prEN 14544

Timber structures - Strength graded structural timber with round cross-section - Requirements

This European Standard lays down the requirements for visual graded structural timber with round cross-sections, barked of unbarked and cut on length but otherwise not machined.
This standard specifies tolerances on sizes and identifies the characteristics for which, as a minimum, limits shall be given in visual grading rules. It also proposes two grades recommended where no national grades exist.
Structural timber treated against fire or biological attack is not covered in this standard.

Holzbauwerke - Festigkeitssortiertes Rundholz für tragende Zwecke - Anforderungen

Diese Europäische Norm legt die Anforderungen an visuell sortiertes Rundholz mit oder ohne Rinde, das abgelängt jedoch sonst unbearbeitet ist, fest.
Diese Norm legt zulässige Maßabweichungen sowie diejenigen Merkmale fest, für die in den visuellen Sortierregeln Mindestwerte anzugeben sind. Darin werden ebenfalls zwei Sortierklassen für die Fälle, wo keine nationalen Sortierklassen bestehen, vorgeschlagen.
Bauholz, das zum Schutz gegen Feuer oder biologischen Befall behandelt wurde, ist nicht Gegenstand dieser Norm.

Structures en bois - Classement des bois de structure à section transversale ronde selon la résistance - Exigences

La présente norme européenne stipule les exigences relatives au classement visuel, selon la résistance, du bois de structure à sections transversales rondes, écorcé ou non et coupé sur la longueur mais non usiné.
La présente norme spécifie les tolérances dimensionnelles et identifie les caractéristiques pour lesquelles des limites minimales doivent être indiquées dans les règles de classement visuel. Elle recommande également deux classes lorsque aucune classe nationale n'existe.
La présente norme ne traite pas du bois de structure ayant subi un traitement contre le feu ou les attaques biologiques.

Lesene konstrukcije - Konstrukcijski les z okroglimi fazonskimi kosi - Zahteve

General Information

• Status: Not Published
• ICS: 79.040 - Wood, sawlogs and sawn timber
• ICS: 91.080.20 - Timber structures
• Technical Committee: CEN/TC 124 - Timber structures
• Drafting Committee: CEN/TC 124/WG 2 - Solid timber
• Current Stage: 4060 - Closure of enquiry - Enquiry
• Due Date: 19-Mar-2003
• Completion Date: 19-Mar-2003
• Mandate: M/112 - Mandate to CEN/CENELEC concerning the execution of standardization work for harmonized standards on structural timber products
• Ref Project: oSIST prEN 14544:2006 - Timber structures - Strength graded structural timber with round cross-section - Requirements

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EUROPEAN STANDARD
DRAFT
prEN 14544
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2006
ICS 91.080.20; 79.040

English Version
Timber structures - Structural timber with round cross-section -
Requirements
Structures en bois - Bois de structure à section ronde - Holzbauwerke Rundholz für tragende Zwecke -
Exigences Anforderungen
This draft European Standard is submitted to CEN members for second 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 Management Centre has the same
status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, 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 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: rue de Stassart, 36  B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 14544:2006: E
worldwide for CEN national Members.

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prEN 14544:2006 (E)
Contents Page
Foreword .3
1 Scope.3
2 Normative references.3
3 Terms and definitions .4
4 Symbols and abbreviations.7
5 Requirements.7
6 Evaluation of conformity .8
7 Marking.11
Annex A (normative) Reaction to fire: Euroclass without the need for further testing.13
B.3.1 Biological attacks.16
B.3.3 Included sapwood .16
Clauses of this European Standard addressing the provisions of the EU Construction
Products Directive.17
An example of a mark on the product is given in Figure ZA.1. .21

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prEN 14544:2006 (E)
Foreword
This document (prEN 14544:2006) has been prepared by Technical Committee CEN/TC 124 “Timber
structures”, the secretariat of which is held by SFS.
This document is currently submitted to the second CEN Enquiry.
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(s).
For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this
document.
1 Scope
This European Standard specifies the requirements for visual graded structural timber with round
cross-sections, barked or unbarked and cut to length.

The standard covers timber untreated or treated against biological attack.

The standard does not cover timber treated by fire retardant products.

