The goal of the performed experiments was to determine the strength, stiffness, and modulus of the elasticity of dowel, mortise and loose-tenon, and mortise and tenon L-type furniture joints under diagonal tension and compression loads. The specimens were constructed from Turkish beech (Fagus orientalis L.), white oak (Quercus alba), and white walnut (Juglans cinerea L.) and were assembled with a water-resistant PVA(C) adhesive. According to the obtained results, the highest stiffness/strength values were estimated in mortise and tenon joints constructed of white oak, whereas dowel joints constructed from Turkish beech showed the lowest stiffness/strength and deformability. The elasticity modulus of the experimental joints expressed their stiffness better than the stiffness coefficient. The accuracy of the developed elasticity modulus model of the examined joints was verified positively both by experimental studies and numerical calculations.