SIST EN 460:2023
(Main)Durability of wood and wood-based products - Guidance on performance
Durability of wood and wood-based products - Guidance on performance
This document gives guidance on the selection of wood of wood and wood based products for use in situations where they may be subject to degradation by fungi or wood destroying insects. This guidance includes information on factors that can influence the service life of a wood or wood-based product when considering biological degradation. This document is a step toward the evaluation of the service life of a wood product.
This document does not consider:
1) the durability characteristics of the glue used in wood-based products;
2) the aesthetic function of wood products (discoloration, surface weathering, mould).
Dauerhaftigkeit von Holz und Holzprodukten - Leitfaden zur Bestimmung der Leistungsfähigkeit
Dieses Dokument gibt eine Anleitung zur Auswahl von Holz und Holzprodukten zur Verwendung unter Bedingungen, in denen sie der Zerstörung durch Pilze oder Holz zerstörende Insekten ausgesetzt sein können. Diese Leitlinien enthalten Informationen über Faktoren, die die Gebrauchsdauer eines Holzes oder Holzproduktes unter Berücksichtigung des biologischen Abbaus beeinflussen können. Dieses Dokument ist ein Ansatz zur Bewertung der Gebrauchsdauer eines Holzprodukts.
Dieses Dokument berücksichtigt nicht:
1) die Dauerhaftigkeit des Klebstoffs, der in Holzprodukten verwendet wurde;
2) die ästhetische Funktion von Holzprodukten (Verfärbung, Oberflächenverwitterung, Schimmel).
Durabilité du bois et des matériaux à base de bois - Guide pour déterminer la performance
Le présent document fournit des recommandations relatives à la sélection de bois et de matériaux dérivés du bois pour une utilisation dans des situations où ils peuvent être soumis à une dégradation par des champignons ou des insectes xylophages. Ces recommandations incluent des informations sur les facteurs susceptibles d'influer sur la durée de service d'un bois ou d'un matériau à base de bois, compte tenu de la dégradation biologique. Le présent document constitue un progrès vers l'évaluation de la durée de service des éléments en bois.
Le présent document ne traite pas :
1) des caractéristiques de durabilité de la colle utilisée avec les matériaux à base de bois ;
2) de la fonction esthétique des éléments en bois (décoloration, vieillissement d’aspect de la surface, moisissure).
Trajnost lesa in lesnih proizvodov - Navodilo za učinkovitost
Ta dokument vsebuje navodilo za izbor lesa in lesnih proizvodov za uporabo v pogojih, kjer lahko obstaja možnost razgradnje zaradi gliv ali organizmov, ki uničujejo les. Navodilo vključuje informacije o dejavnikih, ki lahko vplivajo na življenjsko dobo lesa ali lesnih proizvodov ob upoštevanju biološke razgradnje. Ta dokument je korak v smeri ocenjevanja življenjske dobe lesnega izdelka.
Dokument ne upošteva:
1) lastnosti trajnosti lepila, ki se uporablja v lesnih izdelkih;
2) estetske funkcije lesnih proizvodov (razbarvanje, pospešeno staranje površine, plesen.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 460:2023
01-junij-2023
Nadomešča:
SIST EN 460:1995
Trajnost lesa in lesnih proizvodov - Navodilo za učinkovitost
Durability of wood and wood-based products - Guidance on performance
Dauerhaftigkeit von Holz und Holzprodukten - Leitfaden zur Bestimmung der
Leistungsfähigkeit
Durabilité du bois et des matériaux à base de bois - Guide pour déterminer la
performance
Ta slovenski standard je istoveten z: EN 460:2023
ICS:
79.040 Les, hlodovina in žagan les Wood, sawlogs and sawn
timber
SIST EN 460:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 460:2023
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SIST EN 460:2023
EN 460
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2023
EUROPÄISCHE NORM
ICS 79.040 Supersedes EN 460:1994
English Version
Durability of wood and wood-based products - Guidance
on performance
Durabilité du bois et des matériaux à base de bois - Dauerhaftigkeit von Holz und Holzprodukten -
Guide pour déterminer la performance Leitfaden zur Bestimmung der Leistungsfähigkeit
This European Standard was approved by CEN on 2 January 2023.
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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 460:2023 E
worldwide for CEN national Members.