The standard identifies the characteristics for whish as a minimum limits shall be given in visual grading
rules

2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places in the text and the publications are
listed hereafter. For dated references, subsequent amendments to or revisions of any of these
publications apply to this European Standard only when incorporated in it by amendment or revision.
For undated references the latest edition of the publication referred to applies (including amendments).

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
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prEN 14544:2006 (E)
EN 1310: 1997, Round and sawn timber - Method of measurements of features
EN 13183-2, Round and sawn timber - Method of measurement of moisture content - Part 2: Method for
estimating moisture content of a piece of sawn timber (Electrical method)
EN 13501-1, Fire Classification of construction products and building elements – Part 1: Classification
using tests from reaction to fire tests
EN 13823, Reaction to fire tests for building products – Building products excluding floorings exposed to
the thermal attack by a single burning item
EN 14251, Timber structures – Structural round timber – Determination of the strength and stiffness
parallel to grain in bending and compression
PrEN 15228, Structural timber – Structural timber treated against biological attack

ISO 8322-2, Building construction - Measuring instruments - Procedures for determining accuracy in
use - Part 2: Measuring tapes
EN/ISO 29002, Quality management systems – Requirements
3 Terms and definitions
For the purposes of this standard, the terms and definitions given in EN 385, EN 14080 and EN 14081
apply. Further the following definitions apply:

3.1 bark pocket
bark that is partly or wholly enclosed in the wood.
3.2 batch
timber of one species population and target size graded in one working shift
3.3 characteristic density
population 5-percentile value of density with mass and volume corresponding to equilibrium moisture
o
content at a temperature of 20 C and a relative humidity of 65 %

3.4 characteristic strength
population 5-percentile value of strength obtained from the results of tests with a duration of 300 s using
o
test pieces at an equilibrium moisture content resulting from a temperature of 20 C and a relative
humidity of 65 %

3.5 characteristic stiffness
population 5-percentile value or the mean value of stiffness obtained under the same test conditions as
defined in 3.3

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prEN 14544:2006 (E)
3.6 compression wood
reaction wood formed typically on lower sides of branches and of leaning or crooked stems of softwood
trees.
3.7 decay
decomposition of wood by fungi or other micro-organisms resulting in softening, progressive loss of
mass and strength, and often a change of texture and colour.
3.8 deviation
difference between actual size and the corresponding target size, making allowance for the difference in
size due to difference in moisture content

3.9 diameter
distance at the section of measurement between two parallel lines tangential to the stem of round
timber
3.10 fissure
longitudinal separation of fibres.
3.11 grade
strength grade

3.12 grade determining property
mechanical or physical property for which a particular value of that property has to be achieved for the
material to be assigned to that grade
3.13 growth rate
average number of growth rings per 25 mm.
3.14 heart shake
radial end shake originating at the pith.
3.15 included sapwood
presence in the heartwood of a complete or incomplete ring having the colour and the properties of
sapwood

3.10 knot
portion of a branch embedded in wood.

3.16 knot cluster

3.17 maximum diameter
maximum diameter at the section of measurement
3.18 minimum diameter
minimum diameter at the section of measurement
3.19 nominal diameter
a) theoretical diameter at the section of measurement for timber with 5 % or less ovality
b) minimum diameter at the section of measurement for timber with greater than 5 % ovality

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prEN 14544:2006 (E)
3.20 ovality
difference between the maximum and minimum diameter at a cross section expressed as a percentage
of the minimum diameter

3.21 producer
legal entity responsible for the grading of the timber
3.22 sample
specimens of timber of one size and representative of one species population

3.23 species 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

3.24 strength-reducing characteristic
weakness in a piece of timber resulting from natural growth of the tree (e.g. knots, slope of grain) or
changes in moisture content (e.g. fissures) or resulting from conversion of the log or caused by attack
from fungi, insects or mechanical damage

3.25 target size
size specified at the reference moisture content, and to which the deviations, which would ideally be
zero, are to be related

3.26 theoretical diameter
diameter of a circle with the same circumference as the actual circumference at the section of
measurement

3.27 timber size
sawn or processed dimensions with respect to the permitted deviations given in 5.2

3.28 visual strength grading
process by which a piece of timber can be sorted, by means of visual inspection, into grades to which
characteristic values of strength and stiffness may be allocated. Electronic or mechanical instruments
may be used to assist the visual grader in this process.

