Both bench-footing and underpinning are common methods used to increase ceiling height in a building’s cellar. The major difference is how the excavation work is performed.
Underpinning is the process of excavating underneath the existing foundation and pouring new concrete underneath it. This is the preferred method for cavernous ceiling heights and amenities that require an extended foundation (e.g. swimming pools, elevators, etc.). Generally a successful procedure, legal issues can arise when adjoining walls are jointly shared with neighbors. In this case, licensing agreements must be settled before underpinning can begin, which can extend the length of the process.
Alternatively, bench-footing doesn’t require excavating underneath an existing foundation, which makes the method safer, quicker and less expensive. In this case, a foot step is created around the perimeter of the existing walls, resulting in a “bench” that’s incorporated into the proposed design. While less risk is involved in this method, it can severely reduce a property’s livable square footage, particularly in narrow brownstones.