oSIST prEN 14081-1:2012

SLOVENSKI STANDARD
oSIST prEN 14081-1:2012
01-september-2012
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Timber structures - Strength graded structural timber with rectangular cross section -
Part 1: General requirements
Holzbauwerke - Nach Festigkeit sortiertes Bauholz für tragende Zwecke mit
rechteckigem Querschnitt - Teil 1: Allgemeine Anforderungen
Structures en bois - Bois de structure à section rectangulaire classé pour sa résistance -
Partie 1: Exigences générales
Ta slovenski standard je istoveten z: prEN 14081-1 rev
ICS:
79.040 Les, hlodovina in žagan les Wood, sawlogs and sawn
timber
91.080.20 Lesene konstrukcije Timber structures
oSIST prEN 14081-1:2012 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 14081-1:2012

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oSIST prEN 14081-1:2012


EUROPEAN STANDARD
DRAFT
prEN 14081-1 rev
NORME EUROPÉENNE

EUROPÄISCHE NORM

May 2012
ICS 79.040 Will supersede EN 14081-1:2005+A1:2011
English Version
Timber structures - Strength graded structural timber with
rectangular cross section - Part 1: General requirements
Structures en bois - Bois de structure à section Holzbauwerke - Nach Festigkeit sortiertes Bauholz für
rectangulaire classé pour sa résistance - Partie 1: tragende Zwecke mit rechteckigem Querschnitt - Teil 1:
Exigences générales Allgemeine Anforderungen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 124.

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, Romania, 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

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 14081-1 rev:2012: E
worldwide for CEN national Members.

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prEN 14081-1:2012 (E)
Contents Page
Foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Symbols . 9
5 Requirements for structural timber . 9
5.1 Strengths, modulus of elasticity and density . 9
5.1.1 General on grading . 9
5.1.2 Visual strength grading . 9
5.1.3 Machine strength grading . 9
5.2 Dimensional stability . 11
5.3 Fire resistance R . 11
5.4 Reaction to fire . 11
5.5 Durability against biological attack . 12
5.5.1 Timber without preservative treatment . 12
5.5.2 Timber with preservative treatment . 12
6 Evaluation of conformity . 12
6.1 General . 12
6.2 Initial Type Testing – Type Testing . 12
6.2.1 General . 12
6.2.2 Test samples, testing and compliance criteria . 13
6.2.3 Test reports . 14
6.3 Factory production control (FPC) . 14
6.3.1 General . 14
6.3.2 Requirements . 14
6.3.3 Product specific requirements . 16
6.3.4 Initial inspection of factory and of FPC . 17
6.3.5 Continuous surveillance of FPC . 17
6.3.6 Procedure for modifications . 18
7 Marking, labelling and packaging . 18
7.1 General . 18
7.2 Information either on the timber (method A) or on its package (method B) . 18
7.3 Information in the documents accompanying either the timber or package of such
timber . 19
Annex A (normative) Requirements for strength reducing characteristics for visual grading
standards . 23
A.1 Limitations for strength-reducing characteristics . 23
A.1.1 Knots . 23
A.1.2 Slope of grain . 23
A.1.3 Density and rate of growth . 23
A.1.4 Fissures. 24
A.2 Limitations for geometrical characteristics . 24
A.2.1 Wane . 24
A.2.2 Warp . 24
A.3 Limitations for biological characteristics . 25
A.4 Other characteristics . 25
A.4.1 Reaction wood . 25
A.4.2 Other criteria . 25
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Annex B (informative) Marking codes for single species . 26
Annex ZA (informative) Clauses of this European Standard addressing the provisions of the EU
Construction Products Directive . 28
ZA.1 Scope and relevant characteristics . 28
ZA.2 Procedure for attestation of conformity of strength graded structural timber with
rectangular cross section . 30
ZA.2.1 Systems of attestation of conformity . 30
ZA.2.2 EC Certificate and Declaration of conformity . 31
ZA.3 CE marking and labelling . 32
ZA.3.1 General . 32
ZA.3.2 Simplified CE marking . 32
ZA.3.3 Complete CE marking . 33