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EN 460:2023 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Performance . 7
4.1 General . 7
4.2 Exposure . 8
4.2.1 General . 8
4.2.2 Climate . 8
4.2.3 Use class . 9
4.2.4 Design . 9
4.2.5 Quality of installation . 9
4.2.6 Maintenance . 9
4.2.7 Usage . 10
4.3 Consequence of failure . 10
4.4 Service life . 10
4.4.1 General . 10
4.4.2 Limit state . 11
4.5 Materials . 11
4.5.1 General . 11
4.5.2 Natural durability . 11
4.5.3 Conferred durability . 11
4.5.4 Guidelines . 12
5 Requirements on biological durability in different end use conditions . 12
5.1 General . 12
5.2 Durability against wood-destroying fungi . 13
5.3 Durability against beetles . 13
5.4 Durability against termites . 13
5.5 Durability against marine borers . 13
5.6 Durability against combined biological hazards . 13
Annex A (informative) Consequence of Failure (COF) . 14
Annex B (informative) Guidance on the durability classes of wood species in use class . 15
Annex C (informative) Important factors in the relationship between expected service life
and biological durability . 17
Bibliography . 19
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EN 460:2023 (E)
European foreword
This document (EN 460:2023) has been prepared by Technical Committee CEN/TC 38 “Durability of
wood and wood-based products”, the secretariat of which is held by SIS.
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 August 2023, and conflicting national standards shall be
withdrawn at the latest by August 2023.
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 460:1994.
EN 460:2023 includes the following significant technical changes with respect to EN 460:1994:
— title change;
— the introduction of a decision process for performance specification of wood and wood-based
products based on (i) materials and exposure, (ii) presentation of design life and (iii) articulation of
consequence of failure.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
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, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
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EN 460:2023 (E)
Introduction
There is increasing need to understand the service life of wood products, especially in construction.
Service life in the Construction Products Regulation (Regulation (EU) No 305/2011 (CPR) and its
equivalent in non-EU countries) can be understood as performance within an economically acceptable
period, under typical exposure and maintenance scenarios.
This document is concerned with the service life of wood materials and wood products, especially in
construction. The purpose of this document is to provide guidance to help the user to select a wood or
wood-based material based of appropriate biological durability based on information about the end use
environment and the target service life.
For the service life of structures, refer to EN 1990 and EN 1995-1-1.
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EN 460:2023 (E)
1 Scope
This document gives guidance on the selection of wood and wood-based products for use in situations
where they can be subject to degradation by fungi, wood destroying insects or marine borers. This
guidance includes information on factors that can influence the service life of a wood or wood-based
product when considering biological degradation. In many end uses, design, workmanship and
maintenance will also influence the service life of the wood or wood-based product.
This document is a step toward the evaluation of the service life of a wood product.
This document does not consider:
1) the durability characteristics of the glue used in wood-based products;
2) the aesthetic function of wood products (discoloration, surface weathering, mould).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1001-2, Durability of wood and wood based products — Terminology — Part 2: Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1001-2 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
• ISO Online browsing platform: available at https://www.iso.org/obp
• IEC Electropedia: available at https://www.electropedia.org/
3.1
biological durability
inherent resistance of a wood species or a wood-based material against wood-destroying organisms
Note 1 to entry: This can be a natural or a conferred durability.
3.2
coating
product, normally applied in a liquid form to a surface, that forms a film possessing protective properties
3.3
component
product manufactured as a distinct unit to serve a specific function or functions
3.4
conferred durability
improved resistance of a wood species to biological degradants provided by a treatment process
(chemical, physical, etc.) such as wood preservation or wood modification
3.5
consequence of failure (COF)
significance of product failure in service determined by the outcome of a failure expressed in terms of
personnel safety, economic loss, and/or damage to the environment
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3.6
critical biological hazard
biological hazard (or hazards) most significant in the end use application and its geographical location
3.7
design life
service life intended by the designer
3.8
likelihood of failure
probability that a wood component will reach its limit state within the design life
3.9
limit state
state beyond which the structure (or product) no longer satisfies the relevant design criteria
[SOURCE : EN 1990:2002, Clause 3.1.2.14 (CEN/TC250/SC10 N 523)]
Note 1 to entry: The limit state is commonly reached before loss of function is complete.
3.10
material resistance
inherent ability of a material to endure a specific biological hazard through a combination of natural
and/or conferred durability and moisture dynamic behaviour relevant for the different biological agents
3.11
moisture dynamics
physical characteristic of a wood material or wood product to respond to changing environmental
conditions and take up and release moisture (vapour or liquid)
Note 1 to entry: The moisture dynamics of a wood species or a wood-based material can be tested using the
method described in CEN/TS 16818.
3.12
natural durability
inherent resistance of a wood species to attack by wood-destroying organisms
3.13
overlay
one or more sheets or films, for example impregnated paper, plastics, resin film, metal that protect a wood
surface
3.14
performance
ability of a wood species or a wood-based material to withstand deterioration over time and fulfil
essential functions
3.15
permeability to water
ease with which water penetrates a wood-based matrix (wood of a particular species, wood-based
material)
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3.16
service life
period of time after installation during which a building, structure or component parts meet or exceed
the performance requirements
Note 1 to entry: This standard does not consider the service life of entire structures, it is limited to the properties
of the material and service life of components.
