Visual and machine grading of larch (Larix decidua Mill.) structural timber from the Italian Alps

The present paper focuses on the main results of an inter-regional project (Bois-lab) aimed at determining the settings of various machines for grading larch (Larix decidua Mill.) timber from Italian and French Alps, that can now be graded for structural use and CE marked according to EN 14081-1. In particular it reports the differences registered between visual and machine grading on 261 larch beams. Visual grading was made according to the Italian national standard UNI 11035-1,2 while machine grading was performed using various devices. Finally the wooden material was subjected to laboratory testing according to EN 408. The results showed that machine grading yields are significantly higher, especially due to the reduced number of rejected elements. The paper also evaluates the flexibility and potential of the above methods taking into account different combinations of strength classes in terms of output.