SIST EN 350:2017

SLOVENSKI STANDARD
01-februar-2017
Nadomešča:
SIST EN 350-1:1995
SIST EN 350-2:1995
Odpornost lesa in lesnih izdelkov - Preskušanje in razvrstitev odpornosti lesa in
lesnih izdelkov proti biološkim agensom
Durability of wood and wood-based products - Testing and classification of the durability
to biological agents of wood and wood-based materials
Dauerhaftigkeit von Holz und Holzprodukten - Prüfung und Klassifikation der
Dauerhaftigkeit von Holz und Holzprodukten gegen biologischen Angriff
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
Ta slovenski standard je istoveten z: EN 350:2016
ICS:
79.040 Les, hlodovina in žagan les Wood, sawlogs and sawn
timber
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 350
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2016
EUROPÄISCHE NORM
ICS 79.040 Supersedes EN 350-1:1994, EN 350-2:1994
English Version
Durability of wood and wood-based products - Testing and
classification of the durability to biological agents of wood
and wood-based materials
Durabilité du bois et des matériaux dérivés du bois - Dauerhaftigkeit von Holz und Holzprodukten - Prüfung
Méthodes d'essai et de classification de la durabilité und Klassifikation der Dauerhaftigkeit von Holz und
vis-à-vis des agents biologiques du bois et des Holzprodukten gegen biologischen Angriff
matériaux dérivés du bois
This European Standard was approved by CEN on 18 June 2016.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of 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
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 350:2016 E
worldwide for CEN national Members.

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
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

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.
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 46−1, 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
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.
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.
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.
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
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.
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
Description
DC
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 classification system
NOTE Annex G provides a template form presenting the information which is required for adding new data to
the standard.
6.1 Durability to wood-destroying fungi
6.1.1 General
Durability to a well-defined set of wood-destroying fungi can be assessed by performing laboratory
tests (6.1.2.l and 6.1.2.2).
NOTE Field tests allow determining the durability of a wood species or a wood-based material in different
end-uses (above-ground, in-ground) and expose it to a wider range of wood colonising and destroying organisms
and long term conditioning through exposure to weather. Laboratory tests are more specific as they are
performed under fully controlled conditions.
6.1.2 Testing durability against basidiomycete and soft-rot fungi
6.1.2.1 For solid wood and solid wood-based material
Durability against wood decay fungi based on a laboratory test shall be determined using
CEN/TS 15083-1 for basidiomycetes and CEN/TS 15083-2 for soft rotting micro fungi.
The criteria for determining durability classes (DC), based on the CEN/TS 15083-1 are presented in
Table 5.
Table 5 — Durability classes (DC) of wood to fungal attack (basidiomycete fungi)
Durability class Description Percentage mass loss (ML)
DC 1 Very durable ML ≤ 5
DC 2 Durable 5 < ML ≤ 10
DC 3 Moderately durable 10 < ML ≤ 15
DC 4 Slightly durable 15 < ML ≤ 30
DC 5 Not durable 30 < ML
ML = highest of the median mass losses (in %) determined for test specimens exposed to each of
the used test fungi
The criteria for determining durability classes (DC), based on the CEN/TS 15083-2 are presented in
Table 6. In this test, preliminary DC is based on the median of the mass loss for hardwoods or the MOE
(apparent modulus of elasticity measured in 3 point bending according to EN 317) for softwoods.
Table 6 — Durability classes (DC) of wood to fungal attack (soft rot)
Durability class Description x value
DC 1 Very durable x ≤ 0,10
DC 2 Durable 0,10 < x ≤ 0,20
DC 3 Moderately durable 0,20 < x ≤ 0,45
DC 4 Slightly durable 0,45 < x ≤ 0,80
DC 5 Not durable x > 0,80
Hardwoods: x = median value of mass loss for timber test specimens / median value of mass
loss for reference timber test specimens
Softwoods: Calculate the “x value” for the test timber but using loss of MOE.
Wood species known to be not durable should be used to test the virulence of fungi. Commonly, Pinus
sylvestris sapwood is used for testing softwoods and Fagus sylvatica for testing hardwoods.
The validity criteria of the test are given in the corresponding test method.
The durability classification is based on the highest median mass loss determined for all the test
specimens exposed to each of the test fungi.