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oSIST prEN 14081-1:2012
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Foreword
This document (prEN 14081-1:2012) has been prepared by Technical Committee CEN/TC 124 “Timber
Structures”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 14081-1:2005+A1:2011.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive.
For relationship with EU Directive, see informative Annex ZA, which is an integral part of this document.
Other parts of the series of EN 14081 are:
EN 14081-2, Timber structures - Strength graded structural timber with rectangular cross section - Part 2:
Machine grading; additional requirements for initial type testing,
EN 14081-3, Timber structures - Strength graded structural timber with rectangular cross section - Part 3:
Machine grading; additional requirements for factory production control,
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Introduction
There are basically two methods of strength grading: visual grading and machine grading.
Machine grading is in common use in a number of countries. The countries use two basic systems, referred
to as 'output controlled' and 'machine controlled'. Both systems require a visual override inspection to cater
for strength-reducing characteristics that are not automatically sensed by the machine. The output-
controlled system is suitable for use where the grading machines are situated in sawmills grading limited
sizes, species and grades in repeated production runs. This enables the system to be controlled by testing
timber specimens from the daily output. These tests together with statistical procedures are used to monitor
and adjust the machine settings to maintain the required strength properties for each strength class. With
this system it is permissible for machine approval requirements to be less demanding and for machines of
the same type to have non-identical performance.
The machine controlled system was developed in Europe. Because of the large number of sizes, species
and grades used it was not possible to carry out quality-control tests on timber specimens drawn from
production. The system relies therefore, on the machines being strictly assessed and controlled, and on
considerable research effort to derive the machines settings, which remain constant for all machines of the
same type.
Visual grading is also in common use in a number of countries. There are many different visual strength
grading rules for timber in use in Europe. These have come into existence to allow for:
 different species or groups of species;
 geographic origin;
 different dimensional requirements;
 varying requirements for different uses;
 quality of material available;
 historic influences or traditions.
Because of the diversity of existing visual grading rules in use in different countries, it is currently impossible
to lay down a single set of acceptable rules for all Member States.
The requirements given in this European Standard on visual strength grading rules therefore give basic
principles, which should be followed when drawing up requirements for limits for some of the
characteristics.
The accepted assignments to strength classes are based on approved grading reports (AGR).
In most cases, the AGR's have been evaluated by CEN/TC124/WG2/TG1, which is the basis for the attestation
of conformity by the Notified Body conducting the certification of the producer’s factory production control
(FPC) needed for the CE marking.
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1 Scope
This European Standard specifies the requirements for visual and machine graded structural timber with
rectangular cross-sections shaped by sawing, planning or other methods, and having minimum dimensions
complying with EN 336.
This European Standard consists of provisions for test methods, evaluation of conformity (ITT and FPC)
and marking of both grading types of structural timber.
NOTE For the machine graded timber additional provisions for ITT are given in EN 14081-2 and for FPC in EN
14081-3.
This European Standard identifies as a minimum the characteristics for which limits are given in visual
grading rules.
This European Standard covers structural rectangular timber, untreated or treated against biological attack.
This European Standard does not cover timber treated by fire retardant products to improve its fire
performance.
Finger jointed timber made of rectangular cross-sections is not covered in this European Standard.
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 335-1, Durability of wood and wood-based products — Definition of use classes — Part 1: General
EN 335-2, Durability of wood and wood-based products — Definition of use classes — Part 2: Application to
solid wood
EN 336, Structural timber — Sizes, permitted deviations
EN 338, Structural timber — Strength classes
EN 350-1, Durability of wood and wood-based products — Natural durability of solid wood — Part 1: Guide
to the principles of testing and classification of the natural durability of wood
EN 350-2, Durability of wood and wood-based products — Natural durability of solid wood — Part 2: Guide
to natural durability and treatability of selected wood species of importance in Europe
EN 384, Structural timber — Determination of characteristic values of mechanical properties and density
EN 844-7, Round and sawn timber — Terminology — Part 7: Terms relating to anatomical structure of
timber
EN 844-9, Round and sawn timber — Terminology — Part 9: Terms relating to features of sawn timber
EN 844-10, Round and sawn timber — Terminology — Part 10: Terms relating to stain and fungal attack
EN 1310:1997, Round and sawn timber — Method of measurement of features
EN 1912:2004+A4:2010, Structural timber — Strength classes — Assignment of visual grades and species
EN 1995-1-2, Eurocode 5 –Design of timber structures – Part 1-2: General – Structural fire design
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EN 13183-2, Moisture content of a piece of sawn timber — Part 2: Estimation by electrical resistance
method
EN 13183-3, Moisture content of a piece of sawn timber — Part 3: Estimation by capacitance method
EN 13238, Reaction to fire tests for building products — Conditioning procedures and general rules for
selection of substrates
EN 13501-1:2007+A1:2009, Fire classification of construction products and building elements — Part 1:
Classification using test data from reaction to fire tests
EN 13501-2:2007+A1:2009, Fire classification of construction products and building elements — Part
2:Classification using data from fire resistance tests, excluding ventilation services
EN 13556, Round and sawn timber — Nomenclature of timbers used in Europe
