Looking for information about drilled concrete piers for foundation repair? If so, don’t hit that back button because that’s what this article is about. We’ll review drilled concrete piers, what they’re used for, how they’re installed, and why they’re not the best foundation repair method.
What Are Drilled Concrete Piers?
Drilled concrete piers are used in foundation repair and for new construction projects requiring a deep foundation system because of unstable soil conditions.
Drilled concrete piers provide structural support by transferring the weight of a building onto a deeper, more stable soil layer. You’ll hear drilled concrete piers referred to as caissons, cast-in-situ piles, and drilled shafts, among others.
The installation process for drilled concrete piers involves drilling a hole in the ground and then filling it with concrete. The process is repeated until the required number of piers are installed and adequately spaced to support the weight of the building.
How Drilled Concrete Piers Are Used For Foundation Repair
Drilled concrete piers are sometimes used to stabilize homes constructed on hillsides experiencing lateral movement due to a phenomenon known as slope creep. Drilled concrete piers are also used to stabilize foundations experiencing issues due to problematic soils (expansive, erosion-prone, etc.) that tend to shift and move over time, leading to foundation trouble.
How Are Drilled Concrete Piers Installed?
The installation procedure for drilled concrete piers is as follows:
- Excavation – The first step involves drilling a hole in the ground to the required depth. This is typically done using an auger, a type of drilling equipment that can dig deep holes.
- Reinforcement – Once the hole has been excavated, the next step is to add steel reinforcement. This is done by placing a steel cage or rebar into the hole, providing additional strength and stability to the pier.
- Pouring the concrete – The final step in the installation process is pouring in the concrete. A mix of concrete is poured into the hole, filling the space between the excavation and the steel reinforcement.
- Curing – After the concrete has been poured, it’s essential to leave the pier undisturbed for a period of time to allow the concrete to cure (i.e., harden). This can take up to a month, depending on the size and specific needs of the pier. Once the pier has fully cured, it’s ready to support the weight and load of the structure.
Drilled Concrete Piers Are Not the Best Foundation Repair Method
While their low cost may seem attractive, the drawbacks of drilled concrete piers outweigh their benefits. These include the following:
- Drilled concrete piers are vulnerable to water damage – This damage includes rusted rebar and concrete spalling.
- Drilled concrete piers may not be able to reach load-bearing soil – This can result in the foundation settling and shifting over time.
- Insufficient load capacity – Another critical factor to consider is the maximum load capacity of drilled concrete piers, which is only around 8,000 pounds. That may be insufficient to support the weight of a typical house.
- Inability to raise foundation to maximum practical level – Drilled concrete piers offer no opportunity for lifting your home to maximum practical level, or as much as possible without causing damage to the foundation.
Dalinghaus Construction does not install drilled concrete piers for the above reasons. Instead, we use push piers, helical piers, and slab piers to correct foundation settlement. These underpinning solutions aren’t vulnerable to water damage, are able to reach load-bearing soil, offer higher load capacity, and enable your home to be lifted to maximum practical level.
Most Common Causes of Foundation Trouble
The most common causes of foundation problems include the following:
- Expansive soil – Expansive soil is one of the most notorious culprits. This type of soil swells as it absorbs moisture and shrinks as it dries, creating movement under the foundation that can lead to severe structural damage.
- Erosion-prone soil – Erosion-prone soil is another significant cause of foundation issues because it can cause voids to form in the ground under the foundation. If the foundation settles into the voids, structural damage will likely occur.
- Inadequate soil preparation – When soil isn’t compacted enough before construction starts, the foundation could eventually settle into the ground unevenly, leading to structural damage.
- Seismic events – Earthquakes can also cause foundation problems. Tremors create movement under the foundation, leading to cracks and other structural damage.
- Poor drainage – When excess water isn’t channeled away from the foundation, it can seep into the soil around the structure and cause a lot of trouble.
- Weather changes – Weather changes, such as extreme heat or cold, can also play a role in foundation problems. For example, in areas with high temperatures and low humidity, the soil can dry out, causing voids to form under the foundation. On the other hand, in areas with high levels of rainfall, the soil can become oversaturated, leading to soil subsidence and shifting, especially if you have expansive or erosion-prone soil under the foundation.
Tips on How to Help Prevent Foundation Problems
Fortunately, there are several steps homeowners can take to help prevent foundation damage. Since the leading cause of foundation trouble is water, most of these measures involve controlling groundwater around the foundation:
- Regrade your yard, if necessary – This process involves altering the slope of the ground around the foundation to control the water flow. When a yard slopes towards the house, groundwater can quickly accumulate around the foundation and cause problems. Regrading the yard ensures groundwater drains away from the foundation.
- Use downspout extensions – Downspouts are designed to direct rainwater away from the roof and foundation of the house, but without extensions, the water can still pool near the foundation. By adding an extension to the end of the downspout, water can be safely directed away from the house before release.
- Clean gutters regularly – Clogged gutters can prevent water from draining properly toward the downspouts. By ensuring that gutters are debris-free and working correctly, homeowners can prevent water from accumulating around the foundation and causing damage.
- Install a drain tile system – A drain tile system is a network of buried drainage pipes that collects and disposes of excess water in the ground around the foundation.
- Keep trees away from the foundation – While trees can add shade and beauty to a property, their roots can wreak havoc on a foundation. As roots grow and spread, they can cause the soil under the foundation to shift, leading to severe structural damage.
If you think your home might need foundation repair, contact us today to schedule an evaluation. If we find a problem, we’ll give you a repair estimate. We serve Southern California, Arizona, and Nevada.