The percentage of wooden buildings damaged or even lost due to the lack or insufficient technical measures for their preservation is growing every year. This fact makes it mandatory to treat the surface of wood building materials with protective and decorative agents. Within the framework of this study, a multifunctional protective composition for wood was developed that can increase its physical and mechanical properties. Modification of the wood surface with organomineral compositions leads to an increase in its density, hardness and strength. The hardness of the treated wood is 24% higher and the compressive strength along the fiber is 20% higher than that of untreated wood. After treatment, the surface of the wood darkened and slightly yellowed, which does not prevent its use in the construction and reconstruction of buildings. The results of measuring the color coordinates of the surface of the modified samples indicate the stability and durability of the developed protective coating even after 4 months of exposure to atmospheric conditions. Judging by the slight return of the color coordinates of the treated wood back to values of the original wood, it can be concluded that the composition is partially washed out.