Interior slab settled? Epp lifts the floor without tearing it out.

A sloped interior floor. A basement slab that has dropped at one corner, a slab-on-grade living room with a noticeable dip, a garage floor that runs downhill to a single low point. Is almost always a soil problem under the slab rather than a slab problem itself. Epp Foundation Repair has been doing concrete leveling on interior slabs across Nebraska, Iowa, Kansas, and Missouri since 1994, and most interior slab calls turn out to be liftable rather than candidates for replacement. The settlement looks alarming because it shows up inside the house where homeowners walk on it every day, but the underlying mechanism is the same as any other settled slab. A void has opened below it. Epp Foundation Repair starts every interior slab call with elevation mapping. The inspector arrives with a digital level or laser, sets a reference point at what appears to be the highest stable corner, and reads elevation in a grid across the floor at 4- to 6-foot intervals. That map tells us where the slab has dropped, how much, and in what pattern. A perimeter drop points to backfill consolidation outside the foundation pulling the slab edge down. A center drop usually means a plumbing leak created a void, or the original sub-slab fill was poorly compacted. Local depressions usually mean a discrete void from a buried organic, a collapsed sewer line, or expansive clay heave reversing.

A concrete slab has almost no flexural strength relative to its dead load. The slab is rigid enough to span small voids, but once the unsupported area exceeds roughly 3 to 4 feet, the slab cracks and drops into the void. By the time a homeowner notices a sloped floor, the void below is usually larger than the visible cracking suggests. The repair has to fill the void and re-support the slab. Not just lift the visible part. In Nebraska and western Iowa, the most common cause of interior slab settlement we see in 1960s through 1990s slab-on-grade ranch homes is hydroconsolidation of the loess fill placed below the slab during original construction. Slab-on-grade homes in this region routinely used on-site loess or fine sand as sub-slab fill, placed in 12- to 24-inch lifts without proper compaction. Over 20 to 50 years that fill slowly densifies, especially after a saturating event like a slab plumbing leak or a wet basement year, and the slab drops 1 to 3 inches. In basements, the settlement signature is different. Usually a corner drop where the backfill against the foundation wall consolidated and pulled the slab edge with it. In the Kansas-Missouri clay belt the dominant interior slab problem is plumbing-leak-driven clay heave at the center of the slab, followed years later by the same clay drying and contracting, leaving a void. Clays with plasticity index above 30 swell 15% volumetrically when wet and shrink the same amount when dry, and that 15% swing happens inside the house if a slab plumbing line has been leaking quietly under the floor.

Five conditions Epp checks inside the house before quoting an interior lift

1. Active plumbing leaks. A pressure test on the slab plumbing rules out an active leak that would recreate the void after the lift. Epp does not fix the leak. A plumber does, but we will not lift a slab over an active leak. 2. Foundation wall movement. A basement slab drop near a wall can mean the wall is moving in (a separate scope) rather than the slab settling. Epp checks for wall bowing and shear cracks before quoting. 3. Crack pattern and width. Hairline shrinkage cracks across an interior slab are normal and do not affect liftability. Cracks wider than 1/2 inch through the slab thickness usually mean the slab needs replacement, not lifting. 4. Floor finish condition. Carpet, tile, vinyl, hardwood. Epp drills through the finish layer to inject foam, and the homeowner restores the floor finish after the lift. The finish condition affects how many ports we can place and where. 5. Sub-slab moisture and soil type. A 1- to 2-inch test bore through the slab in a discreet location confirms what is below. Loess, fine sand, clay, or original engineered fill. The soil type changes which lift method works. ## How Epp lifts an interior slab

When the diagnosis clears the slab for lifting, Epp uses polyurethane foam injection through 5/8-inch ports drilled through the floor finish and the slab. Foam is the right answer for interior slabs because the holes are small (5/8 inch versus the 1 1/4 inch a cement slurry lift needs), the cure is fast (about 15 minutes per port, slab walkable same day), and the foam is hydrophobic. It does not re-saturate clay soils the way cement slurry can. Floor finishes are protected with drop cloths and dust containment during drilling. After the lift, ports are patched with color-matched concrete patch material; the homeowner restores the floor finish above (carpet repair, tile replacement, vinyl patch) as a separate step. Epp also calls this approach mid-soil injection when the foam is targeted at the sub-slab fill layer 1 to 4 feet below the slab rather than the immediate sub-slab void. On a hydroconsolidated loess slab the void is rarely right at the slab bottom. It is in the densifying fill below, and the lift mechanism is compaction of that fill plus expansion to fill the airspace.

Nebraska and western Iowa sit on windblown loess that can run 30 to 100 feet deep. Slab-on-grade homes built in the 1960s through 1990s placed loess back under the slab as fill without modern compaction standards. Over 30 to 50 years that fill slowly hydroconsolidates and the slab drops. The 50-plus freeze-thaw cycles NE and IA see each winter do not directly affect interior slabs (the heated interior keeps the slab above freezing) but do affect basement slabs near exterior walls if the backfill outside is moving. Kansas and Missouri interior slabs more often deal with expansive clay heave from slab plumbing leaks. A pinhole leak in a copper line under the slab can wet the clay below it for years before the homeowner notices the floor moving. The clay heaves first, then drops when the leak is finally repaired and the clay dries. After 30 years of repairs across the region, we see the loess and clay patterns repeat in Lincoln, on concrete leveling work in Omaha, Council Bluffs, Kansas City, and St. Joseph.

Epp Foundation Repair lifts the slab. Epp does not repair or restore floor finishes. Carpet, tile, vinyl, hardwood, and laminate restoration is done by the homeowner or a flooring contractor after the lift. Epp does not fix plumbing leaks below the slab. That is a plumber's scope and has to happen before the lift if an active leak is found. When a slab is too cracked to lift as a unit, we say so on the Customized Repair Estimate and price removal and a new pour instead. Epp does not address interior wall settlement, sagging floor joists, or framing repair in the same scope. Those are separate trades or separate Epp services. Epp Foundation Repair is BBB A+ rated and a two-time BBB Integrity Award winner (2011 and 2016). Every interior slab lift comes with a written scope, a measured lift target at every grid point, and Epp's 5-year PolyLift warranty against failure of the material to lift or stabilize due to defects in materials or workmanship. Transferable to a future homeowner.

Multi-room lifts and larger square footages go up from there. Customized Repair Estimate after on-site inspection reflects your scope. If the floor has a noticeable slope, a door has fallen out of square at the bottom, a crack in the slab has dropped on one side, or the floor sounds hollow when tapped, schedule a free inspection. The longer a slab settles, the more soil moves out from under it, and the more expensive the eventual lift becomes.