When a concrete slab settles, it’s usually not because of a problem with the slab itself. Because the concrete slabs on your property rest upon a layer of soil, if that layer becomes uneven in any way, the slab will settle. If you’re a homeowner living in Virginia, West Virginia, or Maryland, then soil washout may be compromising the integrity of your concrete slab.
Soil washout is the sudden erosion of topsoil due to a stream of water. When a gush of water runs down the surface of a layer of soil, it displaces the particles and washes the soil away, creating gaps. Even when under a slab, soil can experience washout and displacement.
Due to soil washout, concrete slabs no longer have the support of the soil underneath it, so they sink to the ground. This creates an uneven path, since the slabs usually settle unevenly, and not all slabs settle at the same time.
Concrete settling is a major safety risk, since anybody can trip on uneven paths. Learning more about soil washout, when it occurs, and how to spot the signs is crucial for keeping your property safe for you and your family.
Signs That Your Soil Is Washing Out
Spotting the signs for soil washout isn’t as straightforward as you would expect. Soil washout occurs under the slab where you wouldn’t be able to see it, so it’s not as easy as simply seeing the water erode the soil. The signs that indicate soil washout can sometimes be subtle and indirect, so take some time out of your day to thoroughly inspect your home.
Concrete Slab Settling
The most obvious sign that the soil on your property has eroded is concrete slab settling. This can happen in your patio, garage, walkways, and pool deck. Any kind of unevenness indicates a problem with your slab’s foundation.
You might think that water would not be able to reach soil while it’s underneath a concrete slab, but you would be surprised. Concrete slabs are typically only four inches tall and concrete itself is a very porous material. Every time the slab is exposed to water, it absorbs it and the moisture seeps through to the soil below the slab. Let’s not forget that concrete isn’t completely solid and smooth, and it cracks over time. These cracks make it easier for moisture to permeate through the slab.
Concrete slabs that are most likely to experience settling are those that are next to the exposed soil in your yard. This is because water is able to flow under the slab a lot easier through the edge of the slab.
Even if the slab doesn’t seem uneven, if it wobbles when you step on it, it is settling. Concrete settling only gets worse with time, so call a concrete lifting expert at the smallest sign of settling.
Yard Grade
The land around a residence is supposed to have a slight convex shape so that water drains away from a home’s foundation. If the landscaping around a property is done right, then it’s called a positive grade. A negative grade, however, means that the water pools up around your home and is unable to drain elsewhere.
A negative yard grade almost always guarantees some degree of soil washout. While it is true that a positive grade would also result in a bit of soil washout (since the rainwater is flowing on the topsoil regardless of the direction it’s going), water can do more damage when the yard grade is negative. This is because soil absorbs the water that pools up on your property, displacing the lower layers of the soil.
Cracked Concrete Slab
Cracked concrete is a clear sign of soil washout because it indicates that the slab’s foundation is uneven. As the soil washes out and gaps form under the slab, the concrete’s pressure distribution becomes uneven. Concrete has very little tensile strength in comparison to its compression strength. Tensile strength refers to a material’s ability to handle pressure.
When supporting large weights, if the slab can distribute the pressure evenly throughout its body, it will not break. However, if the pressure distributes unevenly, the concrete will begin to crack. An uneven or unstable foundation will not allow the slab to handle the pressure properly. This is why, even before the unevenness, cracks on the concrete indicate a problem with the soil.
Foundation Problems
The concrete slabs outside your home aren’t the only ones in danger when there’s soil washout. Your foundation can also settle if it doesn’t have an even layer of soil to support it. When your foundation settles, the bottom part of your home will begin to sink to one side. This affects the rest of the house’s structure, meaning that there are many problem signs for you to look for if you believe the soil erosion going on around your property is causing structural damage.
Here are some of the signs to look for:
- Wall and ceiling cracks
- Basement or crawl space floods
- Stair-step cracks along mortar
- Jammed doors and windows
- Warped or broken window and door frames
- Tilting chimney
- Uneven floor
- Uneven basement walls
These are just the problem signs you experience when you have a basement or crawl space. With slab foundations, the damage can be a lot more severe. This is because most of your home’s plumbing and HVAC systems are right underneath the slab. If these get damaged due to settling, then it will affect your day-to-day life and you’ll be paying a lot for repairs. Another big problem that comes as a result from slab settling is indoor flooding, so watch out for that as well.
When You Should Worry About Soil Washout
There are certain circumstances that lead to soil washout faster than others. Not all of them will be applicable to you, but there are some that are completely unavoidable and out of your control as a homeowner. Informing yourself of when your soil is most likely to wash out will help you know when you’re supposed to be most vigilant.
When It Storms
Surface runoff isn’t always immediate. For example, in Virginia Beach, VA, the soil (from the Altavista series soil) is slow to wash out despite being fine and sandy. For some soils, it takes a large incline in order to wash out significantly in a short period of time.