3.17
serviceability
ability of a structure or structural member to satisfy, with planned maintenance, its design performance
requirements over the design service life
[SOURCE : EN 1990:2002, Clause 3.1.2.3 (CEN/TC 250/SC 10 N 523)]
3.18
wood modification
non-biocidal process of a chemical, biological, or physical alteration of the cell wall substance of wood,
resulting in a permanent desired property enhancement to primarily enhance biological durability and
dimensional stability
Note 1 to entry: This includes thermal modification and chemical modification.
3.19
wood preservative treatment
application of wood preservative products in liquid form for the preventive treatment of wood resulting
in a desired improvement of their properties in order to protect them from degradation by wood
destroying fungi, wood-destroying insects (termites and beetles) or marine borers
Note 1 to entry: The usual processes are superficial (soaking or spraying) or penetrating treatment (double
vacuum autoclave or vacuum autoclave and pressure).
4 Performance
4.1 General
When wood-destroying organisms are likely to degrade wood in service, a suitable approach for meeting
service life needs to be selected. There are two principal approaches:
1) by design - changing the habitat conditions e.g. with wood destroying fungi minimizing the moisture
risk to which the wooden component is exposed or e.g. with insects by denying the access through
construction measures;
2) by durability - either select the heartwood of a wood species of sufficient natural durability or ensure
sufficient conferred durability by treatment with a wood preservative, wood modification or non-
biocidal treatment to manage the challenge presented in the use environment.
Typically, it is a combination of both.
This standard provides information to aid the user in the choice of a wood or wood-based material for a
product, knowing its use class with the corresponding end use environment and the envisioned target
service life. No attempt has been made to quantify the service life that could be expected from a particular
combination. This is considered in national interpretation documents e.g. standards, guidelines, technical
reports and service life prediction tools.
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A schematic diagram to illustrate a decision-making process for determining the performance of a wood
product is shown in Figure 1. The features defining the exposure of a material or product are
multifaceted. Considered together, the exposure and the service life requirement for the product is the
framework for identifying suitable wood and wood-based materials to meet these requirements.
Figure 1 — Schematic illustration of a decision process for performance specification linked to
clauses in this document
4.2 Exposure
4.2.1 General
The exposure is the challenge presented to the wood material or product and comprises many features.
The performance of each component will deteriorate or improve at a rate depending on climate, use class,
design, quality of installation, maintenance and usage.
4.2.2 Climate
The geographical location indicates the local climate and most significantly for wood products in UC 3
(e.g. exterior wood cladding) the moisture availability, as well as solar UV radiation, which can impact on
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the rate of deterioration. The geographical location also determines whether biological hazards are likely
to be present or not (e.g. termites).
Furthermore, consideration should be given to the micro-climate in service (e.g. accumulation of
condensation under a waterproof roof covering). The possibility to estimate the moisture situation (e.g.
hygrothermal simulations) should follow EN 15026.
4.2.3 Use class
The service situations in which wood is exposed to different environments and the corresponding
likelihood of susceptibility to biological degradation have been divided into use classes which are defined
in EN 335. Guidance on the application of these use classes to solid wood is given in EN 335. (See
ISO 15686-8:2008, Annex A, Clauses A.1.5 Factor D – Factor category – indoor environment and A.1.6
Factor E — Factor category: outdoor environment).
4.2.4 Design
The design detailing and workmanship of the wood material in a component has a significant impact on
the performance of the component. Poor design features that enable water trapping increase exposure
and can accelerate degradation whilst good design that excludes moisture ingress and/or easily allows
redrying during the service life of the component can reduce exposure and avoid degradation. National
guidelines for product categories should be referred to for best practice design features. (See
ISO 15686-8:2008, Annex A, Clause A.1.3 Factor B — Factor category: design level).
Enhancing performance by design means taking planning, constructive, building physics and
organizational measures which prevent or limit a reduction in the functionality of wood and wood-based
materials, especially by fungi, insects or marine borers during their service life, and also prevent damage
from excessive swelling and shrinkage of the wood and wood-based materials.
Some of these measures are enshrined in national building guidelines. These measures include restricton
or limitation of access of humidity, insects or marine borers to wood and wood-based materials e.g. by
covering or coating, calculations or simulations of moisture subject to climate conditions and protection
against undesirable changes in the moisture content of the materials during storage, transport, assembly
and installation.
In many cases, the desired performance of any measures adopted can only be ensured if the measures
and the wood component are maintained to an appropriate level (4.2.6).
4.2.5 Quality of installation
The activity of installing a wood product into service is known to have an impact on performance and
national best practice construction site guidance should be available. (See ISO 15686-8:2008, Annex A,
Clause A.1.4 Factor C — Factor category: work execution level).
