Undermining or Tidal Seawall Washout

Q: After a strong tide, I noticed the ground behind my seawall suddenly dropped — does that mean the soil is washing out?

Yes, that’s a classic sign of tidal washout. The shifting tides have likely pulled soil from beneath your wall, leaving hidden voids. LUX fixes this permanently by using polyurethane grout injection , where expanding marine-grade resin is injected into the voids to stabilize the ground, compact loose soil, and seal any small leaks. Once set, it creates a watertight, erosion-resistant layer that protects your seawall from further washout — without excavation or costly replacement.

Q: After a storm, the ground behind my seawall in Jacksonville, FL, feels soft — is that a sign of tidal washout?

Yes. Soft or sinking soil after a storm usually means tidal water has carried soil out from beneath the wall. LUX Foundation Solutions inspects your seawall and uses polyurethane grout injection to fill underground voids, compact the soil, and stop washout before it worsens.

Q: My seawall in St. Augustine, FL, has small holes forming near the base — should I be worried?

Those small holes are often early signs of undermining, where tidal water is eroding the soil from underneath. Our team repairs this using polyurethane grout injection , which fills those voids and stabilizes the structure — preventing further erosion and shoreline collapse.

Q: What causes soil to disappear behind seawalls in Palm Coast, FL?

In Palm Coast, frequent tidal changes and sandy coastal soil make seawalls prone to washout. Water slipping through cracks or joints gradually removes soil. LUX repairs this by injecting expanding polyurethane foam behind the wall, creating a watertight, compact base that resists future soil movement.

Q: How do I know if tidal washout is affecting my seawall in Florida?

If you notice small depressions, water pooling, or gaps between your yard and seawall, tidal washout has likely begun. LUX Foundation Solutions performs detailed inspections using moisture detection and pressure testing to confirm the problem, then restores stability with long-lasting polyurethane soil stabilization.

Q: What happens if I ignore signs of seawall undermining or tidal washout?

Ignoring early signs like soft soil, gaps, or sinking ground behind your seawall can lead to serious structural failure. Over time, continued washout removes the wall’s foundation support, causing cracks, leaning, or collapse. LUX Foundation Solutions prevents this with polyurethane grout injection , which fills voids, stabilizes soil, and restores strength before costly damage occurs.

Restore strength beneath your seawall — stop Florida tidal washout fast.

Tidal washout happens when waves and tides erode the soil supporting your seawall, leaving hidden voids beneath it. In Florida’s coastal zones, this leads to settling, cracks, and collapse. Learn how LUX stops seawall undermining before permanent damage occurs.

What is Undermining or Tidal Seawall Washout?

Undermining or tidal seawall washout happens when powerful tides, waves, or groundwater movement wash away the soil supporting your seawall. As this backfill erodes, voids form behind the wall, weakening its foundation and causing cracks, leaning, or even collapse.

In Florida’s coastal environment, sandy soils and frequent storms make tidal washout especially destructive. Water seeps through joints or under the seawall, carrying sediment out with each tide. Over time, this hidden erosion compromises stability and threatens your property’s shoreline.

LUX Foundation Solutions identifies and repairs seawall undermining using advanced polyurethane grout injection— a proven method that fills voids, stabilizes soil, and restores structural support to protect your Florida waterfront from ongoing washout damage.

Schedule a free estimate

Signs of Undermining or Tidal Seawall Washout in Florida

Undermining or tidal seawall washout often start below the surface, showing subtle signs before major damage occurs. In Florida’s sandy coastal regions, soil erosion from tides and waves can rapidly weaken your seawall foundation. Watch for these early warning signs:

Sinkholes or depressions forming behind the seawall — proof of soil loss and hidden voids.
Gaps between seawall panels or the cap, showing uneven settlement.
Cracks or separation along the base where water escapes through eroded soil.
Leaning or bulging sections caused by lost backfill support.
Standing water or saturated soil near the seawall after high tide or rainfall.
Pitted or hollow-sounding concrete, a sign of internal washout.

If you notice any of these symptoms, LUX Foundation Solutions offers free seawall assessments across Florida to locate washout areas and restore your wall’s strength before failure occurs.

Sinkholes or Depressions

Gaps Between Seawall Panels

Cracks or Separation Along the Base

Leaning or Bulging Wall Sections

Standing Water or Saturated Soil

Pitted or Hollow-Sounding Concrete

What Causes Undermining or Tidal Seawall Washout in Florida?

