Timber Category / Grades
The load carrying capacity of wood is affected by the quality of the used Lumber. Different grades have been established to classify Lumber.
Old grades were S7, S10, MS10, MS13 etc. S for manual classification, MS for automatic (machine) classification. Hardwood was called LS, glue laminated timber - BS.
Modern grades have an C for coniferous wood, D for hardwood and GL for glue laminated timber. The higher the number is, the better is the quality. Hardwood is better than coniferous wood.
From where do i get the grade
Normally the seller of the wood should be able to tell you the sorting grade. If not you can choose the standard value for nice coniferous wood, which is C24, If the Quality is not too good and you want to stay on the safe side choose C16.
For Glue Laminated Timber choose GL24 which is on the safe side. If you get a sorting specifictaion for your glue lamineted timber it is not relavent for these calculations, if the last character is an c or an h (GL24c = GL24h).