Durability of wood and wood-based products - Testing and classification of the durability to biological agents of wood and wood-based materials

This European Standard gives guidance on methods for determining and classifying the durability of wood against biological wood-destroying agents, its permeability to water and its performance in use.
The methods can be applied either to individual wood species, batches of wood and wood-based materials.
This standard is not intended to test the efficacy of biocides.
The wood-destroying agents considered under in this standard are:
-   wood-destroying fungi (basidiomycete and soft-rot fungi);
-   beetles capable of attacking dry wood;
-   termites;
-   marine organisms.
Data on the biological durability of selected wood species considered of economic importance in European countries are presented in Annex B (informative), which also provides information relating to their geographical origin, density, sapwood width and treatability.
NOTE 1   The guidance on the durability classification appropriate for a particular use class is given in the EN 460 standard.
NOTE 2   Annex C (informative) provides a methodology allowing the classification of wood treatability
Wood durability is an important factor that influences service life of a wood product. This standard provides input to service life prediction of wood and wood-based products as it ranks durability against wood-destroying organisms of various wood species thereby allowing species of appropriate durability to be selected for a particular use class. It shall however be emphasized that the biological durability rating of wood species given in Annex B cannot be regarded as any guarantee of performance in service.
NOTE 3   There are many other factors influencing service life of a wood product, such as principles of good design, use conditions, climate, maintenance (…) and should be taken into consideration.

Dauerhaftigkeit von Holz und Holzprodukten - Prüfung und Klassifikation der Dauerhaftigkeit von Holz und Holzprodukten gegen biologischen Angriff

Diese Europäische Norm gibt eine Anleitung zu Verfahren für die Bestimmung und Klassifizierung der Dauerhaftigkeit von Holz und Holzprodukten gegen einen Befall durch biologische, Holz zerstörende Organismen.
Die Verfahren können sowohl bei einzelnen Holzarten, Holzlosen als auch bei verarbeiteten Holzprodukten angewendet werden; eingeschlossen sind thermisch behandeltes Holz, mit Holzschutzmitteln behandeltes Holz und modifiziertes Holz. Diese Norm ist jedoch nicht zur Prüfung der Wirksamkeit von Bioziden vorgesehen.
Zu den in dieser Norm betrachteten Holz zerstörenden Organismen zählen:
—   Holzfäule-Pilze (Basidiomyceten und Moderfäuleerreger);
—   Käfer, die trockenes Holz befallen können;
—   Termiten;
—   marine Organismen, die verbautes Holz befallen können.
Daten zur biologischen Dauerhaftigkeit ausgewählter Holzarten mit wirtschaftlicher Bedeutung in europäischen Ländern sind in Anhang B (informativ) dargestellt; darin enthalten sind auch Angaben zur geographischen Herkunft, Rohdichte, Splintholzbreite und Tränkbarkeit.
ANMERKUNG   Tränkbarkeit, Dauerhaftigkeit gegen Holz verfärbende Pilze, Wasserdurchlässigkeit und die Leistungsfähigkeit im Gebrauch von Holz und Holzprodukten sind ebenfalls wichtige Fragen. Da es jedoch keine genormten Verfahren gibt, die darauf abzielen, diese Faktoren zu bewerten und zu klassifizieren und/oder bis jetzt noch keine hinreichenden Erfahrungen vorliegen, gibt Anhang C (informativ) eine vorläufige Anleitung zur Klassifizierung der Tränkbarkeit von Holz mit wässrigen Holzschutzmitteln, Anhang D (informativ) zur Klassifizierung der Wasserdurchlässigkeit, Anhang E (informativ) zur Dauerhaftigkeit gegen Holz verfärbende Pilze und Anhang F (informativ) zur Klassifizierung der Leistungsfähigkeit.

