The structural system for most houses is based on concrete bearing walls and steel posts in the basement. Then structural system of timber joists, bearing walls, timber posts in the main floor. Finally, system of trusses is installed to cover the roof. Therefore, the concrete bearing walls in the basement concrete wall is of extreme importance as they transfer the loads from the top of the roof trusses to the foundations. Figure 1 illustrates some of the basement cracks that you can notice.
Figure 1. SEvere cracks due to concrete basement bowing.
The causes of cracks whether in basement concrete walls or slab on grade in the flooring of the basement are attributed to many reasons. The most common factor for all these cracks is the soil pressure. This soil pressure could be in horizontal direction as the case of the vertical concrete basement wall. This in general will cause horizontal crack as shown in Figure 2.
Figure 2. Horizontal cracks due to horizontal soil pressure on basement concrete wall.
Figure 3. Diagonal Cracks due to differential settlement of basement wall foundation.
The solutions of horizontal cracks could be in many forms. First, for slight cracks and minor bows, replacement of the exterior existing soil with gravel layer is considered to be a cost effective solution to avoid further crack propagation in the concrete wall due to the exterior soil pressure. The contractor should install a drainage pipe underneath the gravel layer to ensure that any rain or snow will be drained to the weeping tiles at the slab on grade level of the basement. This is illustrated in Figure 4.
Figure 4. Recommended solution for the slightly bowed concrete basement wall.
Figure 5. Recommended solution for the medium bowed concrete basement wall
Figure 6. Tiebacks for severely bowed concrete basement wall
Consult with your engineer if you observe any cracks in your concrete basement wall. Save your assets by early reporting any incidences. Time is not in your benefit. Solving the problem early saves you money and hassle.
The information in this article is intended to provide a big picture about the available solutions for crack foundations. No body is allowed to use this information in their respective properties without the engineer approval.