The Pressed Piling method of foundation repair evolved in the 1980s in an effort to reduce the cost of repairing foundations. It was successful in reducing repair costs for thousands of homeowners in the southern part of the United States. However, it had a much greater impact on raising the profit margins of the foundation repair companies by lowering the installation costs. Unfortunately, it was, and still is, a poor long term solution for failing foundations. It has been widely tested for over 20 years and the pressed piling method of foundation repair has proven to have serious drawbacks.
The cause of almost all foundation problems in the southern United States is the presence of expansive soils. Foundations rest on top of these soils and therefore provide the ultimate support for the foundation. The problem is that portions of the soil under the foundation will absorb large volumes of water and swell. This creates a “lifting” effect on one portion of the foundation and causes damage throughout the building structure. Similarly, when a portion of the soil under the foundation loses a significant amount of water due to evaporation or tree roots, the foundation will lose its underlying support and “fall” or “cave in.” Typically these problem areas are around the perimeter of the foundation because the moisture content of the soil in the center portion of the foundation remains relatively stable.
The pressed piling method utilizes a series of precast concrete cylinders that are driven into the soil using the weight of the commercial building or home. This is the first major disadvantage of this method. The driven piles will reach a point where they can not be driven any further with the weight of the building structure. This is called the refusal point and all attempts of driving piles deeper should cease immediately. The force required to drive the piles past the refusal point is greater than the force needed to lift the foundation into the air. If the work crew continues to attempt to drive piles deeper they will only succeed in raising a portion of the foundation further into the air. This is a critical point and the work crew could potentially cause severe damage to the foundation if they continue.
Another major disadvantage of pressed piling is that there is no method to determine if the piles have been driven into a straight and vertical column. Past history has shown that often times the piles will hit a rock, tree root, or other obstruction and become misaligned. Other times the driven piles will simply “wander” off at an angle. And other times the NON reinforced pressed piles will break and cause misalignment. If the pressed piles are misaligned then their ability to provide support to the foundation is essentially “zero.”
Because the pressed piling method of foundation repair was designed to be a low cost alternative, a soil test, or review of a soil test by an engineer, is a rarity. Therefore the repair company has NO idea how deep they must drive the piles to reach stable soil or bedrock. If the driven piles do not reach stable soil or bedrock then they have little or no value as a long term solution.
The pressed piles are not connected in any manner and they are subject to the lateral and vertical forces of soil movement which can cause vertical and horizontal misalignment of the piles. Expansive soils will repeatedly shrink and swell during a single year. After several years the unconnected piles can easily become horizontally misaligned or lose their vertical integrity. When that happens, the column of piles will lose its ability to support the foundation.
In sum, the pressed piling method of foundation repair is flawed with significant disadvantages. Many commercial and residential property owners have selected this low cost method of repair and later discovered its disadvantages. Virtually all structural engineers will suggest that this method be avoided. The best “insurance” is to select an experienced foundation repair company with many years of history and demand a warranty or lifetime service agreement that does NOT curtail the legal rights of the property owner.
Author Resource:
Martin Dawson is the co-founder (1984) of Dawson Foundation Repair. He is a leading authority in Texas and other southern states on repairing failed commercial and home foundations using the thoroughly researched drilled Bell Bottom Pier method. http://www.DawsonFoundationRepair.com/
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