Durabilité du bois et des matériaux dérivés du bois - Méthodes d'essai et de classification de la durabilité vis-à-vis des agents biologiques du bois et des matériaux dérivés du bois

Trajnost lesa in lesnih izdelkov - Preskušanje in razvrstitev trajnosti lesa in lesnih izdelkov proti biološkim agensom

Ta evropski standard podaja smernice za metode določevanja in razvrstitve trajnosti lesa proti biološkim agensom, ki uničujejo les, ter njegove propustnosti vode in učinkovitosti uporabe.
Metode se lahko uporabljajo za posamezne vrste lesa, šarže lesa in lesne izdelke.
Ta standard ni namenjen za preskušanje učinkovitosti biocidov.
Ta standard obravnava naslednje agense, ki uničujejo les:
– glive, ki uničujejo les (odprtotrosnice in glive, ki povzročajo mehko trohnenje);
– hrošči, ki lahko napadejo suh les;
– termiti;
– morski organizmi.
Podatki o biološki trajnosti izbranih vrst lesa, ki so v evropskih državah obravnavane kot pomembne, so navedeni v dodatku B (informativni), ki vključuje tudi informacije v zvezi z njihovim geografskim izvorom, gostoto, širino beljave in možnostmi impregnacije.
OPOMBA 1: Smernice glede razvrstitve trajnosti, ustrezne za posamezen razred uporabe, so podane v standardu EN 460.
OPOMBA 2: Dodatek C (informativni) določa metodologijo, ki omogoča razvrstitev možnosti impregnacije lesa.
Trajnost lesa je pomemben dejavnik, ki vpliva na življenjsko dobo lesnega izdelka. Ta standard vključuje podatke o predvideni življenjski dobi lesa in lesnih izdelkov, saj razvršča trajnost proti organizmom, ki uničujejo les, za različne vrste lesa, ter tako omogoča, da se za posamezen razred uporabe izberejo vrste z ustrezno trajnostjo. Vendar treba je poudariti, da ocena biološke trajnosti vrst lesa iz dodatka B ne pomeni nobenega jamstva za učinkovitost posameznih vrst lesa pri njihovi uporabi.
OPOMBA 3: Obstajajo številni drugi dejavniki, ki vplivajo na življenjsko dobo lesnega izdelka, kot so načela dobre zasnove, pogoji uporabe, podnebje, vzdrževanje (itd.), ki jih je treba upoštevati.

General Information

Status
Published
Public Enquiry End Date
08-Feb-2015
Publication Date
19-Jan-2017
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
31-Aug-2016
Due Date
05-Nov-2016
Completion Date
20-Jan-2017

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Trajnost lesa in lesnih izdelkov - Preskušanje in razvrstitev trajnosti lesa in lesnih izdelkov proti biološkim agensomDauerhaftigkeit von Holz und Holzprodukten - Prüfung und Klassifikation der Dauerhaftigkeit von Holz und Holzprodukten gegen biologischen AngriffDurabilité du bois et des matériaux dérivés du bois - Méthodes d'essai et de classification de la durabilité vis-à-vis des agents biologiques du bois et des matériaux dérivés du boisDurability of wood and wood-based products - Testing and classification of the durability to biological agents of wood and wood-based materials79.040Les, hlodovina in žagan lesWood, sawlogs and sawn timberICS:Ta slovenski standard je istoveten z:EN 350:2016SIST EN 350:2017en,fr,de01-februar-2017SIST EN 350:2017SLOVENSKI

STANDARDSIST EN 350-2:1995SIST EN 350-1:19951DGRPHãþD
SIST EN 350:2017
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 350
August
t r s x ICS
y {ä r v r Supersedes EN
u w ræ sã s { { vá EN
u w ræ tã s { { vEnglish Version

Durability of wood and woodæbased products æ Testing and classification of the durability to biological agents of wood and woodæbased materials Durabilité du bois et des matériaux dérivés du bois æ Méthodes d 5essai et de classification de la durabilité visæàævis des agents biologiques du bois et des matériaux dérivés du bois

Dauerhaftigkeit von Holz und Holzprodukten æ Prüfung und Klassifikation der Dauerhaftigkeit von Holz und Holzprodukten gegen biologischen Angriff This European Standard was approved by CEN on

s z June
t r s xä

egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä

translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey andUnited Kingdomä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels

