Timber is considered as an elastic-brittle material.
Dependence of timber properties on time and environment conditions is neglected. The presented statistical analysis of MOE is based on experimental data. An original method for determination of the MOE function on the basis of a measured deflection curve has been developed. The variability of bending strength of timber beams has been studied with help of a weak-zone model. Assuming a marked Poisson random field as a probabilistic model of bending strength, analytical solutions have been derived for a number of particular problems.