The aim of this study was to investigate the impact of impregnation with boron compounds borax (Bx), boric acid (Bx), Bx + Ba (wt : wt 50 : 50%), Imersol-aqua (Ia) and Timbercare-aqua (Ta) on combustion properties of the laminated veneer lumber (LVL) obtained from European oak (Quercus petrosa Liebl.) and Lombardy poplar (Populus nigra L.) woods, impregnated with boron compounds, Imersol-Aqua, and Timbercare-Aqua according to ASTM D 1413-76-99 and directions of the manufacturer. The LVL samples were prepared in the form of five layers, of 3-mm thickness from the oak and poplar veneers according to TS EN 386. Combustion properties of the LVL test samples were determined according to ASTM D 160-50. Considering the interaction of combustion type and impregnation materials, the highest flame source combustion (FSC) and without flame source combustion (WFSC) temperatures were found in control test samples, but the lowest values in samples impregnated with Bx and Ia solutions. Consequently, borax in FSC and Imersol-Aqua in WFSC showed a decreasing impact on combustion properties of the LVL, produced combination of European oak and Lombardy poplar veneers, and bonded with Desmodur-VTKA. In consequence, the LVL impregnated with borax and Imersol-Aqua could be recommended as a flame retardance construction material where required. © 2007 Wiley Periodicals, Inc.