Due to the highly demanding energy standards in Europe, thermal break elements, such as aerated autoclaved concrete (AAC), have become increasingly popular in modern residential buildings made of masonry cavity walls. Furthermore, a damp-proof course (DPC) layer is also used on top of the thermal break element to prevent water seeping and eventual entrapment due to capillary action. The presence of a combined AAC/DPC layer can therefore have an adverse effect on the global strength of a masonry wall, and in particular its shear resistance. This study aims at filling that knowledge gap through experimental investigations on traditional masonry walls and composite masonry walls, i.e. with an AAC and a DPC layer. The in-plane shear behavior is compared between both types of wall specimens using load-displacement curves and failure modes to highlight the structural influences of AAC and DPC. Existing analytical design approaches are also assessed based on the test results.