Dimensional variation in sheet metal assembly affects product fit and functionality. To predict the variation of assembled products, variation simulation analysis has been gradually adopted in the early design stage. However, variation simulation based on rigid body assumptions usually results in over estimation of the assembly variation. In this paper, we propose an offset beam element model for predicting the assembly variation of deformable sheet metal parts joined by resistance spot welding. The purpose of using the offset beam element is to include the shear effect provided by resistance spot weld nuggets that cannot be captured by the conventional beam element. The offset element is then applied to predict sheet metal assembly variation for one-dimensional (1D) models extracted from industrial practice. The first example evaluates the effects of sheet metal thicknesses on assembly variation. The second example shows how the assembly sequence affects assembly variation. These models provide interesting insights into the mechanisms of variation stackup and will lead to the understanding of more complex sheet metal assemblies.