Current paper deals with numerical analysis and optimisation of the mechanical and thermal behaviour of rib-stiffened sandwich panels with plywood and PU foam core constituents. The effect of the skin and rib thicknesses and core density on mechanical and thermal properties has been analysed. Sandwich panel stiffness and of effective thermal conductivity were acquired by means of numerical models in ANSYS software. Parametrical optimisation of the cross section dimensions and material properties was performed to found the best trade-off between stiffness, structural weight and thermal properties. Comparing optimised sandwich structures with tradition plywood boards it is possible to found equivalent stiffness sandwich panels with weight reduction up to 35 % and effective thermal conductivity of 0.029 W/m*k (reference to 0.12 for solid plywood board). In addition Pareto optimality front between structure weight and stiffness (comparing to solid plywood) and effective thermal conductivity has been constructed.