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Sinking Sidewalk2026-11-02T15:55:12-06:00

Is Your Sidewalk Sinking? Here's What That Means

A sinking sidewalk is more than an eyesore. Uneven slabs can create trip hazards, allow water to pool and continue to settle over time when the underlying soil isn't stabilized. Without repair, minor height differences often grow into bigger safety concerns as the soil beneath continues to move. Fortunately, most sunken sidewalks can be lifted and leveled without replacement. As part of a free inspection, NV Waterproofing and Foundation Repair determines what's driving the settlement and recommends the best long-term repair.

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Symptoms

Signs Your Sidewalk Needs Attention

Most sidewalks sink slowly over time rather than suddenly. Small changes in the supporting soil beneath the concrete allow slabs to settle over time, creating uneven walking surfaces and larger height differences. Even when settlement looks minor, a professional inspection can identify what's causing the movement, whether it's likely to continue and the best way to restore a safe, level sidewalk.

Unlevel sidewalk sections
Sections settling lower than the neighboring concrete
Trip hazards
Standing water
Growing cracks in the concrete
Slabs separating

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Causes

What Causes a Sidewalk to Sink?

Sidewalks settle when the soil underneath can no longer offer consistent support. In [Target Location] seasonal rainfall, shifting soil moisture and natural ground movement can slowly create voids or weaken the soil beneath the concrete, allowing individual slabs to settle over time. Finding the root cause is the first step toward selecting the right long-term repair.

  • Soil Erosion

    Over time, the soil supporting a sidewalk can slowly wash away, leaving empty spaces beneath the concrete. As those voids grow, sections of the sidewalk lose support, settle unevenly and become more susceptible to cracking.

    Soil erosion often develops below the surface, making it difficult to detect until visible signs of settlement appear. Unless the lost support is restored, the sidewalk can keep sinking as the voids beneath the slab grow.

  • Poorly Compacted Fill Soil

    Many sidewalks are installed over fill soil that’s supposed to be compacted before the pour. If that soil wasn’t compacted properly, it can settle over time, causing the sidewalk above to sink.

    Settlement caused by poorly compacted fill often appears gradually across several years. As the soil compresses under its own weight and everyday foot traffic, the concrete loses uniform support and uneven sections begin to appear.

  • Water Washing Away Supporting Soil

    Water is one of the biggest causes of sidewalk settlement because it can wash supporting soil out from beneath the concrete. Even small amounts of repeated water intrusion can slowly weaken the ground underneath.

    Poor drainage, overflowing gutters, leaking irrigation systems, downspouts and runoff from nearby landscaping can all contribute to soil washout. Correcting these drainage issues along with concrete lifting helps reduce the risk of future settlement.

  • Expansive Soils

    Some soil types naturally expand with moisture and shrink as they dry out. These repeated cycles can shift the ground beneath a sidewalk and cause uneven settlement.

    Where expansive clay soils are common, seasonal moisture changes place ongoing stress on the concrete. Over time, that movement can produce cracks, uneven slabs and trip hazards as parts of the sidewalk settle differently than others.

  • Freeze-Thaw Cycles

    Ongoing freeze and thaw cycles can gradually weaken the soil that supports a sidewalk. As moisture freezes, expands and thaws, the ground shifts beneath the concrete.

    In regions with cold winters, these seasonal cycles can contribute to settlement by creating small voids and allowing soil to move over time. Paired with drainage issues or weak soils, freeze-thaw cycles can speed up sidewalk sinking.

  • Heavy Loads Over Time

    Although sidewalks are designed for foot traffic, repeated heavy loads can place additional stress on the supporting soil. Should the soil already be weak or unstable, it can compress and allow the concrete to sink.

    Heavy equipment, dumpsters, utility vehicles or construction machinery crossing a sidewalk can accelerate settlement. Heavy loads on their own don’t typically cause sinking, though they can make existing soil problems worse and contribute to uneven concrete.

Why a Sinking Sidewalk Shouldn't Wait

  • Stage 1

    Small Height Differences

    One slab settles just a bit lower than the one beside it, creating an uneven walking surface. At this point, homeowners may notice a small trip hazard, puddles after rain or a walkway that no longer looks level.

  • Stage 2

    Continued Settlement

    As the supporting soil continues to shift or wash away, the height difference becomes more noticeable. Trip hazards worsen, cracks may spread and nearby sidewalk slabs can begin settling as the underlying support gives way. Uneven sidewalks can also make travel harder with strollers, wheelchairs and other mobility aids.