t r s x CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN

u w rã t r s x ESIST EN 350:2017

EN 350:2016 (E) 2 Contents Page European foreword ....................................................................................................................................................... 4 1 Scope .................................................................................................................................................................... 5 2 Normative references .................................................................................................................................... 5 3 Terms and definitions ................................................................................................................................... 6 4 Sampling of wood and wood-based materials to be tested .............................................................. 8 4.1 Testing wood species ..................................................................................................................................... 8 4.1.1 General ................................................................................................................................................................ 8 4.1.2 Sampling logs .................................................................................................................................................... 8 4.1.3 Sampling sawn timber ................................................................................................................................... 9 4.2 Testing of sets of wood .................................................................................................................................. 9 4.3 Testing of wood-based materials .............................................................................................................. 9 5 General principles for testing and classification ................................................................................. 9 5.1 General principles for testing wood specimens ................................................................................... 9 5.2 General principles for the classification of durability .................................................................... 10 6 Test methods and classification system............................................................................................... 11 6.1 Durability to wood-destroying fungi ..................................................................................................... 11 6.1.1 General ............................................................................................................................................................. 11 6.1.2 Testing durability against basidiomycete and soft-rot fungi ....................................................... 12 6.2 Durability to larvae of dry wood-destroying beetles ...................................................................... 14 6.3 Durability to termites ................................................................................................................................. 14 6.4 Durability to marine organisms ............................................................................................................. 15 Annex A (informative)

Example of scheme for sampling heartwood ..................................................... 16 A.1 Logs ................................................................................................................................................................... 16 A.2 Central boards ............................................................................................................................................... 17 Annex B (informative)

Guide to biological durability and treatability of wood species marketed in Europe .................................................................................................................................... 18 B.1 General ............................................................................................................................................................. 18 B.2 Wood species ................................................................................................................................................. 18 B.3 Sapwood/heartwood .................................................................................................................................. 19 B.4 Treatability ..................................................................................................................................................... 19 B.5 Additional notes in Tables B.1, B.2, and B.3 ....................................................................................... 20 B.6 Convention on International Trade in Endangered Species (CITES) ......................................... 20 B.7 Adding new wood species or adjust data in Table B.1 .................................................................... 20 Annex C (informative)

Classification of treatability with aqueous wood preservatives ................. 58 Annex D (informative)

Classification of permeability to water ............................................................... 60 D.1 General ............................................................................................................................................................. 60 D.2 Principles for classification of permeability to water .................................................................... 60 SIST EN 350:2017

EN 350:2016 (E) 3 Annex E (informative)

Testing durability to disfiguring fungi .................................................................. 61 E.1 General ............................................................................................................................................................. 61 E.2 Testing durability to disfiguring fungi .................................................................................................. 61 E.3 Classification of durability to disfiguring fungi ................................................................................. 61 Annex F (informative)

Classification of performance .................................................................................. 62 F.1 General ............................................................................................................................................................. 62 F.2 Principles of the assessment of performance .................................................................................... 62 F.3 Principles of the classification of performance ................................................................................. 63 Annex G (informative)

Form to be used for the inclusion of new data on wood species / wood-based material ................................................................................................................................... 64 Bibliography ................................................................................................................................................................. 67

SIST EN 350:2017

EN 350:2016 (E) 4 European foreword This document (EN 350:2016) has been prepared by Technical Committee CEN/TC 38 “Durability of wood and wood-based products”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by February 2017, and conflicting national standards shall be withdrawn at the latest by February 2017. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 350-1:1994 and EN 350-2:1994. Wood durability is an important factor that influences the service life of a wood product. This standard provides input to service life prediction of wood and wood-based products. It’s intended to give guidance on using wood products appropriate for different end-uses avoiding excessive requirements. It also ranks durability against wood-decay organisms of various wood species thereby allowing species of appropriate durability to be selected for a particular use. It will however be emphasized that the biological durability rating of wood species given in Annex B cannot be regarded as any guarantee of performance in service. There are many other factors influencing service life of a wood product, such as the principles of good design, use conditions, climate, maintenance which should be taken into consideration. According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 350:2017