Additional information about the spread of individual mass loss values should be provided. If individual
mass loss values are distributed over two durability classes (x and y) with at least 40 % of values being
in each of them, the retained durability class should not be based on the median mass loss but
expressed as falling between “x – y “. High levels of variability should be clearly mentioned in the test
report, e.g. by “v” as in the example presented in Table 7.
The spread of individual values can be expressed in test reports based on fitted probability density
functions, as presented in Table 7.
Table 7 — Example of distribution of classes of mass loss values of the tested material in
different durability classes based on fitted probability density functions
Median
Wood Durability
mass
% DC1 % DC2 % DC3 % DC4 % DC5
species class
loss (%)
A 2,2 83,0 15,6 1,3 0,1 0,0 1
B 7,3 27,2 46,4 21,8 4,6 0,0 2v
C 8,9 23,5 33,2 23,7 19,0 0,6 2v
D 28,2 0,0 0,0 13,4 46,6 40,0 4–5
“v” indicates that the species exhibits an unusually high level of variability
6.1.2.2 For wood-based material other than solid wood
The test procedure described in ENV 12038 applies to wood-based products panels and the
classification shall be undertaken according to Tables 5 and 6.
NOTE 1 CEN/TS 1099 specifies this method for testing biological durability of plywood.
NOTE 2 EN 15534–1 specifies this method for testing biological durability of wood polymer composites.
6.1.2.3 Durability of wood and wood-based materials used in-ground
The EN 252 standard provides a method which is suitable for assessing the durability of wood and
wood-based materials in direct contact with the ground (use class 4). At least 30 stakes of the test wood
species or wood-based material shall be used in place of the impregnated test stakes described in this
standard. Stakes of Pinus sylvestris sapwood and Fagus sylvatica shall be used as references to measure
microbiological activity of the field soil throughout the test. They shall be replaced as necessary when
they fail.
It is recommended to perform the test in more than one field site.
NOTE The field conditions can vary between different test sites and comparing the results can consequently
be difficult.
In the absence of a specific standard providing a test method allowing the determination of durability
classes, the average life of wooden stakes used in-ground can be expressed relative to the life of the
reference stakes as given in Table 8.
Table 8 — Durability classes (DC) to fungal attack for wood used in-ground determined using
field tests based on EN 252
Durability class (DC) Description Results of field tests
expressed as x values
DC 1 Very durable x > 5,0
DC 2 Durable 3,0 < x ≤ 5,0
DC 3 Moderately durable 2,0 < x ≤ 3,0
DC 4 Slightly durable 1,2 < x ≤ 2,0
DC 5 Not durable x ≤ 1,2
x value = average life of stakes / average life of the more durable set of reference stakes
6.1.2.4 Durability of wood and wood-based materials used above-ground
Different field test methods, standardized or not, have been developed in order to assess the durability
of wood and wood-based materials in above-ground situations (use classes 3) and can be used for that
purpose, such as the L-joint (EN 330), lap-joint (CEN/TS 12037), ground proximity and double-layer
tests.
It is recommended to perform the test in more than one field site.
NOTE The climate can vary between different test sites and comparing the results can consequently be
difficult.
6.2 Durability to larvae of dry wood-destroying beetles
The durability of wood and wood-based-materials to attack by Hylotrupes bajulus, Anobium punctatum
and Lyctus brunneus shall be tested using procedures based on those in EN 46-1, EN 49-1 and EN 20-1
respectively.
If durability to Trichoferus holosericeus is required, tests shall be carried out as for Hylotrupes bajulus,
but using Fagus sylvatica as the reference species.
Specimens of the test wood species (see clause 4) shall be used in place of the preservative treated
wood specimens mentioned in those standards.
A wood species or a wood-based material is classified as “not durable” if one or more live insects of the
respective test organism are found at the end of the test. If no live insects are found at the end of the
respective test, and if the validity criteria for the respective test in the reference species are fulfilled, the
test species is classified as “durable”.
NOTE If it is expected, that the durability of a specific wood or wood-based material is based on behavioural
aspects of wood destroying adult beetles prior to egg laying, different test methods can need to be applied.
6.3 Durability to termites
The durability of wood and wood-based materials to attack by subterranean termites shall be tested
using procedures based on EN 117 in the absence of any other more specific standard. The durability
should be tested against the termite genus of major economic importance occurring in the area where
the wood is meant to be used.