  • Stage 3

    More Extensive Damage

    Left unrepaired, settlement can continue until the concrete starts cracking, breaking apart or becomes too damaged to lift effectively. Catching the problem early often allows the sidewalk to be repaired instead of replaced, saving both time and money.

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How NV Waterproofing and Foundation Repair Repairs Sinking Sidewalks

For a sinking sidewalk in [Target Location], repairing the soil underneath is often a more effective long-term fix than replacing the concrete alone. NV Waterproofing and Foundation Repair raises and levels settled sidewalk slabs with PolyLevel®, restoring a safer, more even walking surface. To help protect the repair, NexusPro® Joint Sealant seals joints and cracks to reduce water intrusion that can contribute to future soil erosion and settlement.

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  • PolyLevel® Concrete Lifting

    PolyLevel® is injected under settled sidewalk slabs, where it expands to fill voids, stabilize weak soils and gently raise the concrete back toward its original position. The lightweight foam sets quickly, so most sidewalks are back to normal foot traffic the same day.

  • NexusPro® Joint Sealant

    Water is a leading contributor to sidewalk settlement. Once the sidewalk is lifted, NexusPro® can seal joints and cracks to help keep water away from the supporting soil below. By helping reduce soil erosion and washout, it protects the repair and supports long-term performance.

How It Works

NV Waterproofing and Foundation Repair's Process for Permanently Lifting and Stabilizing Sinking Sidewalks

Step 1

Schedule Your Free Sidewalk Inspection

Each sidewalk repair begins with a complete inspection. A System Design Specialist examines the condition of the concrete, determines what caused the settlement and decides whether concrete lifting is the right solution. You’ll receive a straightforward explanation of the findings along with a customized repair plan that targets the underlying cause—not just the visible symptoms.

Step 2

Prepare the Concrete

Once the repair plan is set, the affected sidewalk sections are prepared for lifting. Small, penny-sized holes are carefully drilled into the concrete, creating access points for the PolyLevel® material while preserving the sidewalk’s appearance.

Step 3

Raise and Stabilize the Sidewalk

PolyLevel® expanding polyurethane foam is pumped beneath the sidewalk, where it spreads into empty spaces, fills voids and stabilizes the supporting soil. As the material expands, it gently raises settled slabs toward a safer, more level position while helping restore support beneath the concrete.

Step 4

Patch and Seal the Repair

After the sidewalk has been lifted and stabilized, the injection holes are patched to blend with the surrounding concrete. Cracks and joints are then treated with NexusPro® Joint Sealant to help reduce water infiltration and keep the supporting soil from washing out later.

Step 5

Add Long-Term Protection

To help extend the life of the repair, SealantPro® is applied to shield the concrete surface from moisture, chemicals and everyday wear. NexusPro® Joint Sealant also works to reduce water infiltration that can cause future soil washout under the sidewalk. Combined, these systems lift, seal and protect your concrete for long-lasting performance.

Benefits

Why Homeowners Trust NV Waterproofing and Foundation Repair

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Don't just take our word for it

See what our customers have to say about our work.

NV Waterproofing was extremely responsive and 100% committed to identifying our water problem and designing a solution. Their work was excellent. The crew was on time and organized. They were very careful to protect the exterior landscaping and the interior of our home from dirt and debris. Even two years later, they responded to a sump problem at no additional charge. NV Waterproofing does the job right and stands behind its work.

Mike and Lynn F. | Columbia, MD

We bought a house in a state of disrepair, and so we've had to work with a number of contractors. I'd rank this company at the top of the list for their professionalism, knowledge, experience, and honesty. We had bowing of our basement walls that needed to be addressed. Michael came out to assess the situation, and gave us some options. After speaking with him, I felt very confident in their ability to buttress our walls. It was also a huge bonus that we were able to set up a payment plan for this job too. When the team showed up, Casey, Kevin, and Grant, they were super polite and professional. They took great care of our property, and if they had a question about anything, they asked. Also, if I had a question, Casey (the foreman), was very knowledgeable and quick to answer. They presented the work as they progressed through the job, and really, I was actually a little blown away by the scale of the project, and the speed at which they worked. What an impressive job they did! We're very confident in the work they did and will hire them again.

Ellen M.  | Takoma Park, MD

We were referred to NV Waterproofing from my brother-in-law who used them and was pleased. They came out and gave us an estimate - they were very prompt. We had the work done - it looked great and I am sure will do the job (only time will tell). We did have a miscommunication with the work (mostly on our part), but the owner had it fixed promptly and without additional cost. I would highly recommend them to anyone with water issues in their basement.

