Timber structures - Testing of joints made with mechanical fasteners - Requirements for timber density (ISO 8970:2020)

This document specifies a method based on density, for the selection of pieces of wood used in
determining the strength and stiffness properties of joints between members of structural timber
made with mechanical fasteners. It is intended to be used in conjunction with a test standard specifying
a test method.
It is assumed that the wood pieces are conditioned to the relevant conditions, that the wood density is
normally distributed and that any deviations are reported.
This document is applicable only to specimens of structural timber.
NOTE It is emphasized that the wood density is only one of the properties that can influence the strength of
a joint. Other relevant properties are, for example, growth-ring size and orientation, toughness and hardness.

Holzbauwerke - Prüfung von mechanischen Verbindungen - Anforderungen an die Rohdichte des Holzes (ISO 8970:2020)

Dieses Dokument legt ein Verfahren fest, bei dem Holzstücke zur Bestimmung der Festigkeits  und Steifigkeitseigenschaften von Verbindungen zwischen Holzelementen für tragende Zwecke mit mecha-nischen Verbindungsmitteln auf der Grundlage der Rohdichte ausgewählt werden. Die Anwendung ist zusammen mit einer Prüfnorm, die ein Prüfverfahren festlegt, vorgesehen.
Es wird vorausgesetzt, dass eine Konditionierung der Holzstücke bei den relevanten Bedingungen erfolgt, dass die Holzrohdichte normalverteilt ist und dass alle Abweichungen bekannt sind.
Dieses Dokument bezieht sich nur auf Probekörper aus Holz für tragende Zwecke.
ANMERKUNG Es wird besonders darauf hingewiesen, dass die Holzrohdichte nur eine der Eigenschaften ist, die die Tragfähigkeit einer Verbindung beeinflussen können. Andere diesbezügliche Eigenschaften sind z. B. Jahresringbreite und  ausrichtung, Belastbarkeit und Härte.

Structures en bois - Essai sur assemblages réalisés par organes mécaniques - Exigences concernant la masse volumique du bois (ISO 8970:2020)

Le présent document spécifie une méthode de prélèvement, basée sur la masse volumique, des pièces de bois utilisées pour déterminer les propriétés de résistance et de rigidité des assemblages d'éléments structuraux en bois réalisés par des organes mécaniques. Elle est destinée à être utilisée conjointement avec une norme d'essai spécifiant une méthode d'essai.
Il est supposé que les pièces de bois sont conditionnées conformément aux conditions applicables, que la masse volumique du bois est distribuée selon une loi normale et que tout écart est consigné.
Le présent document s'applique uniquement aux échantillons de bois de structure.
NOTE       Il est souligné que la masse volumique du bois n'est qu'une des propriétés pouvant avoir une incidence sur la résistance d'un assemblage. D'autres propriétés concernées sont, par exemple, la taille et l'orientation des cernes de croissance, et la dureté.

Lesene konstrukcije - Preskušanje zvez s kovinskimi veznimi sredstvi - Zahteve za gostoto lesa (ISO 8970:2020)

General Information

Status
Published
Public Enquiry End Date
19-Nov-2018
Publication Date
16-Jun-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
09-Apr-2020
Due Date
14-Jun-2020
Completion Date
17-Jun-2020

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SLOVENSKI STANDARD
SIST EN ISO 8970:2020
01-julij-2020
Nadomešča:
SIST EN ISO 8970:2010
Lesene konstrukcije - Preskušanje zvez s kovinskimi veznimi sredstvi - Zahteve za
gostoto lesa (ISO 8970:2020)
Timber structures - Testing of joints made with mechanical fasteners - Requirements for
timber density (ISO 8970:2020)
Holzbauwerke - Prüfung von mechanischen Verbindungen - Anforderungen an die
Rohdichte des Holzes (ISO 8970:2020)
Structures en bois - Essai sur assemblages réalisés par organes mécaniques -
Exigences concernant la masse volumique du bois (ISO 8970:2020)
Ta slovenski standard je istoveten z: EN ISO 8970:2020
ICS:
91.080.20 Lesene konstrukcije Timber structures
SIST EN ISO 8970:2020 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 8970:2020