EN 350:2016 (E) 5 1 Scope This European Standard gives guidance on methods for determining and classifying the durability of wood and wood-based materials against biological wood-destroying agents. The methods can be applied either to individual wood species, batches of wood and processed wood-based materials, including heat-treated, preservative-treated wood and modified wood. However, this standard is not intended to replace testing of the efficacy of biocides. The wood-destroying agents considered in this standard are: — wood-decay fungi (basidiomycete and soft-rot fungi); — beetles capable of attacking dry wood; — termites; — marine organisms capable of attacking wood in service. Data on the biological durability of selected wood species considered of economic importance in European countries are presented in Annex B (informative), which also provides information relating to their geographical origin, density, sapwood width and treatability. NOTE Treatability, durability to disfiguring fungi, permeability to water and performance in use of wood and wood-based materials are also important issues. However, because standardized methods aiming to assess and classify these factors do not exist and/or have not been extensively experienced yet, preliminary guidance is given in Annex C (informative) for the classification of wood treatability with aqueous wood preservatives, Annex D (informative) for the classification of the permeability to water, Annex E (informative) for the durability to disfiguring fungi, and Annex F (informative) for the classification of performance. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 20-1, Wood preservatives - Determination of the protective effectiveness against Lyctus Brunneus (Stephens) - Part 1: Application by surface treatment (laboratory method) EN 461, Wood preservatives - Determination of the preventive action against recently hatched larvae of Hylotrupes bajulus (Linnaeus) - Part 1: Application by surface treatment (laboratory method) EN 49-1, Wood preservatives - Determination of the protective effectiveness against Anobium punctatum (De Geer) by egg-laying and larval survival - Part 1: Application by surface treatment (Laboratory method) EN 117, Wood preservatives - Determination of toxic values against Reticulitermes species (European termites) (Laboratory method) EN 252, Field test method for determining the relative protective effectiveness of a wood preservative in ground contact EN 275, Wood preservatives - Determination of the protective effectiveness against marine borers ENV 12038, Durability of wood and wood-based products - Wood-based panels - Method of test for determining the resistance against wood-destroying basidiomycetes SIST EN 350:2017

EN 350:2016 (E) 6 EN 13556, Round and sawn timber - Nomenclature of timbers used in Europe CEN/TS 15083-1, Durability of wood and wood-based products - Determination of the natural durability of solid wood against wood-destroying fungi, test methods - Part 1: Basidiomycetes CEN/TS 15083-2, Durability of wood and wood-based products - Determination of the natural durability of solid wood against wood-destroying fungi, test methods - Part 2: Soft rotting micro-fungi EN 16449, Wood and wood-based products - Calculation of the biogenic carbon content of wood and conversion to carbon dioxide ISO 13061-2, Physical and mechanical properties of wood — Test methods for small clear wood specimens — Part 2: Determination of density for physical and mechanical tests 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 wood species trade name according to EN 13556 which can on occasion include more than one botanical tree species Note 1 to entry: E.g. European oak which comprises both Quercus robur and Q. petraea. 3.2 pilot name for a wood species result of a consensual choice due to practical considerations retaining the usual name under which the wood is the most widely commercialised, adopted either by the main exporting country or by the main importing country Note 1 to entry: Pilot names are established since 1954 in the nomenclature of the ATIBT. 3.3 set clearly identifiable collection of units of wood or wood-based products, originating from a commercial supply of a defined origin (single or not) and likely comprising only some of the variability of the wood species or of the wood-based material Note 1 to entry: E.g. wood species sourced from a restricted geographical area. 3.4 wood-based material any processed matrix containing and/or made of a specific percentage of wood Note 1 to entry: Wood-based materials are those derived from trees and include amongst others heat-treated wood and any other material modified by chemical, physico-chemical or physical process, glue-laminated wood, wood-based panels, wood polymer composites and treated with wood preservatives. This standard is not meant to test all ligno-cellulosic materials (e.g. bamboo, reed, straw, flax) as such and would require methodological adaptions to do so. SIST EN 350:2017

EN 350:2016 (E) 7 3.5 modified wood wood that undergoes the action of a chemical, biological or physical agent, resulting in a permanent desired property enhancement Note1 to entry: If the modification is intended for improved resistance to biological attack, then the mode of action is assumed to be non-biocidal. 3.6 durability to biological agents inherent resistance of a wood species or a wood-based material against wood decay organisms Note 1 to entry: This inherent resistance is due to the presence of natural components that can exhibit different levels of toxicity towards biological organisms and/or to anatomical particularities or a specific constitution of certain wood-based materials. 3.7 sapwood outer zone of wood that, in the growing tree, contains living cells and conducts sap Note 1 to entry: Depending on the species, age of the tree and the growing conditions the proportions of sapwood and heartwood can vary. Note 2 to entry: Frequently paler than heartwood though not always distinguishable from heartwood in some wood species. Note 3 to entry: Sapwood of all wood species is considered to be non-resistant against decay fungi unless other data are available. Sapwood can have different levels of resistance against wood boring insects (excluding termites). 3.8 heartwood inner zone of wood that, in the growing tree, has ceased to contain living cells or to conduct sap Note 1 to entry: Frequently darker than sapwood though not always distinguishable from sapwood in some wood species. 3.9 transition wood wood in a zone between the sapwood and the heartwood Note 1 to entry: The transition wood can be regarded as a region of the heartwood that has not fully matured. This is only distinguishable in very few wood species. In general, its biological durability, treatability and permeability to water is intermediate between that of sapwood and heartwood. 3.10 juvenile wood set of few growth rings of woody tissue nearest the centre of the tree, often having abnormal properties Note 1 to entry: Juvenile wood is a zone near to the pith, displaying marked ring to ring changes in its properties. There is no clear consensus as to where this zone ends. It is generally thought to end at 10 to 20 rings from the pith, but it depends on the wood species. Note 2 to entry: The durability, permeability to water and treatability of juvenile wood can be different from that of mature heartwood. SIST EN 350:2017

