While the ultimate purpose of the excavation does not define the shoring which may be required to protect it, the type of shoring used often defines the type of excavation which may be undertaken. The life cycle of an excavation has a large input into the decision as to which method is used. Excavations which will only be open for a very short period of time are often shored with very different methods than might be used for longer periods of time. In fact the length of time that an excavation is open may determine if it is shored at all.

Excavations are shored for a variety of reasons. They may be shored to limit the amount of overexcavation required when sloping the sides of the cut. They may be shored to protect the personnel who enter and work within the excavation. Shoring may be placed to protect adjacent property such as buildings, utilities or property for which no easement is available. Shoring also may be installed to minimize the excavation and therefore maximize the usable property around the excavation. In doing so, close access for hoisting into the excavation and storage of materials slated to be used in the excavation can be enhanced.