The demand for engineering wood products ( such as oriented strand board, glulam, and laminated veneer lumber [ LVL]) has increased due to a constant increase in the global population. The processes of combustion are extremely complicated, principally because the wood has a complex physical and chemical composition. The burning of hydrocarbons is frequently chaotic. In this study, the effects of impregnation chemicals, namely diammonium phosphate, aluminum sulfate, potassium carbonate, calcium chloride, and zinc chloride, on the combustion properties of three- ply LVLs has been investigated. The LVL used in this study was made of scotch pine ( Pinus sylvestris L) by using phenol formaldehyde ( PF) and poly( vinyl acetate) ( PVAc) as adhesives. The pressure- vacuum method was used for impregnation process. The combustion test was performed according to the procedure defined in the ASTM- E 69 standard. As a result; diammonium phosphate was found to be the most effective fire- retardant chemical in LVL with PF and PVAc adhesives. Because it diminishes combustion the most, LVL made of scotch pine with PF or PVAc adhesives by using pressure- vacuum method and impregnated with diammonium phosphate, can be recommended as a fire- resistant building material where required.