What type of foundation is recommended for a five-story addition?

A shallow foundation with cantilever footings is often recommended for a five-story addition when the soil conditions are adequate to support the structure. This type of foundation is typically used in situations where the building loads can be appropriately supported by the soil near the surface.

Shallow foundations can be advantageous in terms of cost and construction time, especially when compared to deep foundations. Cantilever footings extend beyond the foundation wall, providing additional structural support and helping to reduce the risk of settling or shifting as loads are distributed across a wider area. This configuration is particularly useful in minimizing lateral forces acting on the structure.

By employing a shallow foundation with cantilever footings, designers can also facilitate easier integration of the new addition with the existing structure, thereby maintaining a cohesive design. It’s important that the underlying soil is capable of bearing the loads from the additional stories; otherwise, a different foundation solution may be necessary.