AbstractThe objective of this research was to investigate the effects of impregnation chemicals on the combustion properties of 3-ply laminated veneer lumber (LVL) made of Oak (Quercus petraea subsp. İberica) and Poplar (Populus tremula L.). For this purpose, oak wood was used as the outer ply and poplar used for the core ply in LVL. Borax (BX), boric acid (BA), borax+boric acid (BX+BA), and di-ammonium phosphate (DAP) were used as impregnation chemicals, and urea formaldehyde (UF), phenol formaldehyde (PF), and melamine-urea-formaldehyde (MUF) adhesives as bonding agent were used to produce LVLs. The vacuum – pressure method was used for the impregnation process. The combustion test was performed according to the procedure defined in the ASTM–E 69 standards, and during the test the mass reduction, temperature, and released gas (CO, O2) were determined for each 30 seconds. As a result, di-ammonium phosphate was found to be the most successful fire retardant chemical in LVL with MUF adhesive. LVL produced from a combination of oak and poplar veneers with MUF adhesive and impregnated with DAP can be recommended to be used as a fire resistant building material where required.