EN 350:2016 (E) 8 3.11 permeability to water ease with which water penetrates a wood-based matrix (wood of a particular species, wood-based material) and is released by evaporation 3.12 performance ability of a wood species or a wood-based material to withstand deterioration over time 4 Sampling of wood and wood-based materials to be tested 4.1 Testing wood species 4.1.1 General The origin of test specimens and the number of replicates is of great importance for the reliability of the test results. The reliability of conclusions relating to the durability of a wood species increases with the number and diversity of growing sites from which trees are taken and the number of replicates from those trees. The recommendations given in 4.1.2 to 4.1.3 shall be regarded as minima. NOTE Background information on sampling can be found in ISO 2859-2 and ISO 3129. 4.1.2 Sampling logs A log shall be taken from at least 3 trees of the species under test, originating from 3 different sites representative of the diversity of the geographical regions or sites where the tree species grows. Samples should be taken from at least 5 planks, originating from at least 3 trees when only sawn wood is available (see Annex A). If high between-tree variation is expected (e.g. different botanic species), it’s recommended to test a larger number of trees (e.g. 5 – 10). NOTE 1 It can be useful to test in parallel material derived from wood species with known durability. Each log shall be of sufficient size to permit the required number of test specimens to be obtained from it. Each log shall be taken from the main trunk avoiding its extreme ends. Knots and other features which can influence durability shall be avoided. Sampling shall consider sapwood, heartwood and juvenile wood separately. While testing heartwood, the region within at least 3 cm of the pith shall be excluded in order to avoid juvenile wood, which is often less resistant than the mature heartwood. For heartwood sampling, both the inner (closest to the pith) and the outer (closest to the sapwood and thus including transition wood) parts of the heartwood shall be incorporated. NOTE 2 For some species, in order to better assess the variability, there can be a need to sample the transition wood and juvenile wood separately. For logs of large diameter, a larger number of samples shall be taken from the outer part (outer third of the heartwood radius which is closest to the sapwood). For each part of the wood (heartwood, transition wood, sapwood, juvenile wood) to be tested, at least 30 test specimens shall be taken for each test variable (for example “test method” or “test organism”). A minimum of 6 specimens shall be taken from each log. SIST EN 350:2017

EN 350:2016 (E) 9 Depending on the selected test method, additional specimens might be required to determine the density of the wood species and the moisture content of the specimens. The sampling shall be done according to the relevant standards (ISO 13061-2 for density and ISO 13061-1 for moisture content). NOTE 3 A scheme of a suitable preparation and distribution of the specimens for testing is showed in Annex A. 4.1.3 Sampling sawn timber Wood placed on the market is mostly available as sawn timber and hence it is difficult to identify pieces originating from specific trees. For this reason, it is preferred to sample as many pieces as possible so as to better estimate the overall durability. A minimum of 30 pieces originating from minimum 5 batches and providing 1 specimen per piece is required. The general considerations described in 4.1.2 related to sampling also apply for sawn wood. 4.2 Testing of sets of wood Since timbers are mostly presented on the market as commercial supplies there is a need to assess their durability. A maximum of wood pieces shall be used for the realization of the test specimens (e.g. 2 replicate test specimens from each of 20 pieces are preferred to 10 specimens from each of 4 pieces). To give a good indication on the variability of the tested set of wood, it is recommended to test at least 30 specimens per variable (for example “test method” or “test organism”). 4.3 Testing of wood-based materials The sampling should take into account the variability of the wood-based material to be tested. For each variation in processing parameter (e.g. a change in temperature, particle size, wood species), a minimum of 30 specimens is required, derived from at least 3 produced items (e.g. boards) sampled at random from 3 different batches. A minimum of 5 specimens from each batch should be tested. If the material contains both sapwood and heartwood, care has to be taken that both sapwood and heartwood are used to produce the test specimens. 5 General principles for testing and classification 5.1 General principles for testing wood specimens When testing a wood species, an identification of the tree or the wood species shall be done. Wood species shall be specified according to EN 13556. In order to get a homogeneous set of samples in terms of moisture content, the test specimens shall be conditioned prior to testing in a ventilated conditioning chamber at controlled temperature and relative humidity, until their weight and moisture content are stabilized. The sample selection requirement for reference specimens shall follow the instructions of the relevant test method. If several wood species are tested at the same time, one set of reference specimens is sufficient. Test timber used to determine the durability of a wood species should not be oven-dried at temperatures above 60 °C prior to the test. If laboratory test vessels are used, reference specimens and test specimens shall be tested in separate vessels. EN 73 or EN 84 are ageing procedures which might be required prior to biological testing. The properties of the test specimen shall, as far as possible, be representative for the wood species being tested even if this does not follow the instruction given on sample selection in the relevant test SIST EN 350:2017

