It is well known that different vertical density profiles influence physical and mechanical properties of particleboards. The purpose of this research was to determine how to choose the optimum particleboard for construction purposes depending on the physical and mechanical properties. Five series of three-layer particleboards were made. They were mostly different in density and thickness. The density of individual layers was increased and mixed chips (beech and spruce) were used. They were taped over with a urea-formaldehyde adhesive (UF). The mat was pressed at a temperature of 190°C and specific pressure of 9 N/mm2 to reach nominal thickness of 16 mm. The boards were then cooled down and stored at a temperature of 20%2°C and a relative humidity of 65%5 %. The panel A was the control panel (conventional industrial three-layer particleboard). Other boards were made with differently: chips of the outer layer were added to the inner layer or vice versa. With relatively small additions in the panels B and D (A + cca. 10%), we achieved great increase in physical and mechanical properties compared to the control panel A. In the plates C (A + 21.4 %) and E (A + 25.8 %) we exaggerated more. The panel C, where we added 60 % of CL to SL, resulted in a uniform composition. Due to large particles in the outer layer, reverse deformation of particles (spring back effect) at the end of compression (at the opening of the press) occurred. However, the board C achieved very good results in shear strength and shear strength along the edge. A similar spring back effect also occurred in panel E, which had the greatest number of particles added in relation to the control plate. At the board E we exaggerated the most, which led to a collapse after opening the press. The plate was damaged (stratified) and reached similar results to the control panel, and some tests could not even be performed. We can conclude that we have managed to define the maximum amount of particles which can still be added to improve the plate. The quantity is in the range of the plates D and C. But now we can see how a relatively small change affects the final properties.