Comparison of the Spanish visual strength grading standard for structural sawn timber (UNE 56544) with the German one (DIN 4074) for Scots pine (Pinus sylvestris L.) from Germany

The results of visual grading according to the Spanish (UNE 56544 2003) and German standards (DIN 4074 2003) for a sample of more than 200 sawn timber pieces of Scots pine from Germany are shown in this paper. The cross sections of the pieces were 40×180, 60×120, 60×180, 60×240, and 80 × 180 mm 2 . The aim of this work is to compare the grading performance of both standards and to discover which criteria are the most relevant for determining the subsequent grading process. According to the results the Spanish standard has a lower grading performance than the German one, except for the highest strength class (C30) for which it is practically the same. A new procedure for the assessment of knot size is proposed with the aim of including it in the Spanish standard, giving better grading performance and making it easier to apply.