4.2.6 Maintenance
Maintenance is the combination of technical, administrative and organizational measures during the
service life of an object, which serve to maintain or restore its functional condition so that it can fulfil the
required function. In many end uses, maintenance can significantly extend service life. Statements
concerning service life or requirements of durability for wood materials and wood products can only be
based on maintained buildings.
Basic measures of maintenance are regular servicing (e.g. cleaning of surfaces and gutters), inspection,
repair and improvement. A typical maintenance schedule, depending on the exposure and the actual
component, could be:
— servicing and cleaning in specific intervals depending on 4.2.2, 4.2.3, 4.2.4, 4.2.7 and Annex A;
— inspection by the user or owner when servicing and cleaning;
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— professional inspection in specific intervals depending on 4.2.2, 4.2.3, 4.2.4, 4.2.7 and Annex A;
— repair following inspection, e.g. for an exterior wood coating this might be a 5 year (2-7 years
depending on exposure) redecoration cycle;
— improvement whenever necessary.
Regular inspection of wooden components can lead to the early detection of any detrimental changes,
damage or consequential damage. The earlier changes or damage are detected, the lower the effort
required to repair consequential damage and the lower the cost of repairs or other conservation
measures.
Servicing includes maintaining the functionality of system parts, built-in parts and components, such as
coatings, drainage devices, ventilation, covers and enclosures. Servicing also includes the removal of dirt
deposits, growth of plants, moss and algae that can cause detrimental wetting of the wooden component.
Products in exterior use that are coated require coatings to be maintained to continue to provide a
protective effect to the wood material used in the product. The coating reduces the exposure of the wood
material and delays or avoids degradation. Poorly maintained coatings can exacerbate moisture risk
through water trapping. (See ISO 15686-8:2008, Annex A, Clause A.1.8 Factor G — Factor category:
maintenance level).
4.2.7 Usage
The operation of the building or asset can impact on performance (e.g. a vacant, unheated house can have
moisture and maintenance issues). (See ISO 15686-8:2008, Annex A, Clause A.1.7 Factor F — Factor
category: usage conditions).
4.3 Consequence of failure
Consequence of failure (COF) is an important element when considering service life of components.
Where there exists a high COF in service, for example where diminishing of the mechanical characteristics
of a wooden component would compromise safety and/or economic requirements, a timber of a greater
durability than normally indicated should be specified and/or the design of the component should be
optimized. This can be appropriate where:
— the components to be used are load-bearing;
— the components are difficult to replace or repair.
Taking COF into account increases the factor of safety in critical timber assemblies in buildings and other
structures of an essential nature.
Although different components can fall into the same use class, the consequence of failure can be
different, and this should, where possible, be considered in accordance with a recognized framework. An
example is presented in Annex A.
4.4 Service life
4.4.1 General
Service life is the period of time after installation during which a building, structure or component parts
meet or exceed the performance requirements. Considerations of service life can be found in national
guidance, where specific features of national wood use, direct experience and expectations are
considered. Indications of years for the definition of short, medium and long service life from published
sources are given in Table 1. Regional or national guidance should be developed to support this
framework to take into account any regional or national features of material use, design and experience
that impact on service lives of wood products.
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EN 460:2023 (E)
Table 1 — Indicative design life (EN 1990) and service life sources in years
Short Medium Long
EN 1990 < 15 30 > 50
BS 8417 15 30 60
DIN 68800-1 < 10 < 30 > 30
FD P20-651 < 10 10–50 > 50
Service life information, using design life of components and structures, can be found in EN 1990:2002,
Table 2.1 and ISO 15686-1:2011, Table B.1.
4.4.2 Limit state
An important aspect of service life is when the product has reached the limit state; its end of life which
includes ultimate and serviceability limit state. This can be different for different products and tolerances
vary amongst building and product owners.
4.5 Materials
4.5.1 General
Exposure can be minimized by measures applied in the final product such as best practice design. This
can significantly enhance performance of the final wood product (4.2.4). Protection by design to exclude
moisture (including, where valid, use of coatings) or insects to meet service life is the first consideration.
Service life in more challenging use classes may be beyond what can be confidently obtained by natural
durability or best practice design. Consideration should then be given to conferred durability.
In addition to the effects of exposure, the performance of each component will deteriorate at a rate
depending on material properties and the interface with other materials. (See ISO 15686-8:2008,
Annex A, Clause A.1.2 Factor A — Factor category: inherent performance level). For wood and wood-
based materials the following are relevant.