3.29 reaction wood
wood with distinctive anatomical characteristic, formed typically in parts of leaning or crooked stems
and in branches when the tree tends to restore the original position, if this has been disturbed.
3.30 rindgall
surface wound that has been partially enclosed by the growth of a tree.
3.31 ring shake
fissure following the line of a growth ring.
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prEN 14544:2006 (E)
3.32 scribe
Cranked rod with a swivel handle and a needle at the tip, set to a slight trailing angle. Used as a grain
detector by pressing the needle into the timber and drawing it across the surface in the apparent
direction of the grain.
3.33 slope of grain
divergence of the direction of the fibres from the longitudinal axis of the piece.
3.34 star shake
two or more heart shakes.
3.35 sweep
deviation of the longitudinal axis of round timber from a straight line.

3.36 taper
gradual reduction in diameter of a stem along its height or round timber along its length.
3.37 tension wood
reaction wood formed typically on upper sides of branches and of leaning or crooked stems of
hardwood trees
4 Symbols and abbreviations
d diameter (in mm)
l length (in mm)
w distortion (in mm)
5 Requirements
5.1 Sizes and tolerances
Length shall be measured using a tape measure complying with ISO 8322-2.
Diameters shall be measured under any bark using calipers. Alternatively, the theoretical diameter may
be calculated from the circumference measured by using a tape measure complying with ISO 8322-2.
Limit For the purposes of this standard the reference moisture content is 20 %. The moisture content
shall be determines according to EN 13183-2.
5.1.1 Deviations
The limit deviations on length is –0/+ 1%; however for length less than 2 m –0/+20 mm.
The limit deviations from the nominal target diameter referred to the reference moisture content and
measured at midspan/midlength under bark is –0/+20 mm.

5.1.2 Changes in size due to changes in moisture content
Unless there is evidence to the contrary, it shall be assumed that the diameter of round timber
increases by 0,25 % for every 1,0 % of moisture content higher than 20 % up to 30 %, and decreases
by 0,25 % for every 1,0 % of moisture content lower than 20 %. The above values are typical, without
regard to species.
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prEN 14544:2006 (E)

5.2 Timber
5.2.1 Grading
Timber shall be visual graded according to a grading standard that meets the requirements given in
Annex A. and have characteristic values for bending strength, compression strength, modulus of
elasticity amd density determined according to the appropriate clause in EN 14251.

Unless otherwise stated, 20 % moisture content shall be taken as the reference point for all
measurements.

5.2.2 Characteristic values
The producer shall declare characteristic values for the bending strength, compression strength,
modulus of elasticity in bending (5-percentile and mean value) and density. The declared values shall
not be greater than characteristic values found from results from testing untreated timber according to
EN 14251 evaluated in accordance with EN 384.
5.2.3 Durability against biological attack


5.2.3.1 If relevant, the producer shall declare the natural durability assessed in accordance with EN
350-1. If listed in EN 350-2, the natural durability shall be declared as given therein.
5.2.3.2   Timber treated against biological attack shall meet the requirements of prEN 15228.


5.2.4 Reaction to fire
3
Round timber with a minimum density of 350 kg/m can without further testing be classified as D-s2, d0.

3
Timber with a density below 350 kg/m shall where required, be tested and classified in accordance
with EN 13501-1.
6 Evaluation of conformity
6.1 General
Compliance with the requirement of this standard shall be demonstrated by:

- initial type testing and initial assessment,

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prEN 14544:2006 (E)
- factory production control by the producer.

All type testing reports shall be kept for at least five years after the date of last date of production of the
product to which they relate, while all Factory Production Control record shall be kept for at least five
years.

6.2 Type testing and assessment
Initial type testing shall be performed on first application of this standard. Tests previously performed in
accordance with the provisions of this standard (same product, same population, same
characteristic(s), test method, sampling procedure, system of attestation of conformity etc.) may be
taken into account.

Whenever a change occurs, e.g. in raw materials, which would change significantly one or more
characteristics, the type testing and assessment shall be repeated for the appropriate characteristic(s).

The testing and assessment shall be in accordance with Table 1.

Table 1 – Sampling plan and compliance criteria f0r initial testing
Property Requirement Method Number of Compliance criteria
specimens
Characteristic strength  See EN 14251-2 See EN 384 -2 Characteristic values
estimated according to
- bending
EN 384 shall not be less
than declared values.
- compressive

Density

Modulus of elasticity in
bending
N
...