What Causes Foundation Settlement? 5 Common Causes
Some foundation movement can happen as a home and the soil beneath it adjust over time. However, problems begin when the soil no longer supports the foundation evenly, causing one area of the home to sink or shift more than another.
So, what causes foundation settlement? Common causes include changing soil conditions, poor drainage, drought, tree roots, and improper site preparation. These issues are especially important in North and South Carolina, where moisture changes affect the expansion and contraction of clay-rich soils.
Carolina Foundation Solutions has helped homeowners throughout the Carolinas identify and repair foundation problems since 2002. In this guide, we explain what foundation settlement is and how to prevent it.
What Is Foundation Settlement?
Foundation settlement is the downward movement of a home’s foundation as the soil beneath it shifts, compresses, erodes, or loses its ability to support the structure.
A small amount of even settlement doesn’t always indicate a serious problem. Uneven or differential settlement is more concerning because one part of the foundation moves differently from another.
Homeowners may notice diagonal wall cracks, sticking doors or windows, uneven floors, or gaps between walls and ceilings. Different types of home settlement can create different crack patterns and warning signs. Horizontal foundation cracks can also indicate foundation stress that deserves professional attention.
The 5 Most Common Causes of Foundation Settlement
Foundation settlement usually begins when the ground supporting your home shifts. Understanding the cause matters because different soil and structural problems can require different solutions.
Common causes of foundation settlement include:
1. Expansive or Poorly Compacted Soil
Clay soil changes volume as its moisture level changes. It expands as it absorbs water and contracts as it dries. Repeated wet-and-dry cycles can create uneven support beneath a foundation.
Poorly compacted fill soil can cause a different problem. If soil placed during construction was not adequately compacted, it can compress under the home’s weight and allow the foundation above it to settle.
2. Soil Erosion from Water Intrusion
Water can gradually carry soil away from beneath a foundation. As soil washes away, unsupported spaces can develop beneath slabs or footings. Parts of the foundation may then settle into these areas.
Poor grading, overflowing gutters, drainage problems, and concentrated downspout discharge can all contribute to erosion around a home.
3. Tree Root Activity and Organic Decomposition
Large tree roots draw water from the ground, which can increase soil shrinkage in areas with moisture-sensitive clay.
Organic material beneath a home can also contribute to settlement. Old roots, stumps, and other buried organic matter eventually decompose, leaving the soil less able to provide consistent support.
4. Drought and Seasonal Moisture Changes
Long dry periods can cause clay-rich soil to lose moisture and shrink. As the soil contracts, it can pull away from the foundation and reduce the support beneath parts of the home.
The next time it rains, the soil can absorb moisture and expand again. Repeated shrink-and-swell cycles can create uneven foundation movement over time.
5. Poor Original Construction or Site Preparation
Your house can settle if the fill soil wasn’t properly compacted during construction, the site had drainage or grading problems, or the footing wasn’t suited to the site’s soil conditions.
Site preparation problems may appear relatively early or concentrate around certain parts of the structure. Additions can also move differently from the original home because they were built at different times and may rest on different soil conditions.
How to Fix Foundation Settlement
The right foundation settlement repair depends on the cause of the movement, the type of foundation, and the condition of the supporting soil. A professional inspection will identify the source of the problem before recommending a repair method.
Helical Piers and Push Piers
Helical piers and push piers can stabilize foundations affected by weak or unstable soil. These systems extend below the problem soil and transfer the structure’s weight to stronger supporting layers.
Helical piers are screwed into the ground, while push piers are hydraulically driven into the soil. The appropriate system depends on the structure, soil conditions, and other site factors. This process is known as foundation underpinning.
Slab Pier Systems and Void Fill
Concrete slabs that have settled can lift and stabilized using slab pier systems. These pier systems transfer the slab’s load to stronger ground below, allowing it to rise back toward its original position.
Polyurethane foam injection can work alongside slab piers to address voids that have developed beneath the concrete. Void fill restores the support needed to maintain the lift after stabilization is complete. In many cases, both methods are used together as part of a comprehensive slab repair.
When to Call a Professional vs. Monitor
Small, stable changes don’t always mean a foundation needs repair. However, new or worsening cracks, sticking doors or windows, uneven floors, visible gaps, or other signs of continued movement deserve a closer look.
Instead of trying to diagnose the cause from a crack alone, schedule a professional evaluation. Carolina Foundation Solutions offers free foundation inspections to identify the problem and determine whether repair is necessary.
Schedule a Free Foundation Inspection
How to Prevent Foundation Settlement
You can’t completely control the soil condition beneath your home, but good drainage and property maintenance can reduce conditions that contribute to settlement.
Here are some things you can do to prevent foundation settlement:
-
Direct water away from the foundation. Make sure the ground slopes away from your home rather than allowing water to collect beside it. Keep gutters clear and direct downspout discharge away from the foundation.
-
Limit major soil-moisture swings. Clay soils expand and contract as moisture levels change. During extended dry periods, maintaining more consistent soil moisture around the home can help limit extreme shrink-and-swell cycles.
-
Watch for drainage problems. Standing water, soil erosion, overflowing gutters, and washed-out areas around the foundation can indicate that water is affecting the supporting soil. Address these problems before erosion worsens.
-
Manage trees carefully. Large trees can affect moisture levels around a foundation. If an established tree sits close to your home, consult a qualified foundation professional before removing it or making major changes around its root system.
-
Track changes around your home. Watch for noticeable changes in cracks, doors, windows, and floors. Dated photos can make it easier to tell whether a crack has stayed stable or is continuing to grow.
Get Your Foundation Checked
If you’ve noticed new cracks, uneven floors, sticking doors, or other changes around your home, you do not have to determine the cause yourself. Carolina Foundation Solutions can inspect your foundation, identify signs of settlement, and explain whether repairs are needed.
Schedule a free foundation inspection today to protect your home year-round.
Foundation Settlement FAQs
What is one of the most common causes of foundation settlement?
Expansive clay soil is a common cause, especially in the Carolinas. Moisture changes can make clay soil shrink or swell, creating uneven support beneath a foundation.
Is it normal for foundations to settle?
Some minor settlement can occur as a home and the soil beneath it adjust. Settlement becomes more concerning when movement continues, worsens, or occurs unevenly across the foundation.
How do you fix foundation settlement?
You can repair foundation settlement with helical piers, push piers, or slab piers. The right solution depends on the cause of the settlement, foundation type, soil conditions, and severity of the movement.
Why is my foundation settling?
Common causes include expansive soil, erosion from poor drainage, drought-related soil shrinkage, tree activity, and poorly compacted soil. A professional foundation inspection can determine what is causing the movement at your home.