4.5.2 Natural durability
A classification of the durability of solid wood when subject to degradation by various wood-destroying
organisms is given in EN 350. A test method for assessing the natural durability of wood-based materials
is also given. For wood species, durability class refers only to heartwood, and sapwood is always regarded
as not durable. If a range of durability classes is given in EN 350 against the relevant organisms, the lowest
durability class should be assumed, unless the wood is of a known provenance with proven durability.
If the proportion of sapwood present is such that its loss would have adverse implications for the
performance of the component, or if the sapwood and heartwood cannot be distinguished, the durability
of the whole component should be regarded as equivalent to that of the sapwood.
4.5.3 Conferred durability
4.5.3.1 General
In some cases, the natural durability of a chosen wood species will be sufficient to meet service life
expectations. If the natural durability of the chosen species is inadequate, a means to enhance durability,
e.g. impregnation with wood preservatives, or a wood modification process shall be considered. It is
essential for wood containing sapwood that it is treated to an extent that is appropriate for the critical
biological hazard or hazards present.
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SIST EN 460:2023
EN 460:2023 (E)
When specifying wood or wood-based material, a short service life should not require over-specification
of durability or preservative treatment: taking into account the consequence of failure, a fit for purpose
decision-making principle should be in place.
4.5.3.2 Wood preservation
The specification of wood preservatives is based on EN 351-1 and EN 599-1 with additional info
...
SLOVENSKI STANDARD
oSIST prEN 460:2022
01-februar-2022
Trajnost lesa in lesnih izdelkov - Naravna trajnost masivnega lesa - Zahteve po
trajnosti lesa, ki se uporablja v posameznih razredih ogroženosti
Durability of wood and wood-based products - Natural durability of solid wood - Guide to
the durability requirements for wood to be used in hazard classes
Dauerhaftigkeit von Holz und Holzprodukten - Natürliche Dauerhaftigkeit von Vollholz -
Leitfaden für die Anforderungen an die Dauerhaftigkeit von Holz für die Anwendung in
den Gefährdungsklassen
Durabilité du bois et des matériaux dérivés du bois - Durabilité naturelle du bois massif -
Guide d'exigences de durabilité du bois pour son utilisation selon les classes de risque
Ta slovenski standard je istoveten z: prEN 460
ICS:
79.040 Les, hlodovina in žagan les Wood, sawlogs and sawn
timber
oSIST prEN 460:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 460:2022
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oSIST prEN 460:2022
DRAFT
EUROPEAN STANDARD
prEN 460
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2021
ICS 79.040 Will supersede EN 460:1994
English Version
Durability of wood and wood-based products - Natural
durability of solid wood - Guide to the durability
requirements for wood to be used in hazard classes
Durabilité du bois et des matériaux dérivés du bois - Dauerhaftigkeit von Holz und Holzprodukten -
Durabilité naturelle du bois massif - Guide d'exigences Natürliche Dauerhaftigkeit von Vollholz - Leitfaden für
de durabilité du bois pour son utilisation selon les die Anforderungen an die Dauerhaftigkeit von Holz für
classes de risque die Anwendung in den Gefährdungsklassen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 38.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 460:2021 E
worldwide for CEN national Members.
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Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Performance . 7
4.1 General . 7
4.2 Exposure . 8
4.2.1 Climate . 8
4.2.2 Use class . 9
4.2.3 Design . 9
4.2.4 Quality of site work . 9
4.2.5 Maintenance . 9
4.2.6 Usage . 10
4.3 Service life . 10
4.3.1 Limite state . 11
4.4 Consequence of failure . 11
4.5 Materials . 11
4.5.1 Natural durability . 11
4.5.2 Conferred durability . 11
4.5.3 Guidelines . 12
5 Requirements on biological durability in different end use conditions . 12
5.1 General . 12
5.2 Durability against wood-destroying fungi . 13
5.3 Durability against beetles . 13
5.4 Durability against termites . 13
5.5 Durability against marine borers . 13
5.6 Durability against combined biological hazards . 13
Annex A (informative) Consequence of Failure (COF) . 14
Annex B (informative) Example of durability classes of wood species in use class . 16
Annex C (informative) Important factors in the relationship between expected service life
and biological durability . 18
Bibliography . 21
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European foreword
This document (prEN 460:2021) 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 document is currently submitted to the CEN Enquiry.
This document will supersede EN 460:1994.
The main technical changes compared to the previous edition EN 460:1994 are the introduction of a
decision process for performance specification of wood and wood-based products based on (i) materials
and exposure, (ii) presentation of design life and (iii) articulation of consequence of failure.
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Introduction
There is increasing need to understand the service life of wood products, especially in construction.
Service life in the Construction Products Regulation: Regulation (EU) N°305/2011 (CPR) can be
understood as performance within an economically acceptable period, under typical exposure and
maintenance scenarios.
