Invention of light weight panel with a trade mark of Dendrolight is one of the most distinguished wood industry innovations of the last decade. At present three layers cellular wood panels have wide non structural application. The aim of the research is to evaluate the bending properties of three layer cellular wood panels for structural application. There were 8 specimens manufactured with thickness 136 or 152 mm, width 300 mm and length 2,500 mm of each of the six horizontal load bearing panel structural models. Scots pine (Pinus sylvestris L.) cellular wood and solid pine wood ribs were used as internal layer of the structural panels. Cellular wood core was placed in horizontal or vertical direction. Scots pine solid wood panels and birch plywood were used as top layer material. Applied glue was polivinilacetate Cascol 3353. The most common stress type in structural subflooring panels is bending; therefore, the influence of the cellular material orientation, ribs and top layer material on the sandwich type structural panel bending strength (MOR) and stiffness (MOE) were evaluated according to LVS EN 408:2011. Extra parameters like moisture content and apparent density were determined. Cellular wood in vertical direction can be used as raw material for structural panel production. Panels with solid timber external layers, with ribs and with vertical orientation of the cellular material showed the highest MOR (35.2 N mmE-2) and MOE (11,500 N mmE-2) values. The influence of the solid wood ribs on the bending properties is directly dependent on external layer material.

The influence of coniferous stand composition on the density of pine (Pinus sylvestris) and spruce (Picea abies) wood is considered in this work. Processing of a large quantitative material of wood cores with the use of the ANOVA and rank analysis made it possible to reveal the influence on the macrostructure of wood of the quantitative representation of pine and spruce in the stand. In the pine part of the stand, the correlation of the wood density with the zones of early and late xylem is weak or medium. There is no wood density correlation with the width of the annual ring for stands with different shares of pine. In pine-prevailing stands with a share of pine 80% – 100%, there is a weak but reliably straight relationship between wood density and the size of late wood zone and an inverse relationship with early zone of xylem. For forest stands with a smaller part of pine participation, the relationship between these indicators is medium and reliable. For spruce, we observe a close relationship between the density of xylem and the parameters of its macrostructure in all its variants of participation in mixed coniferous plantations. In most of the studied mixed stands, the density of wood in spruce is not significantly differentiated and more homogeneous.