Susan C. | Washington DC, DC

NV stuck with me and made sure I was happy. Roberto Jr kept me calm as my problem persisted and kept working on a solution beyond the obvious. I highly recommend. Looking forward to a dry basement this summer.

Dean R. | Washington, DC

I am writing this letter to commend members of your organization for the waterproofing work performed on and around the foundation of my house. Despite situations beyond the control of both me and your associate, he always maintained professionalism and demonstrated why he is an outstanding representative of your organization. The crew obviously knew what had to be done and went about doing it. They were prompt in arriving at work each day, diligent in the performance of their duties (in spite of high heat and humidity), and took measures to ensure the safety around the excavated area (important because of children in the neighborhood). Unlike other construction sites I have seen, the crew maintained the area free of litter— no small measure these days! In addition, the crew always provided clear explanations of the work to be done each day, answering the questions with forthright and clear responses, never hurrying the discussion. As I was not on site while work was being done, they called me several times, taking those extra steps to keep me informed of the status of the work and aware of the tasks yet to be performed— something that is greatly appreciated. I would appreciate it if you would offer my heartfelt thanks to your able crew for the quality waterproofing work performed and the excellent communication and coordination exhibited by them.

Myra L. | Washington, DC

In my 12 years of having NV Waterproofing as a business partner, they have always proved reliable and trustworthy. They are a great value for me and my customers.

Darryl O. of Brookfield Homes, | Washington, DC

Great professional service and able to respond in timely manner to the project need.

Blake B. | Washington, DC

Brendan was very knowledgeable, professional and courteous. Highly recommend.

Cesar T. | Arlington, VA

A brief note to thank NV Waterproofing for extreme professionalism and courtesy in the manner in which my recent basement water seepage problem was addressed. From the initial contact with Jim, through the work with Roberto, Carlos and Jose, it was an overall pleasant experience – not to mention my contact with the owner and his responsiveness.

Ramesh T. | Arlington, VA

These guys were amazing. The initial visit was smooth, not pushy at all and he was even able to accommodate the relocation of a small drainage pipe. The demo to install the system was done beautifully, yes it was really good, you can tell they were precise and careful when doing so. Everything was clean, no stains on my carpet and they protected everything. No leak so far and I love it. Did I mention the price was excellent? I had 3 other companies to estimate thousands and even tried to sell extra unnecessary equipment. Thank you NV Waterproofing I have and will continue to recommend you.

Chelly Z. | Falls Church, VA

We appreciated NV Waterproofing's honesty and the men who worked tirelessly in uncomfortably cold weather. We've had one big storm since they finished and the basement walls are nice and dry. Nice work!

Peter V. | Falls Church, VA

Mauricio and Cristian were the initial sales reps who came to examine the issue and they took the time to test drainage that might have potentially been creating the water issue. They offered a reasonable solution (sealing the visible cracks and holes in the concrete) and I was contacted within a couple of days with an estimate and scheduling options. Sean was our tech and he did a fantastic job diagnosing the issue beyond just the cracks. He not only address all the holes and cracks in the concrete and mortar, he sealed up additional entry points above the foundation. He sourced additional materials to cover openings for cable lines. He went above and beyond and gave us measured information on how we should continue to monitor and treat this area as the house settles. He was thorough, informative, and provided excellent service in his work. I'm very glad that Sean was the technician sent to us and I would specifically request him for your projects.

Sara T. | Falls Church, VA

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Before & after photos

Check out before and after photos from some of our completed projects.

  • Sunken Concrete Step Repair in Stephens City, VA

    This Stephens City, VA homeowner was dealing with a sunken concrete front step that had settled over time, creating an uneven entryway and a noticeable tripping hazard near the front door. Sunken concrete steps can make everyday foot traffic unsafe for homeowners, guests, and delivery drivers, while also taking away from the home’s curb appeal. Our concrete repair team lifted and leveled the front step back to its proper position, creating a safer, more stable walkway and entrance. This concrete step repair helped reduce the risk of falls, improved the look of the front entry, and gave the home a cleaner, more welcoming appearance. The homeowner was thrilled with the outcome — a big transformation that improved both safety and curb appeal!

  • Basement Waterproofing in Winchestor, VA

    A homeowner in Winchester, VA, was struggling with a failing sump pump that couldn’t keep up during heavy rainstorms, leaving their basement vulnerable to water intrusion. The lack of a reliable backup system also left them worried about potential flooding during power outages. Frustrated and seeking a dependable solution, they contacted NV Waterproofing and Foundation Repair, a trusted basement waterproofing company in Winchester, VA.

