6 Common Causes of Foundation Settlement

Marwa Hasan
Written by Marwa Hasan
Updated October 13, 2021
The exterior of a colonial house on an autumn day
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Keep an eye out for warning signs

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If cracks seem to spring up on your walls or your windows and doors are suddenly hard to properly shut, these might be signs that your foundation is settling. 

Every home may experience foundation settlement over time, especially in the years right after construction. While sometimes it’s nothing to worry about, it could become more severe if left untreated—and even compromise your house’s structure.

What is Foundation Settlement?

The reasons behind your home’s settlement are rarely due to the foundation design itself, but because of changes happening in the soil. 

When the soil supporting the foundation shifts or changes beneath your home, the foundation moves, potentially compromising the structure. Identifying the reasons why it’s happening can allow you to prevent the foundation from settling

Here are some of the reasons why houses experience foundation settlement.

1. Drying Soils

During dry summer months, the soil around your foundation may begin to dry. Clay soils in particular shrink when they dry, creating a void between the structure and the soil. When this happens, your foundation settles, frequently resulting in structural damage.

Another reason for drying the soil could be a leaky HVAC system in the subfloor.

2. Poorly Compacted Soil

When it’s time to prepare the lot for your home’s foundation, usually builders will use soil from another location to fill any hollow areas or gaps. To make sure the soil is suitable for the weight of the building, builders compact the soil using heavy equipment before placing the foundation. 

If the soil hasn’t been compacted properly, it won’t give the foundation adequate support, leading to foundation settlement issues.

3. Soil Type

The type of soil around your foundation plays a big role in how it supports the building. For example, clay soil is expansive—it expands and contracts like sponges with water. Sandy soils, on the other hand, drain better. 

Some types of soil are just not conducive for supporting the weight of a building. Foundation settlement or differential settlement happens when builders don’t pay attention to the location’s soil composition, so they won't accommodate the foundation to the type of soil underneath it.

4. Moisture-Filled Soil

When the foundation’s soil is saturated with water, it can easily result in settlement. Moisture from heavy rain, flooding, a plumbing leak, or a raised groundwater table can oversaturate the soil and potentially weaken its load-bearing capacity.

Water pushes soil out from under the home, creating a void that can sink a house or building. When the water freezes, the soil will expand and bring it close to the surface. This is why proper site drainage is essential to ensure the subsoils maintain as close to uniform moisture content as possible throughout the year.

5. Vegetation

The backyard of a house with large trees
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Plants, trees, or any other types of vegetation near your home can cause foundation settlement. 

Growing tree roots will catch moisture from the soil because they’re always searching for water, causing the soil to dry and shrink. It can take several decades before this type of problem becomes visible, and settlement is more likely to happen with shallow foundations than basement-level or deeper piers extending down many feet.

6. Vibrations

The vibration of the soil from seismic activity, trains, structural work nearby, or even from traffic can cause soils to settle or shift unevenly, leading to structural damage to the building.

How to Deal with Foundation Issues

When you start seeing signs of foundation problems, you need to address them ASAP.

Dealing with a settling foundation quickly is the best way to save the structural integrity of your home and allow it to stay in good condition for many years to come. Whereas, if you don’t address the problem, it will get worse, causing further damage in the process.

A local structural engineer will examine the site, diagnose the problem, and start working on foundation repairs such as installing new footings, adding rain gutters, or fixing leaky pipes. In other cases, the structural engineer may monitor the settling while maintaining the foundation and addressing superficial cosmetic concerns.

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