This document is concerned with the service life of wood products, especially in construction. The
purpose of this document is to provide information that will help to guide the user to select an
appropriate wood or wood-based material based on information about the end use environment and the
target service life.
In many end uses, design, workmanship and maintenance will significantly influence the service life of
the wood or wood based product.
The standard EN 350 is focused on the classification of durability of heartwood of different wood species.
In practice, wood-based building products will also contain sapwood and often different treatments, like
coatings, wood modification or wood preservation.
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1 Scope
This document gives guidance on the selection of wood of wood and wood based products for use in
situations where they may be subject to degradation by fungi or wood destroying insects. This guidance
includes information on factors that can influence the service life of a wood or wood-based product when
considering biological degradation. This document is a step toward the evaluation of the service life of a
wood product.
This document does not consider:
1) the durability characteristics of the glue used in wood-based products;
2) the aesthetic function of wood products (discoloration, surface weathering, mould).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1001-2 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
coating
surface treatment intended to provide a physical protection of the wood surface normally applied in
liquid form
3.2
component
product manufactured as a distinct unit to serve a specific function or functions
3.3
conferred durability
improved resistance of a wood species to biological degradants provided by a treatment process
(chemical, physical, etc.) such as wood preservation or wood modification
3.4
consequence of failure (COF)
the significance of the product failure in service. The outcome of a failure can be expressed in terms of
safety to personnel, economic loss, and/or damage to the environment
[SOURCE: EN 60300-3-11:2009, 3.1.23]
3.5
critical biological hazard
biological hazard or hazards that are most significant for the end use application and its geographical
location
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3.6
likelihood of failure
probability that a wood component will reach its limit state at a given time
3.7
limit state
point where a product is deemed to have failed
Note 1 to entry: The limit state is commonly reached before loss of function is complete.
3.8
material resistance
inherent ability of a material to endure a specific biological hazard through a combination of natural
and/or conferred durability and moisture dynamic behaviour relevant for the different biological agents
3.9
moisture dynamics
physical characteristic of a wood material or wood product to respond to changing environmental
conditions and take up and release moisture (vapour or liquid)
3.10
natural durability
inherent resistance of wood to attack by wood-destroying organisms
3.11
overlay
one or more sheets or films, for example impregnated paper, plastics, resin film, metal that protect a wood
surface
3.12
performance
ability of a wood species or a wood-based material to withstand deterioration over time and fulfil
essential function
3.13
permeability to water
ease with which water penetrates a wood-based matrix (wood of a particular species, wood-based
material)
Note 1 to entry: The permeability to water of a wood species or a wood-based material can be tested using the
method described in CEN/TS 16818.
3.14
service life
period of time after installation during which a building, structure or component parts meet or exceed
the performance requirements
3.15
wood modification
non-biocidal process of a chemical, biological, or physical alteration of the cell wall substance of wood,
resulting in a permanent desired property enhancement to primarily enhance biological durability and
dimensional stability
Note 1 to entry: Examples are thermal or chemical modification.
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3.16
wood preservative treatment
treatment to improve the resistance of wood to biodeterioration
Note 1 to entry: Application of wood preservative products in liquid form for the preventive treatment of wood
resulting in a desired permanent improvement of their properties in order to protect them from degradation by
wood destroying fungi, xylophagous insects (termites and beetles) or marine borers.
Note 2 to entry: The usual processes are surface treatment (soaking or spraying) or penetrating treatment
(double vacuum autoclave or vacuum autoclave and pressure).
4 Performance
When wood-destroying organisms are likely to degrade wood in service, a suitable approach for meeting
service life needs to be selected. There are principally two approaches:
1) by design - minimizing the moisture risk the wooden component is exposed to or by denying the
access for organisms through construction measures;
2) by durability - either select a wood species of sufficient natural durability or ensure sufficient
conferred durability by treatment with a wood preservative, wood modification or non-biocidal
treatment to manage the challenge presented in the use environment.
Typically it is a combination of both.
4.1 General
A schematic diagram to illustrate the performance of a wood product is shown in Figure 1. The features
defining the exposure of a material or product are multifacteted. An exposure when compared with the
service life required for the product is the framework for identifiying suitable wood and wood based
materials to meet these requirements.
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Figure 1 — Schematic illustration of a decision process for performance specification linked to
clauses in this document
This document provides information to aid the user in the choice of a wood or wood-based material for
a product, knowing its use class end use environment and the target service life. No attempt has been
made to quantify the service life that could be expected from a particular combination. This is reflected
in national interpretation documents.
4.2 Exposure
The exposure is the challenge presented to the wood material or product and comprises many features.
Building guidelines and conventionally accepted performance (4.5.3), which should be respected in the
design, often minimize the risk of a wood-destroying organism degrading wood in service. This can lead
to lower requirements concerning durability to cover the residual risk.
