EVstudio is asked quite frequently to perform structural evaluations of cracked foundation walls. These cracks are often due to settlement. Modern design philosophy (and most geotechnical reports) calls for the original structural engineer to design foundation walls to clear span ten to fifteen feet to account for soft patches of bearing soil or soils that may be become saturated and hydro-consolidate (shrink in volume when wet). Older homes are more susceptible to damage because they were typically not designed with this in mind. This is not to say they were designed poorly, there were just different design philosophies and industry standards at the time they were constructed.
How a resistance pier works is quite simple. First, a steel bracket is fastened to your foundation, typically at the footing. Then a hydraulic ram is installed on the bracket which drives a steel pier into the ground. Using the hydraulic forces in combination with the weight of the structure above, the steel pier is driven down through the softer soils (which are causing the settlement problem) until bedrock or suitably firm soils are reached. Once the pier reaches competent bearing, the foundation is stabilized and in some instances can even be raised back into a level position.
EVstudio works closely with Pinnacle Structural Services in the evaluation of foundation repairs utilizing the resistance piers as one of many considered solutions.
For more information on resistance piers please watch this informative video.