However, nothing erodes and displaces soil faster than a storm. In Richmond, VA, hurricanes and tropical storms are what causes the most property damage. Atlantic storm season begins in the summer and usually ends in November. The intense winds and heavy rain erode topsoil incredibly fast.
Unfortunately, because storms are a force of nature, there’s not much you can do as a homeowner. At most, you can plant trees and foliage that serve as cover from the wind and rain and mitigate the damage as much as possible.
Early Spring
Most jump for joy upon seeing the signs of early spring. The temperature will finally get warmer, and you won’t have to shovel around snow. For homeowners who worry about soil washout, early spring might mean trouble.
When snow starts to melt all around your property, all that water must go somewhere. Wherever there’s an incline, the melted snow will run down and wash out the soil. If there are any puddles of snow on even surfaces, then soil will absorb it and erode the layers under the topsoil.
Floods
Much like storms, floods are devastating natural disasters that can completely change the landscape of a property. Unfortunately for states near the Atlantic Ocean, flooding is a frequent occurrence due to tropical storms.
Washington, D.C. doesn’t get a lot of severe hurricanes because most of them lose their strength by the time they reach the area. Despite their weakness, the storm surge produced by these hurricanes raises the water levels of the nearby rivers, which causes flooding. The same thing happens in Roanoke as the remnants of hurricanes drain from Roanoke Valley.
How to Prevent Soil Washout
Soil washout cannot be completely avoided, especially because most of it is caused by the weather. There are, however, certain steps you can take to lessen the amount of erosion the soil of your lawn experiences. After all, mitigating soil erosion is all about limiting your yard’s exposure to water.
Cover
You can protect the soil in your yard by covering it. For your backyard, you can do this by hanging up some shade sails. If you want something that can withstand storms better, then a sturdy, wooden canopy can be built.
You might not be able to do the same for your front yard. Instead of shade, you can cover the soil by planting trees and foliage. This will provide the soil with a bit of cover, but you also need to be careful with the kinds of foliage you plant and how you care for them. Watering them too much will cause you to accidentally wash out the soil where the foliage is, so don’t plant anything that requires a lot of water.
Downspouts
Downspouts should not drain water anywhere near your concrete slabs. You can either extend them or reposition them so that all water flows away from your home.
Pools
It’s completely normal for a pool to lose a few inches of water every year. However, if you think that your in-ground pool is losing too much water, you might have an underground drainage problem. Talk to a professional about repairing your pool’s drainage so that the soil under your pool deck doesn’t wash out.
If you have an above-ground pool, then consider its location. You’ll need to relocate any pool near a concrete slab. If you can’t relocate it to somewhere where there are no slabs around, then make sure to cover the area in a plastic sheet.
Yard Drainage
Talk to your local experts to see what you can do about the drainage around your yard. If there are any improvements to be made, then don’t hesitate to take action.
Keep a close eye on your drainage system and exercise proper maintenance practices. It’s wise to be extra vigilant during the fall (when the wind carries leaves and twigs into drainage systems), during hurricane season (when the rain and water carries debris that can clog up pipes), and during the winter (when discharge pipes can get frozen). You don’t want a clogged-up drain to be the reason why the soil under your concrete erodes.
Yard Grade
With the constant flooding and storms in the Mid-Atlantic states, there’s a lot of soil erosion that changes the landscape of homeowners’ properties. Even if your home’s yard grade was positive when you moved into it, it can change over time. It can help to speak to a landscaping company to assess your yard’s grade every few years and re-grade if needed.
How Can You Fix Settling Concrete?
If the soil on your property is washing out and your concrete slabs are suffering from it, what can you do? Fortunately, JES has the answer in the form of PolyRenewal™ Foam Injections.
PolyRenewal™ is a concrete lifting method that utilizes polyurethane foam. Don’t worry—the polyurethane we use is nothing like the ones used to make sponges. We use closed-cell polyurethane, which is dense, firm, and is capable of withstanding incredible amounts of pressure.
Small holes are drilled into the slab, and the polyurethane foam is injected with a small, handheld machine. Our team will inject enough foam to fill the gap under the slab and lift the concrete. The holes are covered up, and the slab can withstand weight like it normally would after only 15 minutes.
Soil Washout
FAQ's
Besides polyurethane foam injections, there are other methods that involve pumping in different materials in order to lift the slab. These other methods are problematic, and the materials used aren’t as good as polyurethane foam. Many contractors still cling to the old way of doing things despite there being better solutions. That, and many contractors don’t have the tools or training to use a superior method like polyurethane foam injections.
- The Problem with Other Methods
One of the oldest concrete lifting methods is mudjacking. Mudjacking consists of drilling a hole into the slab and pumping in a slurry of cement. Other methods involve the same general procedure, though the material might be different. One of the biggest problems with this method is that it does nothing to stop soil washout, so there’s a chance the slab will settle once more a few years down the line.
