In order to meet desired seismic performances, it is increasingly evident that engineers require reliable methods for the estimation of seismic demands on both structural and non-structural elements. To this end, current design codes incorporate simplified methods for the prediction of acceleration demands on secondary structural and non-structural elements for buildings with fixed bases. However, no guidance is currently provided as to how to estimate the seismic demand on nonstructural elements in base isolated structures. In such structures, large floor accelerations may still be recorded, particularly in the case of higher mode interactions or horizontal-vertical coupling effects. In all cases, determining the seismic demand on non-structural elements is necessary in order to be able to perform a rational design of those elements, and to be able to effectively control their seismic response. In order to take a step towards the formation of accurate yet simplified methods of predicting peak floor accelerations and floor spectra in base isolated structures, this analytical work examines the response of a number of base isolated case study structures subjected to a series of ground motions of varying intensity. The results of the non-linear time history analyses are used to identify the factors that appear to affect the shape and intensity of acceleration demands on secondary structural and non-structural elements.