This European Standard specifies a method of test for wood preservatives that are intended for use under a surface coating in timber to be exposed to the weather and out of contact with the ground (Use Class 3, EN 335-1). The main objective of the test is to evaluate the relative effectiveness of the preservative applied. Effectiveness is evaluated relative to a reference material. Jointed samples (L-joints) are treated, assembled, coated and placed out of contact with the ground and exposed to the normal environmental and ecological factors which affect coated wood so exposed in practice. However, by comparing the results obtained for the test preservative with those obtained with the reference material and with those for untreated, control L-joints, the relative protective effectiveness of the preservative under test can be evaluated. Compared to EN 330:1993, the scope of the standard clarifies that the effectiveness is evaluated to a reference preservative. The grading system for the assessment of decay has been modified in Table1 and modifications have been made to the duration (Clause 14) and validity (Clause 15) of the test. In Annex B, information has been added that the reference wood preservatives partly may only be used for research purposes in accordance with the Biocidal Products Regulations. An informative Annex D giving guidelines on environmental and health precautions has been added. The committee responsible for this standard is NA 042-03-06 AA "Spiegelausschuss zu CEN/TC 38 und ISO/TC 165/SC 1 Dauerhaftigkeit von Holz und Holzprodukten" ("Mirror committee for CEN/TC 38 and ISO/TC 165/SC 1 Durability of wood and wood products") at DIN.