The Cost of Underpinning with Polyurethane Deep Injection

When you think about underpinning, polyurethane deep injection probably isn’t the first option to come to mind, but maybe it should be. 

Generally, push piers and helical piers are the all-stars of the underpinning scene with their proven track records and their .400 batting averages.

Steel pier systems prove amazingly proficient at providing localized support after they reach competent, load-bearing soil – rock bottom so to speak. Polyurethane, on the other hand, permeates the soil providing layers of broad and sweeping soil densification and lift. 

Polyurethane deep injection is the least invasive, fastest, and cheapest form of underpinning.  

You want to know more, obviously. In this blog post, we are going to cover:

  1. What exactly is polyurethane?
  2. What is polyurethane deep injection?
  3. What is the cost of polyurethane deep injection? 

1. What is Polyurethane? 

 Polyurethane foam is an injectable polyol and isocyanate resin sealantinsulationgrout that expands upon application, providing void fillstructural support, and re-leveling properties.

Polyurethane foam is waterproofflame-retardantnoninvasive, and non-polluting, weighing 3.5 to 5 pounds per square foot and reaching 90% compression strength after 15 minutes. Polyurethane can hold 7,200 pounds per square foot.

Polyurethane is utilized for diverse purposes, including footwear, bedding, furniture, seating – you name it. It is even safe enough to be implanted into the human body for various medical treatments, such as pacemakers and full heart valves.

The polyurethane foam we utilize here at Dalinghaus is AP LIFT 430, which is certified by Truesdail Labs to NSF/ANSI 61-5 (approved for contact with drinking water).

In other words, polyurethane is completely safe for the environment, poses absolutely no danger to your property, children, and pets. You can put your mind and heart at ease when utilizing polyurethane for deep injection.

*Note – Polyurethane is a superior alternative to mudjacking (which utilized slurried cement to raise a previously settled structure). Mudjacking can weigh 140 pounds per cubic foot, poly is only 5 pounds per cubic foot.

2. What is  Polyurethane Deep Injection?

Polyurethane deep injection is the systematic layering of polyurethane at different depths underneath your home, which densifies the weakly compacted, eroding soil. As the polyurethane expands, it quickly fills voids/fissures and coagulates, strengthening the weak soil.

For a comprehensive walkthrough of polyurethane injection, read our article: 5 Steps to Polyurethane Foam Injection (From Drill Holes to Cure).

For Polyurethane Deep Injection, the poly is injected in two phases:

Phase 1 – The polyurethane is injected 7-10 feet deep beneath the home.

Phase 2 – The polyurethane is injected 3-4 feet deep beneath the home.

We apply the deeper polyurethane first to avoid driving our application tubes through already hardened poly. These tubes are 7 to 10 feet long and act as ports to ensure the polyurethane makes it all the way down into the weak soil.  

Our two-phase system provides double the support, solidifying the soil directly beneath your foundation and the soil a little bit deeper. Once the polyurethane has been injected it diffused through the soil, pushing the soil together to compact it. 

The poly expands outwardupward, and downward – creating a type of foam island (or a foam foundation for your cement foundation). This expansive property also lifts your home back into place, leveling the foundation.

Polyurethane Deep Injection is occasionally coupled with push pier and helical pier underpinning but is also a solo application. 

3. What is the cost of Polyurethane Deep Injection? 

Polyurethane Deep Injection is the cheapest form of underpinning currently on the market. Now, just because it’s the cheapest option doesn’t mean it’s the best option for you (in that it will be the most effective).

While Polyurethane Deep Injection does provide some lift, we can’t confidently lift more than 1/2″ to 1″ with deep injections. Therefore, polyurethane is used primarily as a form of stabilization and directly addresses incompetent soil

Trust your foundation repair specialist to make the right call for your foundation repair plan.

Polyurethane Deep Injection underpinning is more expensive than your average polyurethane void fill due to the intensive labor and more sophisticated process.

PDI is priced at $160 per linear foot. The Dalinghaus polyurethane minimum of $2,500 remains the same, buying you a baseline of 15.5 square feet.  

Then the same math applies: 

$2,500 (for 15.5 square feet) + $160 x additional square feet.

Choose Dalinghaus for Your Underpinning Needs

In conclusion, Polyurethane Deep Injection is an affordable method of underpinning and densifying the soil underneath your home, providing solid structural support.

Be sure to check out our Ultimate Foundation Repair Guide for more information on polyurethane.

Your time is valuable, and we respect that. If you choose Dalinghaus, you will receive a repair plan tailor-fit to meet your specific needs. 

Dalinghaus Construction Inc. can help you fix your sinking foundation once and for all with helical pierpush pier, and polyurethane underpinning

We do foundation underpinning and retaining wall repair the right way. With over 100 years of combined experience and 4.9 stars out of over 300 reviews – we are here to ensure that you never settle

If you live in SoCal or Arizona and would like a FREE crack 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.

Related Posts

Leave a Reply

Your email address will not be published. Required fields are marked *