COMPARISON OF FOUR METHODS FOR NATURAL DURABILITY CLASSIFICATION AFTER 2,5 YEARS

Per Otto FLÆTE
Researcher - Norwegian Forest and Landscape Institute
Address: PO. Box 115, 1431 Ås, Norway
Tel: 0047 64948000. Fax: 0047 64948001. E mail: Per.Otto.Flate@skogoglandskap.no

Gry ALFREDSEN
Researcher - Norwegian Forest and Landscape Institute
Address: PO. Box 115, 1431 Ås, Norway
Tel: 0047 64948000. Fax: 0047 64948001. E mail: Gry.Alfredsen@skogoglandskap.no

Fred EVANS
Researcher - Norsk Treteknisk Institutt, Postboks 113 Blindern, 0314 Oslo, Norway
Tel: 0047 64948000. Fax: 0047 64948001. E mail: Fred.Evans@treteknisk.no

Abstract: In Norway exterior wood structures have traditionally nearly exclusively been made of treated and untreated Picea abies and Pinus sylvestris. In recent years there has been a tendency that other tree species, like various domestic hardwoods and imported species have been used in exterior above ground applications, often unfinished. For several wood species, especially hardwoods, information regarding the durability in use class 3 is lacking. The main objective of this paper is to evaluate natural durability of Norwegian wood species for above ground applications comparing two non-standard above ground tests with the European standard tests for soil contact (EN 252) and lab performance against basidiomycetes (EN 113).
The European standard tests EN 113 and EN 252 gave quite similar results, and they also corresponded well with the natural durability classification in EN 350-2. The two non-standard above ground tests differed to some extend from EN 113, EN 252 and EN 350-2. The results indicate that natural durability classification for one single wood species can change depending on use class. However, the field trials need a longer period of time before a final classification can be performed. Four species not included in EN 350-2 were classified in this study: Juniperus communis (1), Salix caprea (5), Sorbus aucuparia (5) and Populus tremula (5).

Key words: method comparison, natural durability, Norwegian wood species, test methods.

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