EN 350:2016 (E) 10 standard. However, the results still cannot be expected to take into account the full range of variation of properties within a species. EXAMPLE 1: If the test method excludes the use of “wood of resinous appearance”, but the species to be tested normally has a naturally resinous appearance, this exclusion is ignored. EXAMPLE 2: If the test method requires a certain number of growth rings per centimetre, this restriction is ignored if growth rings do not exist or are too widely spaced. This is of importance for some tropical timbers, because it is sometimes impossible to see the growth rings; the rings can also correspond not to the annual growth but to the alternation of dry and wet seasons. 5.2 General principles for the classification of durability The durability of a wood species or a wood-based material to various wood destroying organisms is tested using methods described in relevant European Standards. The use of replicate specimens is a requirement in all test methods. For wood species, durability classes refer only to heartwood. Sapwood is always regarded as not durable, unless test data provide different information. Based on test results, the durability of a wood species or a wood-based material to the various wood-destroying organisms is classified within: — a five grade scale for decay basidiomycete fungi and soft rotting micro-fungi Table 1 — Durability classes (DC) of wood and wood-based materials to attack by decay fungi Durability class Description DC 1 Very durable DC 2 Durable DC 3 Moderately durable DC 4 Slightly durable DC 5 Not durable NOTE 1 This five-grade scale was initially designed in order to inform on the expected levels of performance of wood when used in contact with ground (service conditions as described for use class 4 in EN 335). Most of the data on biological durability against fungi, reported in Annex B, are derived from field tests, mainly performed according to the EN 252 standard. In other use classes, the service conditions can result in wood performance which differs from that implied by this classification. — a two grade scale for beetles (Hylotrupes bajulus, Anobium punctatum, Lyctus brunneus and Trichoferus holosericeus Rossi (= Trichoferus holosericeus cinereus) Table 2 — Durability classes (DC) of wood and wood-based materials to attack by wood-boring beetles Durability class Description DC D Durable DC S Not durable Durability to Hylotrupes bajulus is only given for softwoods (see Annex B, Table B.1) as hardwoods are not attacked. SIST EN 350:2017

EN 350:2016 (E) 11 Durability to Lyctus brunneus is not mentioned in the list (see Annex B, Tables B.2 and B.3) as only the wood of starch-containing hardwood species with pores of suitable width is susceptible. For species with highly susceptible sapwood a specific note appears in the ‘Remarks’ column. Softwoods are not attacked. Durability to Trichoferus holosericeus, which only attacks hardwoods in Southern Europe, is mentioned in the ‘Remarks’ column if a wood species is known as highly susceptible. NOTE 2 The classification of a wood species or wood-based material as ‘not durable’ does not necessarily indicate that different products made with this material will be equally destroyed during their life in service. Susceptibility to insect attack may change over time through chemical changes in extractives, such as the fate of starch, which is the main source of food. Additionally, susceptibility of any commodity to biological attack may be influenced by other factors, such as its moisture content, design, maintenance and presence of surface coatings. — a three-grades scale for termites Table 3 — Durability classes (DC) of wood and wood-based materials to attack by termites Durability class DC Description DC D Durable DC M Moderately durable DC S Not durable — a three-grades scale for marine organisms (or marine borers) Table 4 — Durability classes (DC) of wood to attack by marine organisms Durability class Description DC D Durable DC M Moderately durable DC S Not durable 6 Test methods and classi

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