Slab Leaks or Soil Washout? How to Diagnose a Sinking Floor in Florida

Why Florida slabs sink after storms

A slab that suddenly feels soft underfoot or a floor that goes out of level after a heavy rain is more than a nuisance. In Florida, water moves fast across flat terrain and sandy soils, and when it finds a path under a home it can either leak from a pressurized pipe or wash out the bearing soil that supports the concrete.

Both problems look similar on the surface, yet the fixes are very different. Choosing the right path starts with a simple diagnosis you can do at home, followed by a professional inspection that confirms the cause and maps a repair that actually lasts.

When you are ready for a clear plan, APD Foundation Repair can evaluate the slab, trace the water source, and stabilize the structure so it stays put through the next storm season.

What a slab leak really is

A slab leak is pressurized water escaping from a supply line or hot-water loop that runs beneath or through the concrete. The leak is continuous until the line is shut off or repaired. Because the water is under pressure, it tends to spread sideways along the path of least resistance, warming the concrete if it is a hot line and keeping the underside of the slab damp even when the weather is dry.

As the moisture wicks up, the top of the concrete can release salts, adhesives can fail, and wood or laminate flooring can buckle. If the leak runs long enough, it may wash fine particles away and create a small void, but the primary issue is ongoing water, not a change in the broader soil support. Fixing this problem focuses on the plumbing and on drying the slab.

If the leak has caused visible settlement, the structure may also need Concrete Repair to restore support.

What soil washout really is

Soil washout is different. It is driven by rainfall, roof runoff, pool overflow, broken gutter leaders, irrigation overspray, or poor grading that sends water under the slab.

The water is not pressurized by a pipe. Instead, it carries away sand or fines, leaves a void, and reduces the contact between concrete and ground. Once contact is lost, the slab flexes under load and cracks. Symptoms tend to flare after storms and then stabilize in dry weather.

The cure is not a plumber. The cure is stopping the water routes and rebuilding support under the slab. That often means surface water fixes, subsurface drainage, and targeted stabilization with Concrete Leveling where voids formed. If your site shows erosion channels or roof drip lines that dig trenches beside the house, Drainage Solutions will be part of the plan.

Early signs that point to a slab leak

Homes with slab leaks commonly show warm spots in flooring, higher water bills, or the sound of water movement when no fixtures are running. Tile grout can discolor in a single area, and moisture meters will spike over one room while other rooms remain dry. If you shut the main water valve and the meter stops spinning, then open the valve and the meter begins to spin again while every faucet is off, that is a strong indicator of a pressurized leak.

If you experience several of these signs, call a licensed leak detection specialist first to trace the exact run. After the pipe is located and repaired, Foundation Waterproofing can help dry the slab and protect against the moisture cycle that weakens adhesives and finishes.

Early signs that point to soil washout

Washout behaves more like weather. Floors feel solid in dry periods, then a thunderstorm arrives and you notice a new hollow sound along a doorway or a dip in a hallway that was flat last week. Hairline cracks widen after big rains, then stop moving.

Gaps open between the slab edge and the soil outside. Ants begin to travel along a new seam where the slab meets the wall because an underground void gave them easy passage. Cupping or heaving may appear at control joints after a downpour. If you tap the slab with a rubber mallet and hear a drumlike echo in a broad area, you likely have air beneath the concrete.

Soil washout calls for a site review that looks at grading, downspouts, driveway edges, pool deck overflows, and nearby hardscape. A comprehensive fix almost always includes Drainage Solutions and targeted Concrete Leveling to fill voids and re-establish uniform support.

Simple checks you can do today

You do not need special tools to gather useful clues. Start by checking your water meter when all fixtures are off. If the low-flow indicator moves, shut the main valve at the house and see if the indicator stops. A hot spot on tile that stays warm for hours is another clue, especially in a home with a recirculating hot-water loop.

Next, walk the outside after a storm. Look for soil that has slumped away from the slab, mulch washed into low points, or splash marks on the stem wall. Peeling paint along the base of exterior walls often signals persistent splashback.

While you are outside, confirm that downspouts extend beyond planting beds and that the ground slopes away from the house.

If you see telltale signs of erosion or standing water near the foundation, note those areas for correction with Drainage Solutions and Retaining Wall Addition where grade control is needed.

How professionals confirm the source

A complete diagnosis blends plumbing tests and structural evaluation. For suspected slab leaks, a licensed contractor uses acoustic listening, pressure tests, and thermal imaging to pinpoint the break. Once the leak is isolated, the line is repaired or rerouted.

Afterward, the slab must dry and any softened flooring adhesives need replacement. For suspected washout, a foundation specialist performs elevation readings, probes for voids, and evaluates drainage. If settlement is localized under a load path or near a concentrated stormwater outlet, the plan may include compaction grouting or lightweight polyurethane injection along with surface fixes.

When movement reflects a deeper loss of bearing, selective underpinning with Helical Piers may be recommended to transfer loads into stable soils. If moisture has worked into living spaces, Crawl Space Solutions and targeted Foundation Waterproofing help restore a dry interior.

Repairs that work for slab leaks

When a pressurized line is the culprit, solving the leak is the first step. Many Florida homes benefit from rerouting hot-water lines out of the slab to the attic or walls so future failures are easier to access.

After plumbing work, concrete patches must be tied properly to the original slab with dowels and bonding agents, and finishes must be replaced with the right adhesives for a previously wet surface.

