It is now widely recognized that the performance of non-structural elements is crucial to the performance of building systems during earthquakes. Field surveys and experimental studies have shown that light steel or timber framed plasterboard partition walls are particularly vulnerable. The objective of this study is to investigate the seismic performance of a novel seismic gap partition system with angled return walls under quasi-static cyclic loading applied obliquely and to investigate the benefits of using acrylic gap-filler in the seismic gaps. Two specimens were tested: a steel stud specimen and a timber stud specimen. Observed drift capacities were significantly greater than traditional plasterboard partition systems. Equations were used to predict the drift at which damage state 1 (DS1) and damage state 2 (DS2) would initiate. The equation used to estimate the drift at the onset of DS1 accurately predicted the onset of plaster cracking but overestimated the drift at which the gap filling material was damaged. The equation used to predict the onset of DS2 provided a lower bound for both specimens and also when used to predict results of previous experimental tests on seismic gap systems. The gap-filling material reduced the drift at the onset of DS1, however, it had a beneficial effect on the re-centring behaviour of the linings. Out-of-plane displacements and return wall configuration did not appear to significantly impact the onset of plaster cracking in the specimens.