How Foam Injection Fills the Void Under a Slab
Polyurethane foam injection restores the support your concrete lost: it fills the gap, densifies the soil, and lifts the slab back to grade, all through coin sized holes.
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What to know about polyurethane foam injection, and when it's the right call.
The foam is delivered as two liquid components that stay inert until they meet at the injection nozzle. Combined, they react within seconds, expanding to many times their liquid volume and generating pressure as they go. That sequence is the mechanism: the expanding resin first follows the path of least resistance into the void, filling it completely, including channels and pockets a shovel could never reach. As it expands it compacts the loose, disturbed soil at the void's edges, turning a soft zone into a firm one. Only when the void is filled does the continued expansion begin lifting the slab, and because the crew injects in small shots while watching elevations, the lift arrives in fine increments that stop exactly at grade. Within minutes the foam cures into a rigid, closed cell base that resists water and does not compress under traffic. The drilled holes are patched with concrete, and the only evidence of the repair is a level slab sitting where it was originally poured.
The symptoms that usually lead to polyurethane foam injection are on the concrete leveling problem signs page, alongside the other signs that point to the same underlying cause.
How we install polyurethane foam injection.
Free evaluation
We measure elevations across the slab, locate the voids, and identify the soil or water condition that created them. You get the findings in writing.
Ground penetrating radar scan on interior floors
Driveways, patios and sidewalks are open ground. An interior floor is not, so any interior work gets a radar scan first, and a post tension slab requires one in every case. The scan maps the concrete thickness and the spacing and depth of what is set inside the slab, and the port layout is then drawn around those findings rather than over them. It runs at a two hour minimum and is an additional line where the proposal does not already include it. A garage floor that has dropped is the common case where this applies.
Drill injection ports
Coin sized holes are drilled through the slab, positioned so the foam reaches every part of the void.
Inject, fill, and lift
The expanding foam fills the void, densifies the surrounding soil, and raises the slab in monitored increments back to grade, the concrete lifting and leveling step itself.
Patch and verify
Ports are patched, final elevations are compared against the starting survey, and the surface is typically in service the same day.
Lifted back to level. Not torn out.
Expanding foam is injected under a sunken slab through ports the size of a coin. It fills the washed-out soil beneath, then gently floats the concrete back up to the level line. The same slab, saved.
Polyurethane Foam Injection on a real project.
Polyurethane foam injection restores the support your concrete lost: it fills the gap, densifies the soil, and lifts the slab back to grade, all through coin sized holes.
Care and expertise from a team that's been doing this since 2011.
When the fix is polyurethane foam injection, the installer matters as much as the method. Dalinghaus crews handle foundation, concrete, and crawl space work across California, Arizona, and Nevada, and nothing else.
Foundation repair, concrete leveling, and crawl space repair are our entire focus. Not a sideline.
More than 2,000 projects on the clay and desert soils of California, Arizona, and Nevada since 2011.
CSLB License #983851 in California, ROC #330307 in Arizona, and License #0089738 in Nevada. Look us up with the state before we ever set foot on your property.
Warranty terms come in writing with every proposal, and the terms that apply to your job are stated in that job's paperwork. Ask your project specialist during the free evaluation.
Answers to common questions about Polyurethane Foam Injection.
Don't see your question here? Our team is happy to help. Reach out anytime.
Two jobs, often on the same project: filling voids beneath concrete so slabs regain continuous support, and lifting settled slabs back to level. We use it under driveways, walkways, patios, pool decks, garage floors, interior slabs, and commercial floors, anywhere the soil left a gap and the concrete above is still sound.
Other concrete leveling solutions we install.
Every solution is engineered for a specific soil profile and failure mode. Browse the full toolkit.
Concrete Grinding
Where a slab has stopped moving and one edge stands proud, shaving it flush removes the hazard in a visit. Where the slab is still moving, it only resets the clock.
Learn more
Concrete Void Filling
A void is a gap the concrete is bridging. Concrete void filling, done before the slab finds out, is the cheapest version of this repair anyone will ever offer you.
Learn more
Polyjacking
Polyjacking injects expanding polyurethane under a sunken slab, raising it in minutes through coin sized holes. Light on the soil, hard under the load.
Learn more
Slab Jacking
Slab jacking lifts sunken concrete from below, through small holes, back to the level it was poured at. Here is how the method works and how we choose the material.
Learn moreFrom free evaluation to installed polyurethane foam injection.
How a polyurethane foam injection project moves from diagnosis to completed installation.
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Get your repairs.
Our crews complete the work on schedule, with the findings and scope in writing from the first visit.
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Before you choose who installs your polyurethane foam injection, read how homeowners across California and Arizona rate our work.
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