The performance of each component will deteriorate at a rate depending on climate, use class, design,
quality of site work, maintenance and useage.
4.2.1 Climate
The environment and particularly the moisture availability from local climate, temperature and
proximity to sea all impact on the rate of deterioration of a wood material and components. Climate data
are utilized in service prediction tools.
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4.2.2 Use class
The service situations in which wood is susceptible to biological degradation have been divided into five
use classes which are defined in EN 335. Guidance on the application of these use classes to solid wood is
given in EN 335. (See ISO 15686-8:2008, Annex A, A.1.5 Factor D – Factor category – indoor environment
and A.1.6 Factor E — Factor category: outdoor environment).
4.2.3 Design
The design detailing and workmanship of the wood material in a product has a significant impact on the
performance of the product. Poor design features that enable water trapping increase exposure and can
accelerate degradation whilst good design that excludes moisture ingress can reduce exposure and avoid
degradation. National guidelines for product categories should be referred to for best practice design
features. (See ISO 15686-8:2008, Annex A, A.1.3 Factor B — Factor category: design level).
Enhancing performance by design means taking planning, constructive, building physics and
organizational measures which prevent or limit a reduction in the functionality of wood and wood-based
materials, especially by fungi, insects or marine animals during their service life, and also prevent damage
from excessive swelling and shrinkage of the wood and wood-based materials.
Some of these measures are enshrined in national building guidelines. Others restrict or limit access of
humidity, insects or marine animals to wood and wood-based materials e.g. by covering or coating,
calculations or simulations of moisture subject to climate conditions, protection against undesirable
changes in the moisture content of the materials during storage, transport, assembly and installation.
In many cases the desired performance of any measures adopted, can only be ensured if the measures
and the wooden component is maintained to an appropriate level (4.2.5).
4.2.4 Quality of site work
The activity of installing a wood product into service is known to have an impact on performance and
national best practice construction site guidance is available. (See ISO 15686-8:2008, Annex A, A.1.4
Factor C — Factor category: work execution level).
4.2.5 Maintenance
Maintenance is the combination of technical, administrative and organizational measures during the life
cycle of an object, which serve to maintain or restore its functional condition so that it can fulfil the
required function.
Basic measures of maintenance are regular servicing (e.g. cleaning of surfaces and gutters), inspection,
repair and improvement (EN 13306). A typical maintenance schedule, depending on the exposure and
the actual component, could be:
— servicing and cleaning every half to one year;
— inspection by the user or owner when servicing and cleaning;
— professional inspection after 2-5 years in service and then annually;
— repair following inspection, e.g. for an exteriror wood coating this might be a 5 year redecoration
cycle;
— improvement whenever necessary.
In many end uses, maintenance can significantly extend service life.
Regular inspection of wooden components can lead to the early detection of any detrimental changes,
damage or consequential damage. The earlier changes or damage are detected, the lower the effort
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required to repair consequential damage and the lower the cost of repairs or other conservation
measures.
Servicing includes maintaining the functionality of system parts, built-in parts and components, such as
coatings, drainage devices, ventilation, covers, enclosures, etc. Servicing also includes the removal of dirt
deposits, growth of plants, moss and algae that may cause detrimental wetting of the wooden component.
Products in exterior use that are coated require coatings to be maintained to continue to provide a
protective effect to the wood material used in the product. The coating reduces the exposure of the wood
material and delays or avoids degradation. Poorly maintained coatings can exacerbate moisture risk
through water trapping. (See ISO 15686-8:2008, Annex A, A.1.8 Factor G — Factor category: maintenance
level).
4.2.6 Usage
The operation of the building or asset can impact on performance (e.g. high traffic areas get worn more
readily). (See ISO 15686-8:2008, Annex A, A.1.7 Factor F — Factor category: usage conditions).
4.3 Service life
Service life may be derived from national guidance, where specific features of national wood use, direct
experience and expectations are considered. Indications of years for short, medium and long service life
from published sources are given in Table 1. Regional or national guidance should be developed to
support this framework to take into account any regional or national features of material use, design and
experience that impact on service life uses of wood products. In Table 2, the suggested minimum design
service lives for building products are presented (ISO 15686-1).
Table 1 — Service life indications in years from national documents and other standards
Short Medium Long
EN 1990 <15 30 >50
BS 8417 15 30 60
DIN 68800-1 <10 <30 >30
FD P 20-651 <10 10-50 >50
Table 2 — Suggested minimum design lives for components (DLC) extract from ISO 15686-1
Design life of Inaccessible or Components where Major replaceable
building structural replacement is components
components expensive or difficult
Unlimited Unlimited 100 40
150 150 100 40
100 100 100 40
60 60 60 40
25 25 25 25
15 15 15 15
10 10 10 10
NOTE 1 Easily-replaced components may have design life of 3 to 6 years.
