Repair Off-Center Footings during Building Construction
Contractors sometimes encounter challenges in positioning footings accurately within a trench, resulting in foundation walls that are not centered on the footings (as shown in Figure 1). However, it is crucial to ensure that the foundation wall is correctly positioned to adequately support the house. Despite these difficulties, contractors may find that the foundation wall has been placed off-center on the footing.
The incorrect placement of the footing in Figure 1 has resulted in the foundation wall being off-center. This may not pose a problem if the soil is strong, but if the footing is on weaker soil, it is recommended to fix it. In good bearing soil, this foundation issue is not a major concern for loads typically associated with a simple wood frame house. The full width of the footing may not be necessary to support the loads, and the wall can be constructed along the edge of the footing and still provide sufficient support. However, if the wall extends beyond the edge of the footing on the side or end, it can generate rotational forces that the footing is not designed to handle. In such cases, the involvement of an engineer may be necessary. The risk is even greater if the soil is relatively soft.
In cases where the soil is strong, if there is a mistake in the footing layout, it can be corrected by placing gravel to provide support to the wall. On the other hand, in weaker soils, it is recommended to cast an augmented footing alongside the existing footing. This new footing is connected to the existing footing using dowels that are epoxied into the side of the existing footing. It’s important to fill any notches in the footing and cut off any existing steel dowels that will not properly support the wall.
For soils with high bearing capacity, typically greater than 4,000 pounds per square foot (psf), the recommended approach is to excavate next to the footing and underneath it, and then fill the space with compacted large gravel. This should provide sufficient support for the wall.
However, in weaker soils, the existing footing itself needs to be augmented with steel and concrete. Similar to the previous approach, excavation is still required, but instead of filling it with gravel, steel dowels are drilled into the side of the footing and then epoxied into place. Concrete is then placed to extend the footing out to the proper width, ensuring adequate support for the wall.