallower than a basement requires, and the clay content of the dirt creates extra pressure that can damage underground structures.
Basements that are built in North Carolina also tend to be different than those built in other states. Below are more detailed explanations of why North Carolina homes often lack underground basements.
Frost lines describe how deep the ground freezes in cold weather. In many northern states, this line goes about 5 to 6 feet deep. In North Carolina, however, this frost line is only about 1.5 feet deep.
Foundation supports are typically installed about 2 feet deeper than the frost line to prevent damage from frost heaves. These occur when ice pockets within the frost line displace structures built into it.
Typically, basement walls stand between 7 and 9 feet but can be taller. Fully underground basements require digging at least 7 to 8 feet beneath the ground.
When building homes in places with a deeper frost line of 6 feet, foundation supports will be placed 2 feet beneath that line at a total depth of 8 or more feet. At that point, adding a basement does not require that much additional digging or resources.
However, when the frost line only extends to 1.5 feet or so, the supports will only be installed down to about 3.5 feet. A fully underground basement would therefore require an additional 4.5 feet of digging.
Unfortunately, almost all basements in the U.S. endure water damage at some point—around 98 percent. That statistic practically guarantees a homeowner will need to unexpectedly spend on water damage for their basement at least once under the best of conditions.
Additionally, North Carolina is more prone to flooding because of its heavily saturated earth, making a basement more likely to flood than it would be in a drier environment.
North Carolina is notoriously humid. Even though the ground only freezes down to about a foot and a half deep, much of the state’s soil is heavily saturated far beyond the frost line, meaning that it can’t absorb any more water than it already contains. This moisture presents multiple challenges to constructing a safe underground structure.
There’s a lot of clay in North Carolina soil. Clay expands when wet and impedes excess water from draining out of the ground. It retains a lot more moisture than other dirt particles. And because clay expands when wet, it can press up against and cause basement walls to bow.
If there’s a basement beneath a house, the foundation relies on the integrity of the basement walls and beams in order to remain level and sturdy. When wood rots due to excess humidity, or when that humidity damages the basement structure indirectly, it weakens the foundation and places the house at risk of becoming unlevel or unstable.
Humidity isn’t just uncomfortable. It can foster the growth of molds and other bacteria that can:
- Cause infections
- Aggravate pre-existing conditions, especially those of the respiratory system
- Release substances that are toxic to humans
If a basement lacks adequate ventilation, or if water manages to seep into it over a long time, mold and bacteria can thrive and make the room hazardous to enter.
When a basement is built in a North Carolina home, it is often constructed in a “basement lot” or sloped lot. This means it is built only partially into the ground that slopes at enough of an angle to promote water drainage. In addition, these basements typically have access to the outdoors since they’re partially above ground.
And since some houses are built on sloped lots, it makes sense to fill the additional space that would otherwise go unused despite being the perfect size for a basement installation.
Basements do exist in North Carolina, but they’re uncommon. This is because of the state’s:
- Higher likelihood of flooding
- Shallow frost lines
- Clay-like composition and dampness of the ground
Most basements in North Carolina are built into a slope rather than dug fully underground like classic basements are. Unfortunately, the additional cost for the sake of a bit of extra storage space is not worth the hassle for most homeowners, making basements more burdensome than helpful for many.
If you’re looking for a home in North Carolina with a basement, you can filter the search results on property listing sites. You can also contact a real estate agent with knowledge of the area. Just be prepared for a bit more upkeep.