Polyurethane Foam Slab Lifting

The pool table proved it first: every ball drifted to the same corner of the game room. Then the tape measure confirmed a floor dip you can rock a chair in. One contractor quoted piers at $9,000. Another said foam could fix it for a third of that in an afternoon. Both might be right, because they are describing different problems, and which one you have is the entire decision.

How foam lifting works

A technician drills small holes through the sunken concrete, threads injection ports into them, and pumps in a two part polyurethane that reacts and expands within seconds. The foam fills any void first, then builds pressure and lifts the slab. Because it cures in minutes rather than days, the crew can raise a floor in staged passes, checking elevations as they go, and you can walk the surface the same day.

The material is light, roughly a few pounds per cubic foot once cured, so it adds almost no weight to soil that is already struggling. That is the core advantage over the old sand and cement slurry approach, and our foam vs mudjacking comparison covers that matchup in detail.

Where foam is the right tool

Foam earns its keep on concrete that sank as a panel while the structure around it stayed put: interior floor dips over poorly compacted fill, garage slabs that settled away from the house, patios tipping toward the back door, driveways, sidewalks, and pool decks. It is also the standard fix for filling washout voids under slabs even when no lift is needed.

What foam cannot fix

Foam lifts concrete. It does not underpin a house. When the perimeter grade beam is settling, when brick is cracking in stair steps and doors are racking out of square, the structure needs pier support at the footing, and foam under the middle of the floor will not change that. Injecting foam onto clay that is still shrinking just buys a well supported ride on the same elevator.

An elevation survey sorts this out quickly. Panel settlement shows as an isolated dish in the readings; structural settlement shows the whole edge of the house stepping down. Insist on seeing which pattern your floor makes before choosing the fix.

The longevity questions worth asking

Three questions separate serious foam contractors from drill and bill crews. What density foam is being injected, and is it rated for the load above it? What does the injection pattern look like on paper, not just where does it feel low? And what does the warranty say about re lifting if the area settles again, at whose cost?

What it costs

Published industry cost data for the Georgetown area puts most residential foam work between $2,000 and $8,000. Square footage matters less than people expect; lift height and void volume drive the number, because the foam is the expensive ingredient. A quarter inch dip across a garage bay costs far less to correct than 2 inches under a den, and a job quoted without anyone measuring the lift is a guess. The cost guide puts foam in context next to pier pricing.