This part of EN 351 provides guidance on the general procedures used in obtaining samples of preservative-treated wood to determine the penetration and retention of wood preservative.This part of EN 351 is applicable for the production of preservative-treated solid wood, including glued laminated timber, suitable for use in those service conditions defined by the use classes in EN 335-1. However, the sampling guidance provided within this part of EN 351 may be applied for the subsequent examination of treated wood in service.