If the leak caused minor settlement or hollow spots, a controlled fill beneath the slab restores support without removing finished floors. That is where Concrete Leveling is valuable. The injection material flows into voids, cures quickly, and limits the chance that new tile or plank edges will crack months later. Where water has migrated into walls, Foundation Repair addresses any resulting cracks and ties the structural fix to moisture control so the same stress does not return.

Repairs that work for soil washout

Soil washout responds to water management first, then stabilization. Grading is tuned so the first ten feet from the house shed water.

Roof runoff is captured and carried away with downspout extensions, catch basins, and buried piping tailored to sandy soils. Concrete joints and edges that once funneled water under the slab are sealed or re-detailed. If your pool deck or patio has settled, re-establishing uniform support is essential so the concrete stops flexing and cracking.

On flatwork and interior slabs, Concrete Leveling fills voids and can lift surfaces back into plane. Around homes that sit near slopes, a small Retaining Wall Addition may hold back migrating soils and give drainage a controlled path.

If stormwater keeps the foundation damp, exterior Foundation Waterproofing and interior drying measures in adjacent crawl spaces create a system that stays dry through seasonal rains.

When cracks mean more than cosmetic damage

Cracks are the language concrete uses to tell you what happened. Hairline shrinkage is normal and often harmless. A single diagonal crack that widens in wet weather then pauses in dry weather points toward soil response. Network cracks around a warm area and persistent moisture inside the home lean toward a leak.

Stair-step cracking in block stem walls and binding doors or windows point to differential settlement. If the crack pattern threatens structure or the movement keeps growing, a deeper fix is needed.

Foundation specialists evaluate whether to add bearing using Helical Piers, stabilize soils that were undercut by water, or stitch and brace specific elements. For exterior separation and vertical splits, see our guide on Wall Cracks.

For interior symptoms like tile breaks and ridges that show up in the living areas, our Floor Cracks resource can help you read the signs and decide next steps.

Pools, patios, and driveways that drop after storms

Hardscape tells the water story better than drywall ever could. If a pool deck settles at the beam after a summer downpour, it is rarely a plumbing leak. The backfill next to the pool likely loosened and washed toward a low point.

The same logic applies to patios and driveway slabs that tilt toward a downspout. Fixes begin with redirecting runoff and sealing joints that acted like channels. Then voids are filled and panels are brought back to grade with Concrete Leveling.

If cracking has spread across a patio, targeted patching and joint redesign may be smarter than full replacement. Our Cracked Concrete Patio Repair page shows how we stabilize the base before we address the surface so the repair remains tight through the next rainy season.

Coastal lots, sea walls, and settlement near the water

Homes along canals and bays face unique hydraulic forces. Boat traffic, king tides, and storm surges move water under and around structures.

If a deck or slab near the shoreline starts to drop, the soil may be migrating toward the water. The solution mixes drainage, soil retention, and in some cases shoreline fixes. Where a failing cap or joint is letting soil escape, Sea Wall Repair helps stop the loss. Once the edge holds, we rebuild support behind the wall and tune site drainage so ordinary rains do not refill the same path. For driveways and walks near the water, finish the system with Drainage Solutions that keep fresh water from chasing the tide through your yard.

Costs, timelines, and what to expect

Slab leaks vary widely because access drives price. A simple reroute above the slab can be completed in a day or two, with drying and finish replacement scheduled right after. Soil washout repairs depend on the size of the voids and how much drainage work is required. Many projects blend a day of water-routing fixes with a day of Concrete Leveling, allowing you to get back to normal quickly.

Structural settlement that calls for Helical Piers takes longer because each pier is load-tested as it goes.

Throughout, our goal is to keep living areas usable and to sequence work so the messy steps come first and do not undo the finishing steps. We provide clear proposals, daily communication, and a cleanup that leaves your property tidy.

How to prevent a repeat

Prevention is simple and powerful. Keep water away from the foundation with clean gutters, long downspout extensions, and grading that sheds water.

Seal joints along driveways, garage slabs, and pool decks so storms do not funnel water under your concrete. If your property sits low, capture runoff with Drainage Solutions and carry it to daylight. If you had a slab leak, consider rerouting vulnerable lines so a future repair does not require cutting the slab again.

Schedule a quick look each spring to verify that soil still meets the slab evenly and that no new paths have formed. When you see early signs, ask APD Foundation Repair for a site review. Small corrections now are far less expensive than structural fixes later.

When to call and who to call first

If your meter is spinning and floors feel warm, call a leak detection specialist to confirm the plumbing failure. After the pipe is repaired, we can stabilize the slab, restore bearing where needed, and waterproof the affected areas with Foundation Waterproofing.

If symptoms rise and fall with the weather or you can see erosion near the house, call us first for a foundation and drainage evaluation. We will map water routes, design a fix that matches Florida soils, and bring the slab back to a stable, dry state.

If your neighborhood sits in known sinkhole territory and the symptoms include broad settlement or circular depressions, our Sinkhole Repair team can investigate deeper geotechnical causes and protect your investment.

The bottom line

Slab leaks and soil washout can look alike at first glance, but their fingerprints are different. Leaks leave warm floors, rising water bills, and persistent moisture in one zone. Washout follows the weather, leaves voids that echo when tapped, and shows up outside as slumped soil or trenches at drip lines.

The fixes only work when they match the cause. That is why a short, careful diagnosis is worth the time. Whether your home needs plumbing reroutes and drying, or site drainage, leveling, and selective underpinning, APD Foundation Repair delivers a plan that stops movement and keeps it from coming back. Reach out, and let us help you protect your Florida home with the right repair the first time.