EN 13823, Reaction to fire tests for building products — Building products excluding floorings exposed to
the thermal attack by a single burning item
EN 14081-2, Timber structures — Strength graded structural timber with rectangular cross section — Part 2:
Machine grading; additional requirements for initial type testing
EN 14081-3, Timber structures — Strength graded structural timber with rectangular cross section — Part 3:
Machine grading; additional requirements for factory production control
EN 15228:2009, Structural timber — Structural timber preservative treated against biological attack
EN ISO 3166-1, Codes for the representation of names of countries and their subdivisions — Part 1:
Country codes (ISO 3166-1)
3 Terms and definitions
For the purposes of this European Standard, the following terms and definitions apply.
3.1
batch
timber of one species, species combination, population and size graded in one working shift. In the case of
machine graded timber, the timber should also be graded by one machine.
3.2
characteristic strength
population 5-percentile value obtained from the results of tests with a duration of (300 ± 120) s using test
pieces at an equilibrium moisture content resulting from a temperature of 20 °C and a relative humidity of 65
%
3.3
control plank
object that simulates the characteristics of timber that are being sensed by the measuring devices in a
grading machine, which, when passed through the machine, is able to check the calibration of the machine
dynamically
3.4
dry-graded timber
timber that is part of a batch that has intentionally been graded at a mean moisture content of 20 % or less,
without any measurement exceeding 24 %
3.5
grade
strength grade or strength class
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3.6
machine strength grading
process by which a piece of timber can be sorted by a machine sensing, non-destructively, one or more
properties of the timber, with any necessary visual overriding inspection, into grades to which characteristic
values of strength, stiffness and density may be allocated. There are two methods of control, machine
control and output control (see Introduction)
3.7
package
timber
- of one grade,
- of one species or species combination,
- of one cross section size or of multiple sizes where the timber is to be used for one structure,
- graded in one working shift
- to be delivered to one customer
3.8
producer
legal entity responsible for the conformity of the product to the requirements of this European Standard
3.9
settings
values associated with the variable controls of a grading machine which determine the acceptance to each
grade of timber graded by the machine
3.10
strength class
result of the classification of structural timber based on particular values of its mechanical properties and
density
3.11
strength-reducing characteristic
property or feature of a piece of timber that reduces its load bearing capacity
Note 1 to entry: Can result from natural growth of the tree (e.g. knots, slope of grain), changes in moisture content
(e.g. fissures), conversion of the log (e.g. the inclusion of wane), attack from fungi, insects or mechanical damage.
3.12
timber population
timber from an identifiable source and of a species or species combination that is, or is intended to be,
strength graded and marketed as a commercially defined product
3.13
timber size
sawn or processed dimensions with respect to the permitted deviations given in EN 336
3.14
visual strength grading
process by which a piece of timber can be sorted, by means of visual inspection, into a grade to which
characteristic values of strength, stiffness and density may be allocated
Note 1 to entry: Electronic or mechanical instruments can be used to assist the visual grader in this process.
3.15
width
greater dimension perpendicular to the longitudinal axis of a piece of timber
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4 Symbols
None.
5 Requirements for structural timber
5.1 Strengths, modulus of elasticity and density
5.1.1 General on grading
Structural timber, shall be either visually graded according to 5.1.2 or machine graded according to 5.1.3,
and have characteristic values for the edgewise bending strength, tension strength, compression strength,
shear strength, modulus of elasticity and density according to the method given in 5.1.2 or 5.1.3.
If the grading has been carried out before processing, provided that the processing reduction is not greater
than 5 mm for dimensions less than or equal to 100 mm, or not greater than 10 mm for dimensions greater
than 100 mm, the grade shall be considered not to have changed. If the reduction is greater, the timber
shall be re-graded.
Moisture content shall be determined in accordance with EN 13183-2 or EN 13183-3. The accuracy of
moisture meter shall be ± 2 %.
If the grading method restricts the timber to a special use, e.g. flatwise bending or compression, the timber
shall be marked accordingly.
5.1.2 Visual strength grading
Timber shall be graded visually in accordance to a national grading standard that meets the requirements
given in Annex A.
If the grade and species have been assigned to a strength class by EN 1912, the characteristic values for
the properties shall be those given for the assigned strength class in EN 338; otherwise they shall be
determined in accordance with EN 384.
If there are any restrictions or additional criteria related to the strength or constructional use of timber,
resulting from the method of grading or species of timber, they shall be stated in the grading standard.
5.1.3 Machine strength grading
If the timber is machine graded to a strength class from EN 338, the characteristic values for the properties
shall be those given for the strength class in EN 338; otherwise they shall be determined in accordance with
EN 384.
For a grade and species (or species combination) graded by a machine controlled system, the settings shall
be derived for the total growth area from which the timber will be graded within one or more countries.
Grading machines shall use settings determined in accordance with EN 14081-2. Grading machines and
settings used in machine controlled system shall be evaluated by CEN/TC124. Accepted settings shall be
documented in Approved Grading Reports (AGR).
NOTE Approved Grading Reports are intended to give basic documentation for the certification by a Notified Body
of a producer's factory production control (FPC) needed for the CE marking. An updated list of AGRs may be obtained
through CEN/TC124.
The visual characteristics of each piece of machine graded timber shall meet the requirements given in
Table 1.

