“The vast majority of home foundation repairs in Texas are NOT designed to succeed. And if they don’t succeed then they are a failure,” stated Martin Dawson of Dawson Foundation Repair in Houston, Texas. “However they do succeed in putting a lot of profit into the pockets of the foundation repair contractors.”
For the past 37 years operating his foundation repair company Mr. Dawson has been highly critical of the most common foundation repair method used in Texas. It is called the “Pushed Pile” method and this method offers quick and relatively easy installation. It is a process where the workers use hydraulic jacks to push concrete piles into the ground. The home’s concrete slab foundation, its weight and strength, is used as the fulcrum to drive piles into the soil. According to Mr. Dawson this repair method is very common because of its lower cost. But its lower cost is directly related to its lower quality. A-1 Engineering states that this foundation repair method is “temporary” and “useless”.
Yes. A well-built house can have a lifespan of 200 years or more. But houses built on top of clay soils can have shorter lifespans because of the constant expansion and contraction of the clay soils. This is know as upheaval and settlement. Clay soils are the primary enemy of home foundations – both concrete slabs and pier & beam. It makes sense to preserve the value of the house for the present and the future.
“There are about a dozen reasons I can list for you but in my mind there are four primary reasons pushed pile foundation repair methods fail and any one of the four can doom a foundation repair job,” stated Mr. Dawson. The four factors cited by Mr. Dawson are:
- Lack of Vertical Confirmation
- Small Footprint
- Only a Factor of Safety of 1
- Broken Cylinders can not be Seen
Lack of Vertical Confirmation
There is no method to determine if the concrete cylinders are installed in a vertical column. Many times they will hit a tree root or rock in the soil and skew-off in an angle. When that happens the load bearing capacity of the column of piles is lost. The bottom line is that this repair method is based on HOPE. The contractor hopes his workers, and maybe divine intervention, have installed 10 or 15 concrete piles in a vertical column.
The typical concrete cylinder used for pushed piles is 6 inches in diameter. That provides a total surface area (footprint) of a little more than 28 square inches for stability and load bearing. The competing foundation repair method, Bell Bottom Piers, has a footprint of 380 square inches and can support 5 to 10 times the weight of pushed piles.
Only a Factor of Safety of 1
Factor of Safety is an engineering term (numerical value) that describes the load capacity of of a system. Basically, the factor of safety is how much stronger the system is than it usually needs to be for an intended load. The minimum is 1 because any number less than 1 means the the structure or component is not viable, that is, it can not support the load or stress placed upon it. A Factor of Safety of 1 means that a structure will fail when the load / weight exceeds the design load. That means that when push piles are installed they will fail if 1) the skin friction of the cylinders with the soil is reduced by water intrusion, or 2) the weight of the house and its contents increases (for example, car in a garage).
Broken Cylinders Can Not Be Seen
It is a known fact that the concrete cylinders used in the pushed pile method can and do crack and fracture under the stress of the hydraulic jack. Those cylinders that are in the soil and fracture after another pile has been placed above it will never be discovered. In these cases the column of pushed piles has virtually no ability to support the weight of the house. In addition, the columns on either side of the flawed column will not be able to support the additional weight because their Factor of Safety is 1, that is, they can not support any additional weight.
Foundation repair is expensive because all of the installation work must be done under the foundation of the house. Installing multiple 10 or 15 foot columns of concrete under a concrete slab foundation is a challenge. This process is called Underpinning, which is providing additional support to the existing slab foundation and additional resistance to soil movement. The underpinning will support the weight of the concrete slab and house.
Martin Dawson is the owner of Dawson Foundation Repair and has been installing Bell Bottom Piers under residential homes and commercial properties in Texas since 1984. He is a staunch advocate of the Bell Bottom Pier method of foundation repair because it is Proven, Time-Tested, and Permanent.