A connection system between adjacent sandwich panels for use in building floor rehabilitation, consisting of an adhesively (epoxy) bonded Z-joint, is proposed and studied. Experimental and numerical investigations were carried out to assess the joints' behaviour under vertical loads, their effect on the overall mechanical response of the sandwich floor panels, and the stress distributions within the various panel components. Their behaviour along the transverse and longitudinal (main span) directions was studied for panels made of glass-fibre reinforced polymer (GFRP) faces and two types of cores: polyurethane (PUR) foam and balsa wood. The joints' failure along the transverse direction occurred in the GFRP elements due to excessive through-thickness tensile stresses failure in the adhesive layer was not observed. In the longitudinal direction, joint failure did not occur. The developed FE models were able to simulate the behaviour of the connections and jointed panels, providing reasonably accurate predictions for the deformations and failure modes experimentally observed. The joints significantly increased the panels' shear stiffness, but showed limited influence on their bending stiffness. Although the flexural stiffness of the PUR foam and balsa wood cored panels was similar, the balsa wood core absorbed a significantly higher portion of shear force. (C) 2015 Elsevier Ltd. All rights reserved.