In multistory work, the shoring which supports freshly placed concrete is necessarily
supported by lower floors which may not yet have attained their full strength, and which may not have been designed to carry loads as great as those imposed during construction.
Construction loads may exceed design loads by an appreciable amount.
Therefore shoring must be provided for enough floors to develop the needed capacity to
support the imposed loads without excessive stress or deflection. Whether permanent shores
or reshores are used at the several required lower floor levels depends on job plans for reused
of materials as well as the rate of strength gain in the structure.