Certification according to SANS & Grades
The Czech Timber Institute has prepared a comparison on the European Spruce and various types of Pine which grow in South Africa (Information provided by SATAS). The European Spruce supplied by Herrmann & Vogel and sold by Universal Plywoods is certified as Grade 5 according to SANS, however the only value which pushes the spruce down to Grade 5 is the “Compression perpendicular to grain”. All other values and characteristics will allow the Spruce to be certified as Grade 7 or even 10 according to SANS.
We have asked Static Engineer Lukas Krbec how to deal with lower value of Compression perpendicular to grain. Lukas says that a "slight disadvantage of lower local load-bearing capacity of the wood element can be eliminated by suitable local modification of the construction detail. One of the possibilities is the use of reinforcing screws, which ensure the distribution of local force along the entire height of the cross-section. There are, of course, other methods and the task of the designer/engineer is to choose the best solution for a specific case."
Timber as natural material has several specifics and at the same time offers many advantages which motivate architects, engineers and investors to build sustainably.