Did you know that the type of soil beneath your house plays a critical role in the stability of your foundation? In North Carolina, the most common soil types—clay, sand, and loam—each present unique challenges that can impact your home’s structural integrity. From shrinking clay soil to shifting sandy soil, understanding these soil issues is essential to protecting your foundation. In this article, we’ll explore how these soil types affect foundations and how to prevent or repair the damage they cause.
Understanding North Carolina’s Soil Types
North Carolina’s land is divided into three main regions: the Coastal Plain (45%), characterized by flat to rolling topography with soils ranging from sandy sandhills to wet pocosins; the Piedmont (39%), a rolling to hilly region between the Coastal Plain and the Mountains; and the Mountain region (16%), which comprises the remaining land area.
North Carolina’s diverse geography includes three primary soil types, each with its characteristics:
- Clay Soil: There are two major types of clay: kaolinite and montmorillonite. Kaolinite is the most prevalent in North Carolina. It is relatively stable and exhibits low activity. However, clay soils are known for their ability to retain water. Clay soil types expand when wet and contract when dry. This constant movement can put significant pressure on foundations, leading to cracks and instability.
- Sand Soil: Sandy soil drains quickly, which can lead to soil settlement and shifting as water flows through it. Foundations built on sandy soil are more prone to uneven settling and gaps.
- Loam Soil: Loam, a mix of sand, silt, and clay, is the most stable and versatile soil type. Its balanced texture provides strength and stability, making it ideal for foundations, though poor drainage or water saturation can still affect its performance.
According to NCDA&CS Agronomic Division, Coastal Plain soils are predominantly sandy, while Piedmont and Mountain soils are largely clayey in North Carolina.
How These Soils Affect Foundations?
The soil type in your area can significantly affect the stability and performance of your foundation.
Clay Soil: Expanding And Contracting Pressures
Clay soil absorbs water and expands during heavy rains, exerting pressure on foundation walls. This can cause cracks, bowing walls, and even foundation heaving. In dry conditions, clay shrinks, creating voids beneath the foundation that lead to settling and uneven floors.
According to the Missouri University of Science and Technology, expansive soils significantly threaten light-building foundations across the US. Expansive soils such as clay expand when wet and shrink when dry, creating uplift pressures of up to 5,500 PSF, which can severely damage wood-frame structures. Insurance companies spend millions annually to address such foundation damage. Regions with pronounced wet and dry seasons, especially arid areas, are most vulnerable due to the recurring shrink-swell cycles that crack footings and distress floor slabs.
The presence of just 5% clay by weight can influence soil behavior, with montmorillonite clay causing the most severe effects. Fortunately, kaolinite, the more stable clay type, is more prevalent in North Carolina. However, clay is still clay, and it will still cause problems if not properly managed.
Sand Soil: Shifting And Erosion
Sandy soil is inherently prone to shifting, and its drainage properties amplify this tendency, creating significant challenges for building stable structures. The granular nature of loose sand allows for rapid and substantial settlements, often requiring densification to provide adequate support and control for foundations in new construction projects.
One advantage of sandy soil and foundations is its low susceptibility to frost due to its coarse, free-draining properties, according to the US Department of Agriculture. Unlike finer soils like clays, silts, or very fine sands, sandy soil does not readily support the formation of ice lenses, which cause frost heaving and can damage foundations.
Loam Soil: Generally Stable But Not Immune
According to Science Direct, typical loam soil comprises approximately 50% solid particles—a mix of sand, silt, and clay—and 50% pore spaces filled with air and water. Loamy soils generally provide stable support for foundations due to their favorable structure and drainage properties. They are less prone to shifting or settling compared to pure sandy or clay soils, but their performance depends on their composition. High clay content can lead to moisture retention, shrink-swell cycles, or water pooling, while proper compaction ensures even weight distribution and stability. Overall, loamy soil is suitable for foundations if its drainage and compaction are carefully managed.
Signs Of Soil-Related Foundation Problems
Soil-related foundation problems can develop gradually, making early detection crucial to protecting your home from significant structural damage.
