What Is Soil Washout?: A Cause of Sinking Concrete

What Causes Soil Washout?

Soil erosion is a common event, occurring with each step on your lawn or watering of your flower beds. However, soil washout is a more severe issue. It happens when a water stream rapidly displaces topsoil as it flows down a slope. This is particularly common in high-elevation areas such as inland Virginia, West Virginia, and Maryland, and it requires a slight incline for the water to flow. Residential properties, which are subject to changes in weather and human activity, can easily experience soil washout, especially if they are at least five years old.

• The chemical content of soil, whether it contains certain amount of pollutants, can greatly affect soil cohesion, breaking it down quicker than average and leaving your concrete unsupported. Studies on soil washout identify this as a major factor in concrete damage.
• The terrain, especially around the Appalachian Mountains which divides West Virginia and Virginia, also plays a part. High elevation and sloped terrain enhance soil washout when it rains. Even flatter terrains like Virginia Beach can experience intense washout.
• The type of soil affects how quickly washout occurs. Sandy, fine-grain soils, common in Mid-Atlantic states, do not retain water and wash out easily. They are loose and shifty due to their lack of clay content.
• Tropical storms in Mid-Atlantic states cause significant soil washout due to the heavy rainfall and flooding. This continuous washout happens yearly, from June to November.
• Poor yard drainage can quicken soil washout. A yard with negative grade floods every time it rains, leading to more washout. Even a positive grade yard, where water flows out and away from the house, will experience erosion if the soil is sandy. Investing in a good yard drainage system can help mitigate this issue.
• A lack of foliage can lead to increased soil washout. Plants bind topsoil by dispersing organic material and provide cover from rainfall, blocking water to prevent large streams. In their absence, soil becomes grainier and washes out easily when met with water.

How Soil Washout Affects Your Concrete Sidewalk or Driveway

Soil washout may seem a minor issue but it significantly damages your property’s concrete. It leads to ‘settling’, where erosion under concrete creates an uneven structure. Concrete slabs, typically four inches thick, rely on an even soil layer for support. When soil washout causes this layer to become uneven, sinkholes form. As the slab settles against the sinkhole, it can’t withstand pressure, leading to cracks.

Initially, you might notice a slight wobble or minimal unevenness. Concrete most prone to settling is on an incline, where soil washout is severe. This could affect your driveway or yard pathways, making them difficult to navigate.

How Soil Washout Affects Your Foundation

Soil washout isn’t just a danger to the concrete slabs around your property; it can seriously damage your home’s foundation. Over time, soil washout creates sinkholes, leading to uneven foundation support. This instability triggers structural problems, including:

• Bowing basement walls 
• Exposed foundation concrete 
• Ceiling and wall cracks 
• Jammed doors and windows 
• Stair-step cracks along mortar 
• Tilting chimney  

And in the specific case of slab foundations: 

• Cracked kitchen and bathroom tiles 
• Indoor flooding 
• Chipping floorboards 

If you spot any of these signs, it’s time to call in a professional. Soil washout and the resultant settling can lead to disruptive, increasingly severe structural changes. To avoid a potentially hazardous living situation and costly repairs, stay vigilant for signs of soil washout.

How To Fix Concrete Settling

Concrete settling, a safety hazard and aesthetic concern, is caused by soil washout. However, a simple, innovative solution known as PolyRenewal™ can rectify this issue.

PolyRenewal™ is a quick and efficient method that uses polyurethane foam to combat soil washout. Small holes are drilled into the concrete slab and filled with this foam, raising the slab and filling the sinkhole underneath. The process, which takes under a minute, ensures the slab is level and the foam cures properly.

This straightforward solution goes beyond just lifting the slab; it prevents future settling too. Polyurethane foam, unlike soil or traditional cement mixtures, doesn’t erode over time. It’s waterproof, non-permeable, and doesn’t succumb to the freeze-thaw cycle.

This lightweight yet robust polymer supports over 100 tons of pressure, without displacing the soil underneath. This makes it perfect for loose, sandy soils, like those in Virginia Beach and Roanoke, VA, which can’t support weight without shifting.

Call JES For Your Concrete Lifting Needs

Protect the concrete on your property by calling JES. We’ve been operating since 1993, helping homeowners keep their properties secure and livable. Our service area covers Virginia, Maryland, D.C., and the Outer Banks.

If you’re interested in PolyRenewal­™ for your settling slab, contact us today to set up a free inspection. One of our field agents will assess the damage and give you a rundown of what needs to be done as well as a repair quote.

Michael Wilcher

Michael Wilcher is the Content Lead at Groundworks, helping us to answer all of our customers biggest questions about foundation repair, basement waterproofing, crawl space encapsulation, and concrete lifting. In his free time, Michael enjoys collecting vinyl records, watching Formula 1 Racing, and reading philosophy. He holds an MPhil from the University of Cambridge.

Related Resources

Why Concrete Sinks: The Most Common Causes

Concrete Leveling: What Is It? Do You Need It?

What’s the Best Method for Leveling a Concrete Driveway?

_{*Disclaimer: “Concrete leveling” means the process by which cracked, uneven concrete is stabilized, and in many cases lifted, by means of PolyRenewal™ polyurethane foam. JES Foundation Repair does not guarantee that PolyRenewal™ can make your concrete perfectly level.}