Pressed Piling With Insert Method of Foundation Repair
- By Martin Dawson
- Published 09/23/2011
- Real Estate
- Unrated
The Pressed Piling with Insert method of foundation repair was developed in the 1990s in an effort to eliminate one of the disadvantages with its predecessor, the pressed piling method. Unfortunately, the pressed piling with insert method of foundation repair has a number of disadvantages. This article will discuss the advantages and disadvantages of this method.
Pressed piling with insert was preceded by the simple pressed piling method. Prior to both of these methods the accepted and widely used method of foundation repair was the poured concrete with steel rebar method, also known as the Bell Bottom Pier method. This was, and still is, a proven and time tested method but it requires higher material costs for more concrete and steel and higher labor costs. This method also requires a couple of weeks to complete rather than days, primarily due to the required curing time of concrete. Therefore, the pressed piling and pressed piling with insert methods were developed. They significantly cut both material costs and labor costs.
The primary advantages of Pressed Pilings with Inserts include a short total job time. This method does not utilize poured concrete and therefore there is no curing time. This method can be completed in a day or two. Another advantage is that the cable or steel rebar can help keep the piles aligned if it is inserted during the driving process. It is of little benefit if it is inserted after the piles have been pushed into the soil.
The first disadvantage of the pressed piling with insert method of foundation repair is that it relies on the weight of the home or building structure to push concrete cylinders (piles) into the ground. A lever or hydraulic jack is used to push one concrete pile into the ground by using the weight of the home. Then another concrete pile is placed on top of the first and both piles are pushed together. Additional concrete piles will be stacked in a vertical column and pushed into the ground until a refusal point is reached. At this point the work crew should stop immediately. The weight of the home
or building will NOT push the cylinders any further into the ground at the refusal point. If the work crew continues their attempts to push concrete cylinders past the refusal point, they could cause serious damage to the foundation they are trying to repair. The refusal point is very important because the final depth of the concrete piling is limited by the weight of the home or building. It is possible that the refusal point is reached before the pilings have reached stable soil.
The second disadvantage of the pressed piling with insert method of foundation repair is that the column of cylinders being pushed into the ground can become misaligned. The goal is to have a vertical column of cylinders under a portion of the foundation to provide support. If the column becomes misaligned for any reason then it offers minimal support for the foundation. This was and still is a major problem with pressed pilings. To address this problem the concrete piles were manufactured with a hole in the center to allow a steel rod or cable to be inserted. But this approach has its own set of problems. If the concrete cylinders are not perfectly aligned then it is impossible to thread a steel rod to the bottom-most cylinder. Other contractors attempt to “snake” a cable through the concrete cylinders and therefore “string” them together. But if the cable is not given any tension, either during or after the installation, it offers little or no help in resisting the natural forces of vertical and horizontal soil movement. In addition, there is no guarantee the cylinders are not “wandering” off at an angle. Neither the steel rod nor the cable will prevent misalignment 100% of the time.
Another disadvantage with the pressed piling with insert method is that the concrete piles have no steel reinforcement and any concrete cylinders cracked or broken during the pushing or driving process can not be seen. It is almost impossible to determine when this has happened but when it does happen the vertical integrity of the entire support column is in jeopardy.
In addition, holes in the concrete cylinders introduce a pathway for water. The water will seep down the hole and into the soil surrounding the cylinders and potentially weaken the soil.
Pressed piling with insert was preceded by the simple pressed piling method. Prior to both of these methods the accepted and widely used method of foundation repair was the poured concrete with steel rebar method, also known as the Bell Bottom Pier method. This was, and still is, a proven and time tested method but it requires higher material costs for more concrete and steel and higher labor costs. This method also requires a couple of weeks to complete rather than days, primarily due to the required curing time of concrete. Therefore, the pressed piling and pressed piling with insert methods were developed. They significantly cut both material costs and labor costs.
The primary advantages of Pressed Pilings with Inserts include a short total job time. This method does not utilize poured concrete and therefore there is no curing time. This method can be completed in a day or two. Another advantage is that the cable or steel rebar can help keep the piles aligned if it is inserted during the driving process. It is of little benefit if it is inserted after the piles have been pushed into the soil.
The first disadvantage of the pressed piling with insert method of foundation repair is that it relies on the weight of the home or building structure to push concrete cylinders (piles) into the ground. A lever or hydraulic jack is used to push one concrete pile into the ground by using the weight of the home. Then another concrete pile is placed on top of the first and both piles are pushed together. Additional concrete piles will be stacked in a vertical column and pushed into the ground until a refusal point is reached. At this point the work crew should stop immediately. The weight of the home
The second disadvantage of the pressed piling with insert method of foundation repair is that the column of cylinders being pushed into the ground can become misaligned. The goal is to have a vertical column of cylinders under a portion of the foundation to provide support. If the column becomes misaligned for any reason then it offers minimal support for the foundation. This was and still is a major problem with pressed pilings. To address this problem the concrete piles were manufactured with a hole in the center to allow a steel rod or cable to be inserted. But this approach has its own set of problems. If the concrete cylinders are not perfectly aligned then it is impossible to thread a steel rod to the bottom-most cylinder. Other contractors attempt to “snake” a cable through the concrete cylinders and therefore “string” them together. But if the cable is not given any tension, either during or after the installation, it offers little or no help in resisting the natural forces of vertical and horizontal soil movement. In addition, there is no guarantee the cylinders are not “wandering” off at an angle. Neither the steel rod nor the cable will prevent misalignment 100% of the time.
Another disadvantage with the pressed piling with insert method is that the concrete piles have no steel reinforcement and any concrete cylinders cracked or broken during the pushing or driving process can not be seen. It is almost impossible to determine when this has happened but when it does happen the vertical integrity of the entire support column is in jeopardy.
In addition, holes in the concrete cylinders introduce a pathway for water. The water will seep down the hole and into the soil surrounding the cylinders and potentially weaken the soil.
Martin Dawson
Martin Dawson is the co-founder of Dawson Foundation Repair headquartered in Houston, Texas. He is a leading authority on repairing failed commercial and home foundations using the time tested and thoroughly researched drilled Bell Bottom Pier method. His company has serviced Texas since 1984 and been a member of the Better Business Bureau and the Foundation Repair Association.
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