piles vs piers comparison

Foundation Repair Methods Comparison: Drilled Piers vs. Pressed Pilings

It has recently come to your attention that foundation repair is needed on your BCS home. You might be working on getting estimates or haven’t started yet. Did you even know that there are different methods of foundation repair to choose from in the Brazos Valley?

Anchor Foundation Repair Bryan College Station

At Anchor Foundation Repair, we have repaired over 4,000 slab foundations in the Bryan-College Station area and surrounding communities like Brenham and Caldwell since 1985. We can tell you about our method of foundation repair, and the others readily available in our area.

In this article, we will compare and contrast how each of these methods works and outline their pros and cons. We will also present some situations or homeowner types that each method might be best suited for. 

By the end of this article, you should be able to identify a method that speaks to your needs and will likely serve you best. 

Similarities Between Pier and Piling Foundation Repair Methods

The two readily available methods of slab foundation repair in our area are drilled piers and pressed concrete pilings. The two methods have some similarities. Both involve using vertical support structures (piles or piers) to lift, level, and stabilize the home post-construction, a process known as underpinning. 

It’s comparable to a beach house on stilts, but the home rests on supports buried underground instead of above ground. 

Foundation Repair Plan

Both methods require a similar number of piers or piles for the repairs, and that’s where the similarities end. The differences between the two methods lie in the construction, installation, and functioning of these supports, which we discuss in the next section.

*Full Disclosure* Even though we do have a preference in methods and only use one of them, we recognize that each home and homeowner has unique needs and that there is no perfect solution for all scenarios. 

Concrete Pressed Piling Method Overview

There are steel and concrete pressed pilings. In this article, we are only talking about concrete pilings. Pressed concrete piles are commonly available in our Bryan-College Station/Brazos Valley area from a few companies.

Construction of Pressed Pilings

Concrete pressed pilings, also known as “pressed piles,” are constructed using pre-made concrete cylinders. Each cylinder is 6″ in diameter and 12″ tall. They can be plain cylinders or have holes in the center. 

concrete pressed piling foundation repairs

The cylinders with holes can be connected during installation using steel cables or rebar, creating a variation called “cabled concrete pressed pilings” in the industry. 

These precast cylinders, with or without holes, are brought to your home for use in the foundation repairs. A pile cap, another pre-made concrete piece with a wider surface area on top, is placed on the cylinders.

Installation of a Pressed Piling System

To install a pressed piling system, contractors use a hydraulic jack to push concrete cylinders into the ground one by one. They continue stacking the cylinders until they can no longer be inserted into the soil. 

The pressed piles are placed at required support locations, topped with a pile cap, and then the home is raised using jacks and secured in place with shims. This simplified explanation provides an easy understanding of the installation process for the everyday homeowner.

How Pressed Piles Work in the Ground

how pressed pilings work in the ground

Pressed piles work by utilizing tension forces to support the home. It’s similar to a battery being held in place by a spring on one end. 

In this case, the expansive clay soil beneath the pile acts as the “spring,” exerting an upward force against the weight of the house. The soil also creates friction against the sides of the cylinders, keeping the pilings suspended in place. 

The combined forces from all sides, including gravity pushing down on the home, the soil pushing up on the pile, and the soil exerting force along the surface, work together to raise and stabilize the home in the desired position for foundation repair.

Pros of Concrete Pressed Pilings

Concrete pressed pilings offer two significant advantages:

  • Lower cost, and
  • Quicker installation time.

For homeowners seeking an affordable repair option or a speedy solution, pressed piles are a viable choice. The installation process typically takes only a couple of days. If cost-effectiveness and quick turnaround are your top priorities, the pressed pile method is likely the best option for you.

foundation repair method pros and cons

Cons of the Pressed Pile System

The downside to choosing pressed piles is that they are not as long-lasting for a few reasons that we will elaborate on below. 

  • Moisture level on installation day affects longevity,
  • No assurance the piling was installed with vertical alignment, and
  • Live load at installation time can be a factor in long-lasting stability.

Moisture Levels on Installation Day Affect Longevity

Moisture levels on the installation day significantly impact the longevity of the pressed pile method. The tension and effectiveness of the piles rely on the moisture content of the soil, which pushes against the weight of the home. 

If the soil becomes drier after installation, the tension weakens, requiring the home to shift or lose its position of tension. Conversely, if the ground becomes wetter, tension increases, potentially causing the piles to push up and the home to become uneven.

expansive clay
Texas Summer Soil

The climate and moisture content during installation can vary, leading to different outcomes and the use of varying numbers of cylinders for each repair job. For example, a dry summer day may result in less depth for a repair on an older, lighter home, while a wet winter day could require deeper installation and more cylinders for a newer, two-story stone house.

Considering that moisture levels change throughout seasons in the Texas climate, relying on soil moisture for tension and friction in pressed piling becomes problematic.

No Assurance the Piling Was Installed With Vertical Alignment

During installation, a potential drawback is that the pressing down of the cylinders may be disrupted by obstacles like rocks, roots, or dense soil, causing them to deviate from vertical alignment. Since the cylinders are pressed into the ground without a pre-dug continuous path, the installer cannot detect if this misalignment has occurred.

When the pile of cylinders is not vertically aligned and lacks proper interconnection, it raises concerns about the stability and durability of the repair. Additionally, if the pile does not reach sufficient depth due to drier soil, its long-term load-bearing capacity may be compromised.