Florida’s coastal environment constantly subjects seawalls to water movement, pressure, and soil displacement. Over time, these forces create voids beneath or behind the wall — known as undermining or tidal washout.

Below are the three most common causes Florida homeowners should watch for:

Constant Tidal Pressure and Wave Impact

Florida’s strong tidal fluctuations and storm surges force water under and behind seawalls. As the tide recedes, soil is pulled out through small openings, creating washout cavities and uneven settlement — a primary cause of undermining in coastal seawalls.

Water Escaping Through Cracks, Joints, or Seams

When seawall panels, joints, or caps crack, tidal water seeps in and out with every rise and fall of the tide. This constant water movement carries fine soil particles away from behind or beneath the seawall — gradually forming voids that destabilize the wall.

Poorly Compacted or Eroded Backfill Soil

If the backfill behind a seawall wasn’t compacted properly during construction or has degraded over time, it becomes vulnerable to movement. This loose soil easily washes away during heavy rainfall or high tides, leading to voids and sinkholes near the seawall base.

Our Proven Undermining & Tidal Seawall Washout Repair Solution

Undermining or tidal washout weakens your seawall from below, creating hidden voids and unstable soil that threaten your property’s shoreline. At LUX Foundation Solutions, we restore seawall stability using polyurethane grout injection — a precise, long-lasting solution designed for Florida’s coastal conditions.

Polyurethane Grout Injection

After a strong tide, I noticed the ground behind my seawall suddenly dropped — does that mean the soil is washing out?

Yes, that’s a classic sign of tidal washout. The shifting tides have likely pulled soil from beneath your wall, leaving hidden voids. LUX fixes this permanently by using polyurethane grout injection, where expanding marine-grade resin is injected into the voids to stabilize the ground, compact loose soil, and seal any small leaks. Once set, it creates a watertight, erosion-resistant layer that protects your seawall from further washout — without excavation or costly replacement.

View more Seawall Repair Solutions

Schedule Your Free Seawall Washout Repair Assessment Today

Don’t wait until a small void turns into a collapsed seawall. Tidal washout and undermining can spread quickly under Florida’s shifting coastal soils — threatening your property’s stability and shoreline.

LUX Foundation Solutions offers free, no-obligation seawall assessments to detect hidden voids, washout areas, and soil loss before major damage occurs. Using Polyurethane Grout Injection, our experts fill gaps, compact loose soil, and reinforce your seawall for long-term protection against erosion and tidal pressure.

Serving Jacksonville, St. Augustine, Palm Coast, Gainesville, Ocala, and coastal areas across Northern Florida.

Call 904-921-3589 to schedule your free seawall inspection today.

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Undermining or Tidal Seawall Washout FAQs

After a storm, the ground behind my seawall in Jacksonville, FL, feels soft — is that a sign of tidal washout?

Yes. Soft or sinking soil after a storm usually means tidal water has carried soil out from beneath the wall. LUX Foundation Solutions inspects your seawall and uses polyurethane grout injection to fill underground voids, compact the soil, and stop washout before it worsens.

My seawall in St. Augustine, FL, has small holes forming near the base — should I be worried?

Those small holes are often early signs of undermining, where tidal water is eroding the soil from underneath. Our team repairs this using polyurethane grout injection, which fills those voids and stabilizes the structure — preventing further erosion and shoreline collapse.

What causes soil to disappear behind seawalls in Palm Coast, FL?

In Palm Coast, frequent tidal changes and sandy coastal soil make seawalls prone to washout. Water slipping through cracks or joints gradually removes soil. LUX repairs this by injecting expanding polyurethane foam behind the wall, creating a watertight, compact base that resists future soil movement.

How do I know if tidal washout is affecting my seawall in Florida?

If you notice small depressions, water pooling, or gaps between your yard and seawall, tidal washout has likely begun. LUX Foundation Solutions performs detailed inspections using moisture detection and pressure testing to confirm the problem, then restores stability with long-lasting polyurethane soil stabilization.

What happens if I ignore signs of seawall undermining or tidal washout?

Ignoring early signs like soft soil, gaps, or sinking ground behind your seawall can lead to serious structural failure. Over time, continued washout removes the wall’s foundation support, causing cracks, leaning, or collapse. LUX Foundation Solutions prevents this with polyurethane grout injection, which fills voids, stabilizes soil, and restores strength before costly damage occurs.