    After assessing the situation, we replaced their old sump pump with a state-of-the-art TripleSafe Sump Pump system. This advanced system includes three levels of protection: a primary pump, a secondary pump for heavy water flow, and a battery backup to ensure the basement stays dry even during power outages. The homeowner now has peace of mind knowing their basement is fully protected, no matter the weather.

  • Pool Deck Leveling in Manassas, VA

    A homeowner in Manassas, VA, quickly realized their dream backyard pool was at risk when the surrounding concrete pool deck began to show serious problems. Uneven and sunken slabs created tripping hazards and unsightly cracks, making both safety and aesthetics a challenge for anyone using the space. Additionally, water from rain and pool use was pooling in low spots, causing slippery surfaces and further soil erosion beneath the deck. These issues not only threatened the safety of family and guests but also compromised the value and enjoyment of the home.

    Seeking an effective solution, the homeowner reached out to our team for a professional assessment. We identified the main cause of settlement: soil erosion under the slabs—a common issue in Manassas due to its clay-rich ground and fluctuating moisture. To address both the immediate hazards and prevent future damage, we recommended our two-part approach: the cutting-edge PolyLevel® concrete leveling system and NexusPro® Joint Sealant.

    The repair process began with drilling small holes into the affected concrete slabs, allowing us to inject high-strength PolyLevel® polyurethane foam beneath the surface. As the foam expanded, it filled voids, stabilized the soil, and gently lifted the slabs back to their original positions. The process was quick, clean, and minimized disruption, giving the pool deck a level, safe surface once again. PolyLevel® foam is waterproof and lightweight, reducing the risk of future settling and ensuring long-term durability, even in a wet poolside environment.

    To provide further protection, we sealed all cracks and joints with NexusPro® Joint Sealant. This flexible, weather-resistant sealant prevents water from seeping beneath the slabs, protecting the soil and concrete from additional erosion. The result was a clean, finished appearance that not only improved the look of the deck but also safeguarded it for years to come.

    Thanks to modern concrete leveling technology, the homeowner’s pool deck was transformed from a liability into a safe and attractive outdoor gathering space. The project was completed in a single day, with minimal mess and immediate results, giving the homeowner peace of mind and renewed pride in their backyard. If you’re facing similar issues with your pool deck in Manassas, VA, the PolyLevel® system and NexusPro® Joint Sealant offer a fast, effective, and lasting

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Frequently Asked Questions

How much does sinking sidewalk repair cost? 2026-10-02T12:41:33-05:00

What it costs to repair a sinking sidewalk depends on the extent of settlement, the number of affected slabs, accessibility and whether additional repairs are recommended for drainage or other underlying issues. Often, concrete lifting is more affordable than replacement since it restores the existing sidewalk without demolition or drawn-out construction. A free inspection is the best way to determine the most cost-effective repair for your specific situation. 

How long does sidewalk lifting last? 2026-10-02T12:41:06-05:00

When the underlying cause of settlement is properly corrected, PolyLevel® delivers a long-lasting repair designed to support the sidewalk for years to come. How it performs depends on soil conditions, drainage and the overall condition of the concrete. During your inspection, NV Waterproofing and Foundation Repair will evaluate these factors and recommend the most effective repair for lasting results.

Is a sinking sidewalk dangerous? 2026-10-02T12:40:39-05:00

Yes, and often more than people expect. Even a slight height difference between sidewalk slabs can create a trip hazard for family members, guests, neighbors and delivery drivers. Homeowners are often surprised how little settlement it takes to create an unsafe walking surface. Uneven walkways may also be more difficult to navigate with strollers, wheelchairs or other mobility aids. Since settlement usually worsens over time, addressing the problem early helps improve safety and may prevent more extensive repairs later. 

Can a sinking sidewalk be repaired without replacing it? 2026-10-02T12:40:03-05:00

In most cases, yes. When the concrete is still structurally sound, PolyLevel® can lift and level settled sidewalk slabs without the cost and disruption of replacement. Expanding polyurethane foam is pumped beneath the concrete, filling voids, stabilizing the underlying soil and raising the sidewalk toward its original position. A professional inspection can determine whether lifting or replacement is the best long-term solution. 

What causes a sidewalk to sink? 2026-10-02T12:38:51-05:00

Sidewalks generally sink once the soil under the concrete can no longer offer consistent support. Poorly compacted fill, natural soil settlement, soil erosion, water washing away support, freeze-thaw cycles and expansive clay soils can all open voids or cause the ground to shift. Once support beneath the slab weakens, portions of the sidewalk gradually settle and become uneven. 

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