In this study, the effects of impregnation materials - di-ammonium phosphate, aluminium sulphate, potassium carbonate, calcium chloride, zinc chloride - on combustion properties of 3-ply laminated veneer lumbers (LVL) produced from oak (Quercus robur L.) bound by phenol -formaldehyde (PF), or poly(vinyl acetate) (PVAc) have been investigated. The pressure-vacuum method was used for the impregnation process. Combustion test was performed according to the procedure of ASTM-E 69 standards. According to the test results, zinc chloride was found to be the most successful fire retardant chemical in LVL with PF adhesive. Since zinc chloride diminishes combustion, it is possible to advise the use of LVL produced from oak with PF adhesive and impregnated with zinc chloride as a fire retardant building material where required. (C) Koninklijke Brill NV, Leiden, 2009