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Table 1 — Visual override inspection requirements for machine strength graded structural timber
Strength class acc. to EN 338 C18 and below Above C18
Fissures not Fissures less than half the thickness may be ignored e
going through

Not greater than 1,5 m or ½ the length Not greater than 1 m or ¼ the
the thickness
of the piece, whichever is the lesser length of the piece, whichever
Max. length
a is the lesser
of fissures
Fissures going Not greater than 1 m or ¼ the length of Only permitted at the ends with
through the the piece, whichever is the lesser. If at a length not greater than the
thickness the ends, a length not greater than two width of the piece
times the width of the piece

Bow 20 mm 10 mm
b
Max. warp
Spring 12 mm 8 mm
in mm over
Twist 2 mm/25 mm width 1 mm/25 mm width
2 m of length
Cup Unrestricted Unrestricted
Wane Wane shall not be greater than one third of the full edge and/or face
dimensions of the piece
Soft rot and Soft rot shall not be permitted. Soft rot shall not be permitted.
c
dote (see
Dote is permitted Dote shall not be permitted
EN 844-10)
Insect Active infestation shall not be permitted. Wood wasp holes shall not be
damage permitted and worm and pin holes shall be assessed as other defects
Other Where the reduction in strength caused by the other defect is obviously less
defects than caused by defects permitted by this table, the piece may be accepted
provided the defect is of a type that will not increase after conversion and
drying
a The length of fissures is linked with moisture content and therefore the limits given apply only at the time of grading.
As a consequence of this, the moisture content at the time of grading should be appropriate to the end-use.
Permitted limits for both the depth and length of fissures refer to the sum of fissures in one plane in a piece of timber.
b Warp is influenced by moisture content, so the limits apply only at the time of grading. As a consequence of this ,
the moisture content at the time of grading should be appropriate to the end-use. Longitudinal curvature in square
section pieces may be assessed using the limits for bow.
c Stain is not a structural defect and is acceptable without limitation.
d Other defects include for example mechanical damage, top rupture, included bark
e A 0.2 mm feeler gauge is a suitable device for measuring fissure depth


Where a machine does not fully grade to the ends of each piece of timber (as in bending type machines)
these non-fully graded portions shall be visually examined. If the diameter of knots and slope of grain in the
non-fully graded portions exceeds the size of such defects exceeds the limits given in Table 2, then the
piece of timber shall be rejected. Knots and slope of grain shall be measured in accordance with EN 1310.
Timber that has previously been graded shall not be re-graded to the same or different grades unless the
method of determining settings has made
...