The following signs are common indicators that the soil beneath your home is affecting your foundation’s stability:
- Cracks in walls, floors, or ceilings
- Doors and windows are stuck or no longer close properly
- Uneven, bouncy, or sloping floors
- Water collecting near the foundation after heavy rains
- Gaps between walls and floors or between the foundation and the ground
- Cracks in a stair-step pattern along brick or block walls or bowing walls
- Leaning chimneys
- Foundation settlement or sinking in specific areas
- When a foundation rises due to soil expansion or water pressure
- Cracks in drywall, particularly around corners, doors, and windows
- Cabinets pulling away from walls
Solutions For Soil-Related Foundation Problems
Regional Foundation & Crawl Space Repair provides expert foundation repair and basement waterproofing solutions tailored to combat the challenges posed by North Carolina’s diverse and unpredictable soil conditions.
Here’s a deeper look at these solutions:
Foundation Crack Repair
Cracks in the foundation are often the first visible sign of soil-related problems. RF uses specialized materials such as epoxy injections or polyurethane foam to seal cracks. This process not only prevents further structural damage but also helps to eliminate pathways for water infiltration, which can worsen soil-related issues by causing expansion, contraction, or erosion.
Underpinning And Pier Systems
Shifting or settling soils can compromise a foundation’s stability. Underpinning techniques, like installing steel push piers or helical piers, transfer the home’s weight to deeper, more stable strata. This method restores the foundation’s stability, prevents further sinking, and often lifts the structure back to its original level.
Drainage Improvements
Poor drainage exacerbates soil problems by promoting water accumulation around the foundation. Regional Foundation & Crawl Space Repair offers comprehensive drainage solutions, including:
- Drains to redirect groundwater away from your foundation.
- Downspout Extensions to prevent roof runoff from saturating the soil near the home.
- These measures reduce soil erosion, mitigate water pooling, and minimize pressure against the foundation walls.
Moisture Control
Moisture is a significant factor in soil expansion and contraction, particularly with clay soils. RF implements strategies like:
- Vapor Barriers to help prevent moisture from the ground from infiltrating crawl spaces or basements.
- Dehumidifiers to maintain a consistent indoor humidity level and protect the home from moisture-related issues.
- Sump Pumps to actively remove water from the basement or crawl space, ensuring that excessive moisture doesn’t compromise the foundation.
Why Choose Regional Foundation & Crawl Space Repair?
At the Regional Foundation & Crawl Space Repair, we understand North Carolina homeowners’ unique challenges due to the region’s diverse soil types, including clay, sand, and loam. These soils can cause foundation issues like settling, cracks, or water infiltration, threatening the safety and stability of your home. Our experienced team specializes in diagnosing these problems and tailoring effective solutions that address the root cause of your foundation concerns.
We use advanced repair techniques and durable materials to ensure long-lasting results. Whether it’s installing underpinning systems, improving drainage, or stabilizing problematic soils, we’re committed to providing solutions that protect your home and give you peace of mind. With the Regional Foundation & Crawl Space Repair, you can trust that your home is in expert hands.
Real-World Example: Stabilizing A Foundation On Clay Soil
North Carolina’s diverse soil composition poses unique challenges for homeowners. Clay soils, prevalent in many areas, are particularly problematic. These types of soils expand when wet and contract when dry, causing significant pressure changes on a home’s foundation.
Anthony, a North Carolina homeowner, faced foundation instability caused by expansive clay soil. “I had seventeen piers installed to stabilize my foundation,” Anthony shared. Despite challenging conditions, including a day of rain, the team completed the project efficiently. “Doug, TJ, Matt, and Ubaldo managed to knock it out in a couple of days, even with my clay soil.”
This case highlights the importance of tailored solutions and expertise when addressing soil-related foundation problems. Proper stabilization not only secures the foundation but also prevents future issues caused by North Carolina’s unpredictable soils.
Protect Your Foundation From Soil Issues
Don’t let soil-related problems compromise your home’s stability. Whether you’re dealing with shifting sandy soil, expanding clay, or water pooling around loam, Regional Foundation has the expertise to protect your foundation. Contact us today to schedule a foundation inspection and learn how we can address your soil challenges.
