SIST EN 338:2004

SLOVENSKI STANDARD
SIST EN 338:2004
01-januar-2004
1DGRPHãþD
SIST EN 338:1996
Konstrukcijski les - Trdnostni razredi
Structural timber - Strength classes
Bauholz für tragende Zwecke - Festigkeitsklassen
Bois de structure - Classes de résistance
Ta slovenski standard je istoveten z: EN 338:2003
ICS:
79.040 Les, hlodovina in žagan les Wood, sawlogs and sawn
timber
SIST EN 338:2004 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 338:2004

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SIST EN 338:2004
EUROPEAN STANDARD
EN 338
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2003
ICS 79.040 Supersedes EN 338:1995
English version
Structural timber - Strength classes
Bois de structure - Classes de résistance Bauholz für tragende Zwecke - Festigkeitsklassen
This European Standard was approved by CEN on 14 February 2003.
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 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 Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2003 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 338:2003 E
worldwide for CEN national Members.

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SIST EN 338:2004
EN 338:2003 (E)
Contents
page
Foreword.3
Introduction .4
1 Scope .4
2 Normative references .4
3 Terms and definitions.5
4 Symbols and abbreviations .5
5 Classification of structural timber.5
6 Allocation of a timber population to a strength class.8
6.1 Grading .8
6.1.1 Visually graded timber .8
6.1.2 Machine graded timber.8
6.2 Classification.8
6.2.1 Characteristic values.8
6.2.2 Allocation to a strength class.8
Annex A (informative) Equations for characteristic values .9
Bibliography .10
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SIST EN 338:2004
EN 338:2003 (E)
Foreword
This document (EN 338:2003) has been prepared by Technical Committee CEN/TC 124 "Timber structures", the
secretariat of which is held by DS.
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 October 2003, and conflicting national standards shall be withdrawn at the latest
by October 2003.
This document supersedes EN 338:1995.
Annex A is informative.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal,
Slovakia, Spain, Sweden, Switzerland and the United Kingdom.
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SIST EN 338:2004
EN 338:2003 (E)
Introduction
This revised edition has additional strength classes and lists the equations, formerly in EN 384, that form the
relations between some of the characteristic values. Changes have also been made to some of the characteristic
values and the requirements for assigning grades and species to strength classes.
Due to variations in the type and quality of timber available, the variety of end uses and the size of production
output of the local timber industry, many different combinations of species and strength grade exist with different
strength properties, which therefore complicate the design and specification of timber structures.
A strength class system groups together grades and species with similar strength properties thus making them
interchangeable. This then permits an engineer to specify a chosen strength class and use the characteristic
strength values of that class in design calculations.
Advantages of the strength class system are:
- Additional species/grades can be incorporated into the system at any time without affecting existing
specifications for structural timber.
- At the time of carrying out design calculations, an engineer need not be aware of the costs and availability
of alternative species and grades. He can simply design using the strength values of a particular class
and then specify that class; he can then use the tenders to select the most suitable and economic
species/grade on offer. Note that, where a particular species is not acceptable (e.g. for reasons of
durability) for a project, the specification needs to make this clear.
- Suppliers can offer their material to meet more specifications than would be possible if species and
grades were specified.
1 Scope
This standard establishes a system of strength classes for general use in structural codes.
It gives characteristic strength and stiffness properties a
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