Live Load at Installation Time Can Be a Factor In Long-Term Stability

A minor drawback is that the live load, which includes furniture and other items inside the home during installation, can impact the longevity of the pressed pile method. Changes in weight, such as adding or removing items, can alter the tension and potentially compromise the effectiveness of the foundation repairs over time.

best fit for foundation repair

What Situations or Homeowners Are Concrete Pilings Best For?

The pressed concrete pile system can be beneficial for certain scenarios and homeowners. Here is the shortlist of times when this method might be most appropriate for your situation.

  • A homeowner that is selling soon and is not interested in longevity.
  • An investor looking for a quick turnaround time.
  • A homeowner with limited funds who wants the least cost to complete the repair.
  • An investor who is trying to keep a remodel flip under a certain budget.
  • Anyone who doesn’t want the repair crew to be on site for a long time.
pressed piles vs drilled piers

Drilled Bell-Bottom Pier Method Overview

Drilled bell-bottom piers are similar in concept to footings created during the construction of large commercial buildings. The piers penetrate the ground and lower the foundation into non-reactive soil levels.

Construction of Bell-Bottom Piers

Bell-bottom piers are constructed on-site by first digging a hole and drilling a straight shaft into the ground. At the bottom of the shaft, a spinning tool creates a bell shape, widening the base of the pier. 

bell-bottom pier foundation repair

Steel rebar is inserted for reinforcement, and then concrete is poured into each pre-drilled hole, typically 10 to 12 feet deep. Finally, a steel-reinforced concrete cap is added. 

After pouring the piers, there is a waiting period of about 7-10 days for the fresh concrete to cure and gain maximum strength.

Installation of Bell-Bottom Pier System

drilled pier specs

The bell-bottom pier system is constructed and installed simultaneously on-site. Due to the manual construction process, it requires skill and experience to effectively install this system.

How Bell-Bottom Piers Work in the Ground

Bell-bottom piers resist uplift caused by expansive clay soils regardless of the soil’s moisture level. The bell shape provides an anchoring effect, preventing the pier from pushing up during wet seasons and sinking down during drier conditions. This wide-based footing, similar to commercial building construction, creates a strong and stable platform to elevate the home back to its original position.

Pros of the Bell Bottom Pier System

The bell-bottom pier system offers several key advantages. Firstly, it provides long-lasting stability to the home, as the on-site drilling ensures accurate installation without deviations in the path of the pier. 

pros and cons foundation repair

Additionally, independent engineering evaluations have confirmed that this system effectively resists uplift and settling, surpassing the capabilities of pressed piles, thanks to its wide bell-bottom base. Unlike other methods, the effectiveness of bell-bottom piers is not reliant on the weight of the home or the soil moisture content remaining the same after installation.

Cons of the Bell-Bottom Pier System

The bell-bottom pier system has its drawbacks, including a longer installation process and higher cost compared to concrete pressed pilings. 

Longer Installation Time

waiting for foundation repair

Due to on-site construction and the required curing time for the poured concrete, drilled piers take longer to install than pressed piles

The construction involves multiple steps such as digging, drilling the shaft, and manually pouring the concrete, which demands a skilled repair team with expertise in each phase of the process.

Higher Cost of Drilled Piers: Pro or Con?

The cost of drilled piers is higher due to the additional time and skill involved in the process compared to the pressed pile system. However, whether this is considered a pro or con depends on the individual’s perspective and the importance they place on the adage, “You get what you pay for.”

What Situations or Homeowners Are Bell-Bottom Piers Best For?

  • A homeowner that loves their home and plans to stay in it for the duration.
  • A homeowner that wants to pass their home down to their children someday and doesn’t want them to have to worry about this repair later.
  • A homeowner that loves their home and is planning a fabulous remodel someday.
  • A homeowner that had made many memories in their home and wants the best care and maintenance for it.
  • A lightweight home that does not have enough mass to make pressed piles function properly. This would be true of small, older homes.

Choosing the Best Foundation Repair Method For You

choosing a foundation repair company

Choosing the best foundation repair method is a personal decision based on individual goals and needs. Bell-bottom piers offer tailor-made fit, durable solutions that require skill and experience. 

Pressed pile repairs, on the other hand, provide a functional mass-produced option, with durability influenced by installation conditions. 

Both methods have their merits and the one you choose should meet your main goals, which aren’t the same for everyone. Here’s an article that helps identify your top needs when choosing a foundation repair company and method.

Choosing Foundation Repairs in Bryan-College Station

Foundation repair companies in our area specialize in different methods. We live in a smaller community and don’t have a great number of choices in each repair method type. So really when you are choosing a foundation repair contractor around here, you are also choosing a specific repair method. 

foundation repair inspection

Anchor Foundation Repair chooses the bell-bottom pier system and has been perfecting it for 35+ years in the Brazos Valley. We love that drilled piers have guaranteed depth, confirmation of a straight shaft, a wide base that resists both uplift and settling, and are not dependent upon climate conditions at the time of installation.

Anchor is best for homeowners who want to take the time to get the highest quality repair and the longest-lasting results so that you never have to worry about your foundation again. Learn more about the general inspection process for foundation issues to see if you’re ready for the next step.