NOTE 2 An unlimited design life should rarely be used, as it significantly reduces design options.
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4.3.1 Limite state
An important aspect of service life is when the product has reached the limit state; its end of life. This can
be different for different products and tolerances vary amongst building and product owners.
4.4 Consequence of failure
Consequence of failure (COF) is an important element when considering service life of components.
Where there exists a high COF in service, for example where diminishing of the mechanical characteristics
of a wooden component would compromise safety and/or economic requirements, a timber of a greater
durability than normally indicated should be specified. This may be appropriate where:
— the components to be used are load-bearing;
— the components are difficult to replace or repair.
COF increases the factor of safety in critical timber assemblies in buildings and other structures of an
essential nature.
Although different components can fall into the same use class, the consequence of failure can be
different, and this should be considered in accordance with a recognized framework. An example is
presented in Annex A.
4.5 Materials
The exposure can be minimized by measures applied in the final product such as best practice design.
This can significantly enhance performance of the final wood product (4.2.3).
Alongside the exposure the performance of each component will deteriorate at a rate depending on
material properties and the interface with other materials. (See ISO 15686-8:2008, Annex A, A.1.2 Factor
A — Factor category: inherent performance level). For wood and wood-based materials the following are
relevant.
4.5.1 Natural durability
The classification for the durability of solid wood and wood-based materials to degradation by various
wood-destroying organisms are given in EN 350. For wood species, durability class refers only to
heartwood and sapwood is always regarded as not durable. If a range of durability classes is given in
EN 350 against the relevant organisms, the lowest durability class should be selected.
If the proportion of sapwood present is such that its loss would have adverse implications for the
performance of the component, or if the sapwood and heartwood cannot be distinguished, the durability
of the whole component should be regarded as equivalent to that of the sapwood.
4.5.2 Conferred durability
In some cases, the natural durability of a chosen wood species will be sufficient to meet service life
expectations. If the natural durability of the chosen species is inadequate, a means to enhance durability,
e.g. impregnation with wood preservatives, or a wood modification process must be considered. It is
essential for wood containing sapwood that it is treated to an extent that is appropriate for the critical
biological hazard or hazards present.
When specifying wood or wood-based material, a short service life should not require over specification
of durability or preservative treatment, a fit for purpose decision making principle should be in place. In
addition, a long service life in more challenging use classes maybe beyond what can be confidently
obtained by natural durability or conferred durability. Consideration should be given to protection by
design to exclude moisture (including, where valid, use of coatings) to meet service life.
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4.5.2.1 Wood preservation
The specification of wood preservatives is based on EN 351-1 and EN 599-1 with additional information
on treatability in EN 350. This document gives guidance on where preservative treatment, wood
modification or enhancing performance by design may be necessary.
4.5.2.2 Wood modifications
This specification of wood modification technologies is based on EN 350 and complemented by moisture
dynamics as part of material resistance. The use of natural durability and conferred durability using wood
modification links use classes to durability classes, based on a fit for purpose approach and taking into
account the variability of durability class rating. The approach should limit reliance on very durable wood
species in situations where it is not necessary, eg UC 1 and 2.
4.5.3 Guidelines
Material that conforms to regionally accepted performance guidelines (national or European standards)
or according to conventionally accepted performance (craftsmen guidelines) is another route to selecting
an appropriate material.
5 Requirements on biological durability in different end use conditions
5.1 General
The ability of wood or a wood-based material to achieve a particular service life will depend, in part, on
the durability of that material. Durability against the following should be taken into consideration: fungi,
termites, wood-boring beetles and marine borers. The durability to each of these biological agents should
be considered separately.
For each product application, the performance against biological agents needs to be considered, and the
critical biological hazard should be identified. Table 3 indicates the critical biological hazard in each use
class and shows the importance of basidiomycetes fungi.
Table 3 — Critical biological hazards for each use class
Basidiomycetes Soft rot a Beetles Marine
Termites
borers
UC1 - - X X -
UC2 X - X X -
UC3 X - X b -
X
UC4 X X X - -
UC5 c c - - X
X X
a
Specific regions of Europe only.
b
Lower impact of insects in outdoor environment.
c
Above waterline section only.
The following sections consider the biological hazards which, on consideration of the region and use class,
may represent the critical biological hazard.
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5.2 Durability against wood-destroying fungi
The requirement for durability of a wooden component depends on many factors, particularly use class,
the macro- and micro-climate where the component is used and/or by design detailing that can reduce
moisture levels to those unfavourable to decay fungi. A national or regional climate that results in lower
or higher risk of decay can result
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