Why Do Foundations Sink and How Are They Repaired?

Media clips of giant sinkholes opening up under a house or car may have you thinking that’s the only way a foundation will sink—dramatically and suddenly. However, a normal sinking foundation isn’t caused by a sinkhole, and it takes a while for a foundation to noticeably sink. If you do notice after the fact, it’s likely because you missed or ignored the warning signs.

How Does Sinking Start?

Sinking is all about water pressure, soil pressure, and soil shifting. When a foundation is first installed, dirt is tamped and concrete is poured. No matter how hard the dirt is compacted, it still has pockets of air and can move around. An earthquake may shift the dirt itself, but the most likely culprit is water and temperature changes. When water seeps into the soil, the soil expands, pushing against the foundation. Water also causes the dirt to move around (shifting) and channels through the soil, opening pockets into which soil falls.

Floods, drought, and snow all affect soil around a foundation. Flooding saturates dirt and can turn it into what amounts to a slurry. The water doesn’t liquefy the soil, but it does get between all the grains of sand and makes the soil as runny as water. During an earthquake, if the soil is completely saturated, the shaking may turn soil into a slurry.

Drought sucks moisture from soil, which makes the dirt shift. If you have clay soil, drought really does a number on it. This is why it is important to keep the soil moisture around the foundation as consistent as possible throughout the year. If you can, add moisture to clay soil if it starts to dry our and crack.

Snow and freezing temperatures can create frost heaves. This is when water from melting snow freezes, expanding the soil around it. Frost heave can affect driveways and sidewalks as well as the foundation.

Warning Signs

Cracks along the foundation or basement walls and bowed walls are the most obvious signs your foundation is not level. Signs that are subtle and may be missed include doors that stick, unleveled doorframes, cracks in the ceiling, window cracks, and sagging floorboards.

Repair Options

The first item to address is how to control the water issues. A professional foundation specialist will talk to you about internal and external drainage systems, sealing any cracks, reducing moisture in the air as well as ways to actually lift the foundation if that is needed.

Specialists can reinforce or lift a foundation a few ways. It is called “slabjacking” when professionals drill small holes into a concrete foundation and pump in expanding foam. This foam fills any pockets in the soil underneath the foundation, stabilizing the foundation.

Helical piers and tie-backs are attached to the outside of the foundation to prop it up. A crew will dig deep into the ground to find soil that is stable, drive the piers into the ground, and attach them to the foundation.

After the foundation is straight, it might be necessary to install carbon fiber straps or wall anchors. Both these items are for additional support along the basement walls. Carbon fiber straps are bonded to the walls via a strong epoxy. Wall anchors involve metal plates in the wall to which steel beams are attached.

Acculevel Handles the Repairs for You

While we have total respect for the amazing handymen and women who can repair almost anything around the house, repairing the foundation of your home should be done by specialists skilled in foundation repair. At Acculevel, we have focused on basement and foundation repair since 1996. Our experienced staff can handle all waterproofing issues, and we will not try to fix something that isn’t broken. If you live in the Midwest and your foundation is shifting or you have water leakage in your basement, feel free to call us at 866-669-3349 or email us at [email protected].

Related Articles:
Why You Shouldn’t DIY Your Home’s Foundation
The Connection Between Wet Basements and Foundation Problems
Foundation Repair 101: Expansive Soil
Garage Floor Foundation Repair
Will Foundation Repair Affect the Resale of Your Home?
Are Foundation Repairs Tax Deductible?

Kelly Kater

Over her twenty year career, Kelly has worked in a wide variety of fields: secondary education, nursing, biology, elder care, the postal service, multicultural development, and academia. She has developed a skill for translating industry-specific jargon into everyday language. Her goal is to share the knowledge and experience of the Acculevel team with homeowners, in a way that is both engaging and informative.

    Stay In Touch

    Get Email Updates

    Sign up for email notifications about new articles.