Birch plywood has a wide range of applications for interior and exterior use. The demand for plywood with improved fire protection properties and good visual appearance is increasing year by year. The impregnation at high pressure of the whole plywood panels is one of the options to achieve it. The aim of this study was to develop good visual looking birch plywood product for interior design purposes as well evaluate different influencing factors to reaction to fire properties of fire-retardant treated birch plywood. This study consists of three parts. At the first stage, high pressure industrially impregnated plywood properties were studied by two influencing factors – distribution of fire retardant in plywood panel plane and sanding process influence on reaction to fire performance of product. At the second stage, seven different industrial finishing systems were selected for covering high-pressure impregnated birch plywood and their effect on fire reaction performance was studied. In addition, two surface coating systems were studied on standard birch plywood substrate. At the third stage, intumescent coating consumption effect on reaction to fire performance was studied. The reaction to fire performance of birch plywood was evaluated by performing a flammability test using the Single Burning Item test according to EN 13823:2010. It was found that high pressure impregnation of plywood cannot ensure even saturation of fire retardant throughout the sheet, which significantly affects the fire performance of product. The impact of different finishing materials to reaction to fire performance has been described by the results of this research.

In the market of the Latvia different wood surface coating materials suitable for use in outdoor conditions are offered, but available information on the efficiency of these against direct water exposure is insufficient. For structural timber building elements, such as glued laminated timber (GLT), the surface coating should be applied taking into account technological, visual or colour changes (ISO 7724:1984) and – last, but not least – economic aspects are considered. Wood surfaces coated with coating materials, such as varnishes, paints, etc. can stabilize some properties such as movement of moisture content, dimensional changes and attack by microorganisms and fungi. The changes in the moisture content of timber may influence such important parameters as mechanical properties and the total life time of the structural timber elements. A study has been conducted with the aim of assessing the efficiency of coating materials used for wood protection against water absorption. In this study, six different commercial coating products used for the treatment of spruce (Picea Abies L. Karst.) and pine (Pinus Sylvestris L.) samples were tested. The efficiency of different coating substances was assessed using two modified test methods according to the standards EN 382-2 (1994) and EN 927-5 (2006), determining the surface water absorption after immersion in water for 24 h and the dynamics of water absorption of the glued laminated timber for 696 h kept in water. As a result of the study, it has been ascertained that organic solvent-based commercial coating products are more efficient against short-term and long-term wood water absorption compared to oil-based coating materials.