Repairing sunken foundations can be a tricky job.
If they are built on loose soil or expansive clay, concrete slab foundations can potentially sink into the earth and eventually start to crack or fail. Builders have different approaches they use to tackle this problem, but one common technique involves the use of steel piers to restore the building and its foundation to their original elevation. Does this Spark an idea?
Problems
Changes in moisture can cause some soils to swell or contract to a significant extent. If the soil beneath a foundation is unstable, it may cause the concrete atop it to move. These problems occur not only with slab foundations but also with pier and beam types as well. Inevitably, some parts of the soil change or shift more than others, and this so-called differential settling can sometimes damage the foundation badly.
Benefits
Piers are only one of the techniques builders use to fix sunken foundations, but they have a number of advantages. They don't require destroying the yard or dragging in heavy equipment, nor do you need to cease using the building. The necessary equipment is relatively light and can be installed even while the building remains in use. Piers are also cheap when compared with the cost of replacing the foundation altogether.
Types
There are two types of pier systems: push piers and helical piers. A push pier has multiple sections that are driven down through the soil by a hydraulic ram. Helical piers, by contrast, feature a helical section with a steel shaft attached. The helical pier is forced into the ground by turning it with a hydraulic torque motor. Both types are driven downward until they encounter rock that can serve as a support.
Function
When builders repair a foundation, they insert multiple piers that reach down to the rock layer below the soil. These piers provide a firm support for hydraulic jacks, which raise the foundation upward until it reaches the original level. At this point, the builders can attach the piers directly to wall brackets and thereby lock the building in place so it will not sink back into the soil again.
Tags: slab foundations, sunken foundations