NOTE 1 Usually, durability is tested on Reticulitermes termites in Europe and most frequently on Coptotermes,
Nasutitremes and Heterotermes in member state tropical regions outside the European continent, depending on
their geographical areas.
Specimens of the test wood species or wood-based material (see section 4) shall be used in place of the
preservative treated wood specimens mentioned in EN 117.
The test procedures described in EN 117 results in attack ratings on a scale 0 - 4. The test shall be
considered valid if the reference not durable species has a rating of 4 in the test.
The durability of the species or wood-based material under test shall be classified in accordance with
Table 9.
Table 9 — Classes of durability of wood species and wood-based materials to termite attack
based on EN 117 ratings
Durability class Description Rating
a
DC D Durable ≥ 90 % “0 or 1” and max 10 % “2”
DC M Moderately durable < 50 % “3, 4”
DC S Not durable ≥ 50 % “3, 4”
a
90 % of the test samples rated 0 or 1 and a maximum of 10 % of the test samples rated 2 and 0 % “3 and 4”
NOTE 2 Durability class “DC M”, derived from a laboratory test, is of informative value only. Other parameters
like population size and dynamics of occurring termites in the intended geographical region, where the wood or
wood-based material will be used, need also to be evaluated.
NOTE 3 So far, no standardized European methodology allowing assessing specifically the durability against
drywood termites (Kalotermes flavicollis and Cryptotermes spp.) exists.
6.4 Durability to marine organisms
The durability of wood and wood-based materials to attack by marine organisms shall be tested using
procedures based on those described in EN 275.
NOTE Durability to marine borers is best tested in geographical locations where the wood or wood-based
material is intended for use to ensure their exposure to as wide a range of marine borers as can be encountered
when in service.
Specimens of the test wood species shall be used in place of the preservative treated wood specimens in
EN 275.
The reference specimens shall be Pinus sylvestris sapwood. Any other not durable species could be
added for virulence control. They shall be replaced as necessary when they fail.
The test shall be used to determine the time needed for the test specimens to fail.
The durability of the species under test shall be classified in accordance with Table 10.
Table 10 — Classes of durability of wood or wood-based materials to attack by marine
organisms using tests based on EN 275
Durability class Description Results of field tests
expressed as x
DC D Durable x > 5,0
DC M Moderately durable 3 < x ≤ 5
DC S Not durable x ≤ 3
x = average life of test specimens/average life of the more durable set of reference specimens
Annex A
(informative)
Example of scheme for sampling heartwood
A.1 Logs
A scheme for the cutting of laths from logs to represent the outer and inner heartwood is illustrated in
Figure A.1. This also shows the cutting of the laths into test specimens. The length of the logs necessary
for sampling depends on the amount of specimens required for the relevant test procedure.

Key
1 log
a laths from the outer part of the heartwood
b laths from the inner part of the heartwood
c test specimen
Figure A.1 — Sampling from logs (1) - Taking laths from the outer (a) and inner (b) part of the
heartwood and cutting them into test specimens (c)
A.2 Central boards
A scheme for the cutting of laths from centrally cut boards to represent the outer and inner heartwood
is illustrated in Figure A.2. This also shows the cutting of the laths into test specimens. The length of the
boards necessary for sampling depends on the amount of specimens required for the relevant test
procedure.
Key
a sap
b outer part
c inner part
d pith
e test specimens
Figure A.2 — Sampling from central boards. Taking laths from the outer and inner part of the
heartwood and cutting them into test specimens
Annex B
(informative)
Guide to biological durability and treatability of wood species marketed in
Europe
B.1 General
Wood is a biological material. Its natural resistance to various forms of biological attack is affected by
many factors. Consequently, definitive statements about biological durability cannot be made without
having accurate and comprehensive test data. However, based on the information currently available,
EN 350 gives guidance on the durability of the heartwood of selected wood species to degradation by a
range of organisms.
The data given in the tables are based upon information drawn from various sources, including
historical records, practical experience, laboratory tests, field tests and other data. Old data come from
the previous version EN 350-2:1994. The omission of a species does not necessarily imply that it is
unsuitable for use. A species can have been omitted because it was not considered of sufficient
economic importance to be included, or because no or insufficient data were available to classify it.
For fungi, two durability classifications are listed, noted as follows: X (Y). The first one is usually derived
from the rating of heartwood stakes exposed h
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