Technology in the foundation repair industry evolves quickly – partly because it’s a competitive patenting scene and partly because newer, better, and longer-lasting methods of foundation repair are what the consumer want. Underpinning, a form of foundation repair, is no exception to this full-tilt survival-of-the-fittest evolution.
It can feel a bit daunting – how are you supposed to be “in the know” for underpinning cutting-edge technology? What foundation repair methods are in and what are out?
Well, with over 100 years of combined experience in the foundation repair industry, we can help you navigate the quickly evolving world of underpinning when it comes to antiquated methods.
Underpinning is when a structure is strengthened and reinforced by extending the depth of a foundation. For example, newer methods of underpinning include push pier underpinning and helical pier underpinning.
This methodology utilizes hollow, galvanized steel tubes as underground stilts driven into bedrock. These piers can withstand upwards of 68 thousand pounds worth of pressure and are currently the industry standard of underpinning across the nation.
To learn about the installation process, specs, and pros of push piers and helical piers, read our articles The 5 Steps to Push Pier Foundation Repair and The 5 Steps to Helical Pier Installation.
Despite the recent advances on the underpinning technological scene, there are 2 antiquated methods of underpinning which have yet to die out: mudjacking and concrete piles.
In this article, you will learn the cons of mudjacking and concrete piles, and why we believe here at Dalinghaus these underpinning methods should go the way of the buffalo.
Problems with Mudjacking
Mudjacking is a concrete leveling technique that injects limestone or mortar slurry underneath a settled structure.
The sheer force and pressure propel the structure upward with the ultimate goal of returning the building to level (recovering lost ground from foundation settlement). Mudjacking relies on the incredible installation force, rather than the expansive properties of the slurry, for the slab lift.
This technique is called mudjacking because both the limestone and mortar slurry are referred to as “mud” in the construction industry. And, this mud, quite literally, jacks up the structure. It’s simply a noun (mud) and a present participle (jacking) smashed together, efficient in language, not so efficient in implementation.
Mudjacking has a difficult time lifting the slab back into place because only so much mud can be forced into the injection holes. This slurry doesn’t expand like polyurethane, so mudjack-lifting reaches the maximum possible lift fairly quickly.
Mudjacking, when compared to the newer methods of push pier and helical underpinning, is invasive. Steel pier systems leave no trace, like a good cosmetic surgeon.
Mudjacking can leave ugly pockmarks in your slab about the size of a half-dollar or over 3 plus inches. These are the drill sites, where the hydraulic hose is fitted, and the mud is infused into the soil.
Of course, these holes are later patched over, but often the concrete patch doesn’t match the original slab. The implementation process can result in a grotesque eyesore; however, cosmetics is the least of your worries when it comes to mudjacking.
At its best, mudjacking is an inefficient, temporary fix. At its worst, it’s akin to wrapping an anchor around your home. Mudjacking does not combat foundation settlement well.
Foundation settlement occurs when the soil beneath a structure is too weak to withstand the structure’s weight. In the foundation repair industry, this soil is referred to as incompetent, non-loadbearing soil. This is mostly comprised of clays, loam soils, or any expansive soil that engorges or shrinks in direct correlation with the water table.
To support the lifted structure, mudjacking is dependent on the underlying soil – the same incompetent non-loadbearing soil that resulted in the initial foundation settlement.
Turns out, slurry is heavy, weighing in right around 100 pounds per cubic foot. So, the question is, what happens when you add weight to an already sinking structure?
Well, if there is no competent, load-bearing soil immediately beneath the newly added slurry (and this type of soil/bedrock is generally a good 20-30 feet down), then it sinks. Therefore, many contractors cannot guarantee their work.
On those numerous occasions when it does sink, some contractors suggest mudjacking again, twice is the charm. It is now a much more difficult procedure because the contractor must punch through the first round of dense, solidified mud before they can pour new mortar.
And, even if a second application is successfully administered, the odds are high it will sink again. In the end, gravity always wins.
