Fill the Voids Under Your Foundation Before They Grow

It is the injection of a two-part expanding foam into the empty space that has opened under a slab foundation, a footing, or a stem wall, so the concrete is supported from below again. The foam mixes at the gun, expands within seconds, and cures into a firm, lightweight, closed-cell fill that resists water. It is mid-soil injection under the slab that reaches a maximum of about 4 feet, which is where voids under a house form.

No. This page is about the concrete a house sits on. Driveways, sidewalks, patios, and pool decks are flatwork, and Epp's concrete leveling crew fills and lifts those with the same foam under a different set of rules. A void under a foundation affects the walls, floors, and door frames above it, so the inspection here looks at the whole structure, not only at the slab surface.

Stabilization is guaranteed and lift is attempted. Filling the void stops the concrete from dropping further, and as the foam expands it sometimes carries a settled section partway back. Some slabs have cracked into pieces that move independently, and some sections cannot rise without cracking finishes above them, so the crew lifts in small stages and stops where the concrete is supported. Epp says on the first visit what is realistic for your home.

The cured foam is closed-cell, so it will not wash out or shrink the way loose fill does, and the space it fills stays filled. It cannot stop a new void from forming if the cause is left alone, such as a line still leaking under the slab or clay shrinking away from the footing through every dry summer. That is why the crew names the cause and the simple fix, usually a plumbing repair or moving water away from the house. Correcting the source is part of a lasting repair.

A floor that slopes toward one area, cracks opening across the slab floor, a hollow sound when the slab is tapped, interior doors that no longer latch, and cracks at the corners of door and window openings. A water bill that jumped a few months before the floor moved usually points to a leak under the slab, and a wet corner after every storm points to a downspout or grading problem on that side of the house.

When the bearing soil itself has failed rather than washed out. Foam fills a void, but it needs sound soil beneath it to push against. If the soil under the footing is saturated clay still moving or fill that was never compacted, the foam would fill the space today and the foundation would settle again. That is when Epp installs piers to competent soil and uses foam only to fill what remains. The Customized Repair Estimate states which one applies to your home. When the slab has dropped as well as lost support, slab jacking for slab foundations is the next step.