Abstract Traditionally, loads specified for structural design correspond to maximum lifetime loads. These values are appropriate for lifetime (or “ultimate”) design in which the relative safe performance of the structural element or system is of concern. However, the use of these values for design for reduced reference periods (i.e., “shorter exposure periods”) may be excessively conservative. A number of design cases can be identified for which a 50-year reference period may not be appropriate, such as (1) buildings during construction, (2) temporary structures, and (3) serviceability. From a design standpoint, it may be most appropriate to provide modification factors to be used with existing (i.e., 50-year) design values. In this paper, one approach to determining appropriate design load values for design situations other than the full design-life is presented. This may be especially useful for the design of structures exposed to environmental loadings such as wind, snow and earthquake for relatively short exposure periods.