The highest quality, primarily for export or high-end joinery.
Decreasing quality levels based on the presence and size of defects. Grade 1 is typical for structural work, while Grade 4 is used for low-load tasks like crates or temporary structures. Technical Requirements gost 8486 57
Limits on the diameter, type (sound, loose, decayed), and number of knots per unit of length. The highest quality, primarily for export or high-end
Lumber must meet strict criteria regarding moisture, dimensions, and natural defects: The highest quality