Cement is rough and heavy, so the pressure applied to an already weakened layer of soil will only make things worse. Not to mention, cement can crack and break over time, so the material that’s supposed to hold up your slab isn’t reliable. The machines used in mudjacking are also very large, so the job can’t be done in places that are a little more difficult to reach.
- Why Polyurethane Foam Injections Are Better
Polyurethane foam injections have a lot of advantages over methods like mudjacking. First of all, installation is a lot more convenient. The machine used to inject the foam is small, so there are less limitations on where the repairs can be done. With mudjacking, you have to wait one to two days for the cement to cure, so you can’t put weight on the slab for a while. With polyurethane foam injections, everything will be back to normal in no more than 15 minutes.
Polyurethane foam protects the soil from further erosion due to its properties. It’s impermeable, so it acts like a waterproof barrier. It’s also lightweight, so it doesn’t place any pressure on the soil. Unlike cement, polyurethane foam does not erode. It is not affected by the freeze-thaw effect, and it doesn’t shift around, which makes it a long-term solution for concrete slab settling.
Homeowners will sometimes look at a settled slab on their property and panic. They rush to get the slab replaced instead of calling an expert for a concrete lifting repair job. It may not look like it, but concrete lifting can work no matter how severe the settling is. There are some cases in which a slab cannot be lifted, but these are rare.
- When to Replace Your Concrete Slab
Before deciding to replace your settled slab, speak to an experienced concrete lifting professional for proper assessment. Replacing a slab is expensive, tedious, and unnecessary. It’s best to get a professional’s opinion on whether or not it’s too far gone. Part of the reason replacement is so unnecessary is because it doesn’t solve the actual problem: soil washout. If the slab was able to settle once, then it will do so again unless you have a reliable support material like polyurethane foam.
Usually, concrete slabs can be lifted even when they are cracked. The polyurethane foam will still level out the side of the slab that has settled and the two parts can be even again. Once they are leveled, it’s relatively easy to unite them. The only time concrete lifting does not work is if the slab is severely cracked. Polyurethane foam does not work like glue, so it cannot repair a slab with multiple, small cracks.
- How to Avoid Cracking Your Settled Concrete Slab
You’ll want to avoid replacing your slab as much as possible. To make sure that it can be repaired via concrete lifting methods, you need to avoid cracking it. The first thing you need to do is contact your local professionals as soon as you see any signs of concrete settling. Settling gets worse the longer you wait, so taking action early will save you a lot of money.
As you wait for the repairs, avoid putting any weight on the slab. When supported by an uneven base, slabs have a harder time distributing weight evenly. They are more likely to crack when settling, so try your best to limit the amount of weight it has to support. This might mean not walking on your concrete pathways and parking your car other than on your driveway. It may be inconvenient to do for a few days, but it’ll be worth it to avoid cracking your concrete.
Slab foundations are inexpensive and easy to build, making them a popular foundation choice for many. Unfortunately, they are capable of settling just like any of the slabs on your property.
- How Slab Foundations Settle
Slab foundations settle in the same way your driveway or patio slabs settle—due to soil displacement. A negative yard grade and poor yard drainage all contribute to foundation settling, even with slab foundations. The signs are a lot harder to detect, since homeowners can’t observe the damage to their slab foundation in the same way they can their crawl space or basement.
Besides soil washout, a big factor in foundation soil displacement is pressure. Sandy soils are a lot looser and shifty than clay soils, and because they are less dense, displacement is easy when they have to support large weights. As a house is used over the years and heavy furniture is moved about, the foundation has to support more weight. Over time, this does affect the soil.
- How Settled Slab Foundations Are Repaired
Like any slab on your property, you don’t have to replace a slab foundation once it settles. JES can stabilize and even lift your settling slab foundation using slab piers. They are steel rods that transfer the weight of the house to the competent, load-bearing soils below. Because your slab will no longer rely on loose soil, slab foundations will perpetually support your foundation.
PolyRenewal™ can also be used on a slab foundation. Polyurethane foam is able to support over 100 tons of weight, so it’s more than capable of lifting your foundation. Polyurethane foam can’t always be used for slab foundations, and, sometimes, slab piers are required. You would have to talk to your local foundation expert to determine which one you need for your settling slab.
JES Can Fix Your Settling Concrete
If your concrete slabs are settling, then JES can help. Since 1993, we’ve been helping homeowners keep their properties even and stable. We have years of experience in the industry and are able to provide the best repair methods around. We serve Baltimore, MD, Washington, D.C., Charleston, WV, and Virginia (Appomattox, Richmond, Roanoke, Manassas, Virginia Beach).
If you’re interested in PolyRenewal™ for your settling slab, then give us a call or use the online contact form on our website 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.