Therefore, warranties on mudjacking are relatively short, say 1-2 years. On the other hand, steel pier systems (such as push piers and helical piers), enjoy a lifetime warranty across much of the United States.
Besides steel pier systems, mudjacking has been universally usurped by polyurethane foam, a far less invasive and lighter method. To learn more about the differences between mudjacking and polyurethane, read our article Polyurethane Injection vs Mudjacking (weight, application, and cure time).
So, you might be wondering, in the cutthroat world of foundation repair patents and new technologies, why do contractors still utilize mudjacking? It’s used because it’s a relatively quick, unsophisticated process that usually only takes a day and shows quick results.
In summary, the main problems with mudjacking are:
- Mudjacking can leave unsightly pockmarks in your slab
- Mudjacking can ultimately sink your home further due to the additional weight
- Mudjacking is not lifetime warrantied
- Mudjacking does not offer the long-lasting benefits of steel-pier systems or polyurethane injection
Problems with Concrete Piers
Concrete piers, piles, or mini piles are cylindrical pillars of concrete that support the weight of a structure after being implemented underneath a foundation.
These piers can either be precast (meaning they stand on their own) or cast-in-situ (where the concrete is poured into a prepared framework on-site).
Precast concrete piers are like steel pier systems in that they require excavation to be inserted underneath the structure. Cast-in-situ piers are similar to mudjacking in that they are applied in slurry form into a prefabricated mold constructed beneath the foundation.
Concrete piers are pretty much out of commission across the United States, or at least they should be. Unfortunately, some foundation repair companies still utilize these prehistoric piers.
The primary issue is that precast concrete piers don’t go deep enough to punch through the incompetent, non-loadbearing soil.
Due to their shape and density, they are not driven via hydraulic rams like push piers but rather secured underneath a home with bottle jacks. In short, the end result is a slightly extended footing by maybe 3 feet or so.
In this instance, we have the same issue as mudjacking. More weight is added that will invariably sink later due to the poor soil conditions.
Read more: Poly Injection VS Concrete Injection
In addition, concrete does not weather well. Rain seeps into expansive soil quickly and buried concrete piles soak in this wet soil for long periods of time. These concrete piles are not galvanized against moisture like steel pier systems.
Water soaks easily into concrete, rusts and corrodes the rebar, and causes the rebar to expand. The expanding rebar compromises the structural integrity of the concrete pier, resulting in large chunks of concrete breaking apart from the primary pier.
In addition, concrete is not as strong as the steel implemented for push and helical pier systems. Concrete piers typically max out at a maximum compression strength of 5,000 psi – a good 60,000 pounds below typical steel pier systems.
A few outlier foundation repair contractors still utilize concrete piers, but these underpinning contractors are far and few in-between.
In summary, the main problems with concrete piers are:
- Precast concrete mini piles don’t go deep enough to provide any real, permanent support
- Precast and cast-in-situ piles are susceptible to water damage (spalling and rusted rebar)
- Concrete piles do not provide near as much strength as steel pier systems
Concrete, in general, is susceptible to a whole host of issues. To learn about how water can induce concrete spalling (the primary culprit of the recent Florida Surfside condominium collapse), read our article: What is Concrete Spalling (Causes, Prevention, and Treatment).
Underpinning: Best Options for You
In this article, you learned the problems posed by mudjacking and concrete piles. Mudjacking typically only lasts a few years, can further exacerbate your sinking foundation, and can leave ugly pockmarks in your slab. Concrete piles are highly susceptible to water damage and don’t reach load-bearing competent soil.
As we mentioned above, technology is changing all the time. Cutting-edge methods of underpinning we here at Dalinghaus highly recommend are push pier, helical pier, and polyurethane underpinning.
Check out these articles to learn about the best forms of underpinning currently available on the market:
- How do Push Piers Work (Definition, Components, & Utilization)
- How Do Helical Piers Work?
- How Does Polyurethane Lifting Work?
The articles above will teach you how each separate form of underpinning works so you can be an active participant in choosing which foundation repair is right for you.
Check out our post: Mudjacking vs Steel Pier Systems Underpinning
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