The scope of WG28 Performance Classification is expressed in this Technical Report: Guidance on the determination of end use performance of wood products: utilization and improvement of existing test methods to estimate service life, in order to give input to the harmonized product standards dealing with the durability requirement of the CPD and future Regulation (EU) No 305/2011 (The Construction Products Regulation CPR). This Technical Report brings together the evaluations and discussions to date that have occurred within CEN/TC38/WG28 Performance Classification. This technical report does not address panel products specifically.