Applications of Polyurethane: Void Fill, Slab Leveling, and Slab Lifting

So, your sidewalk sunk into the muddy mire that used to be your backyard before Fifi dug it up. Or perhaps your cement patio has a new severe slant to it so that you shimmy folded-up pieces of paper underneath your picnic table to make it artificially level. Or maybe you have weak, non-loadbearing soil and your pool is starting to crack due to the strain. The question is: how do you lift and relevel large sections of concrete?   

Polyurethane is a panacea, a cure-all, for a long list of soil-related issues. Polyurethane can lift, level, and densify weak soil. Dalinghaus Construction Inc. has been in the foundation repair industry for decades. We are here to educate you on everything to do with polyurethane, whether you choose to employ our services or go with another contractor.

In this article, you will learn the properties of polyurethane foam, how it is utilized for soil densification, slab lift & leveling, and void fill.


What is Polyurethane Foam?

Polyurethane foam is an injectable polyol and isocyanate resin sealant, insulation, grout which expands upon application providing void fill, structural support, and re-leveling properties. Polyurethane foam is waterproof, flame-retardant, noninvasive, and nonpolluting, weighing 3.5 to 5 pounds per cubic foot and reaching 90% compression strength after 15 minutes. Polyurethane can hold 7,200 pounds per square foot.

Polyurethane Foam is injected as a liquid before it solidifies into its foam state. Due to the initial liquid form, polyurethane permeates into tight spaces, allowing it to penetrate weak soil and difficult to reach voids. This foam is environmentally inert, posing no danger to the environment or the evolutionarily finely tuned habitat that is your yard.  

In other words, your children and your furry pets are safe. In fact, polyurethane itself is so safe it is used in pacemakers and other devices that can be safely implanted into the body.

At Dalinghaus Construction Inc., we utilize AP LIFT 430, which is certified by Truesdail Labs to NSF / ANSI 61-5 (meaning it’s approved for contact with drinking water).

Fun Fact with Brian – Polyurethane has quickly usurped mudjacking due to its lighter weight and less invasive application system. Mudjacking weighs up to 140 pounds per cubic foot (which just adds more weight to an already sinking slab). To find out why Polyurethane is a better option than mudjacking, read our article Polyurethane Injection vs Mudjacking (Weight, Application, & Cure Time).

Polyurethane Soil Densification

Polyurethane foam densifies weak, non-loadbearing, expansive soils, such as clays and lay stratum. The polyurethane is pumped deep into the soil (often at varying levels/intervals) and expands as a foam. The polyurethane foam fills gaps and underground pockets that compromise the structural integrity of the soil. This foam solidifies, strengthening the soil by adding light, water retardant support. Polyurethane soil densification can be used to mitigate landslides, for hillside stabilization, and deep injection.   

Polyurethane Slab Lift & Leveling

Sidewalks, concrete patios, and backyard basketball courts can sink and become uneven. While it’s tempting to blame the slanted slab for your bad dribbling skills during a pick-up game, it’s always more fun and safer to walk across flat, level surfaces.

A flat working space is especially important in a warehouse environment. Polyurethane foam works beautifully at leveling warehouse slabs to ensure all the warehouse workers are safe. To learn more about warehouse safety, read our article Warehouse Floor Repair (Alchemy-Spetec).  

Polyurethane is the perfect candidate to lift and relevel concrete surfaces, due to the expansive properties of the foam. As the foam expands, it pushes upwards, exerting a tremendous amount of force on the slab above, returning it to level.  

Check out our case study: Lifting A Garage With Polyurethane in La Habra Heights

Polyurethane Void Fill  

Polyurethane foam is often utilized as a void fill after a slab lift during an underpinning project. When the affected section of the home is lifted, it leaves a void where the home had settled. Polyurethane is injected, the foam expands, and the void is filled with strong, durable, and supportive material.

*Note – The lifted section of the home always requires void fill (the last pier on each side is referred to as the void fill lifting point). The entire area beneath the slab doesn’t require void fill, only the affected area.  

 Dalinghaus Construction Inc. has a void fill minimum of $2,500 which buys 250 square feet of void fill. In addition, we warranty all our polyurethane projects for 5 years.  

Polyurethane Projects

In this article, you learned about various applications of polyurethane foam in the construction world: soil densification, slab lift & leveling, and void fill.

If you want to learn how invasive polyurethane injection is, read our article 5 Steps to Polyurethane Foam Injection (From Drillholes to Cure) 

We have over 100 years of combined experience in the foundation repair game. We are here to educate and assist, whether you ultimately choose us for your polyurethane services or not.

Read more: How to sell a home ‘AS IS’ with a Foundation Problem?

If you live in Southern California or Arizona and would like to book a free foundation inspection, click the link below –


Brian Dalinghaus

Brian is one of the Co-Founders of Dalinghaus Construction. He has been in the foundation repair industry since 2005. During his career, he has been associated with helping over 4,000 homes and structures throughout California and Arizona.

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