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SIST EN ISO 8970:2020


EN ISO 8970
EUROPEAN STANDARD

NORME EUROPÉENNE

April 2020
EUROPÄISCHE NORM
ICS 91.080.20 Supersedes EN ISO 8970:2010
English Version

Timber structures - Testing of joints made with
mechanical fasteners - Requirements for timber density
(ISO 8970:2020)
Structures en bois - Essai sur assemblages réalisés par Holzbauwerke - Prüfung von mechanischen
organes mécaniques - Exigences concernant la masse Verbindungen - Anforderungen an die Rohdichte des
volumique du bois (ISO 8970:2020) Holzes (ISO 8970:2020)
This European Standard was approved by CEN on 13 March 2020.

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, Turkey 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
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 8970:2020 E
worldwide for CEN national Members.

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SIST EN ISO 8970:2020
EN ISO 8970:2020 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 8970:2020
EN ISO 8970:2020 (E)
European foreword
This document (EN ISO 8970:2020) has been prepared by Technical Committee ISO/TC 165 "Timber
structures" in collaboration with Technical Committee CEN/TC 124 “Timber structures” the secretariat
of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2020, and conflicting national standards shall
be withdrawn at the latest by October 2020.
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 ISO 8970:2010.
According to the CEN-CENELEC Internal Regulations, the national standards organizations 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, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 8970:2020 has been approved by CEN as EN ISO 8970:2020 without any modification.

3

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SIST EN ISO 8970:2020

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SIST EN ISO 8970:2020
INTERNATIONAL ISO
STANDARD 8970
Third edition
2020-03
Timber structures — Testing of joints
made with mechanical fasteners —
Requirements for timber density
Structures en bois — Essai sur assemblages réalisés par organes
mécaniques — Exigences concernant la masse volumique du bois
Reference number
ISO 8970:2020(E)
©
ISO 2020

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SIST EN ISO 8970:2020
ISO 8970:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

---------------------- Page: 8 ----------------------
SIST EN ISO 8970:2020
ISO 8970:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 1
5 Wood sampling method and requirements . 1
5.1 General . 1
5.2 Sampling method and requirements . 2
6 Test report . 2
Annex A (normative) Corrections to target conditions . 4
Annex B (informative) Background information . 6
Bibliography . 9
© ISO 2020 – All rights reserved iii

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SIST EN ISO 8970:2020
ISO 8970:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 165, Timber structures, in collaboration
with the European Committee for Standardization (CEN) Technical Committee CEN/TC 124, Timber
structures, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna
Agreement).
This third edition cancels and replaces the second edition (ISO 8970:2010), which has been technically
revised.
The main changes compared to the previous edition are as follows:
In this edition the sampling method aims not only at ensuring that the selected pieces have a mean
[1]
density comparable to the wood to which the test result is intended to be applied , but also requiring
the coefficient of variation of the density to be reflected. Only then the characteristic value of the
[2]
strength determined by the test can be used directly .
If it is not possible to obtain wood with the target mean value and variation of the wood density, the
normative Annex A provides a correction method. The informative Annex B provides background to the
correction procedure.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

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SIST EN ISO 8970:2020
ISO 8970:2020(E)

Introduction
The sampling method given aims at ensuring that the selected pieces have a density distribution
comparable to the timber to which the test result is intended to be applied. When this is fulfilled, the
results can be used directly to determine the characteristic value of the strength parameter.
As it is often difficult to obtain a variation of the density similar to that allowed in a strength class, a
correction method is given to obtain a corrected coefficient of variation for the strength parameter.
It should be kept in mind that the effect of density on the load-bearing capacity of connections is in
many cases less significant than expected, and that many other parameters influence it.
© ISO 2020 – All rights reserved v

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SIST EN ISO 8970:2020

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SIST EN ISO 8970:2020
INTERNATIONAL STANDARD ISO 8970:2020(E)
Timber structures — Testing of joints made with
mechanical fasteners — Requirements for timber density
1 Scope
This document specifies a method based on density, for the selection of pieces of wood use
...

SLOVENSKI STANDARD
oSIST prEN ISO 8970:2018
01-november-2018
Lesene konstrukcije - Preskušanje zvez s kovinskimi veznimi sredstvi - Zahteve za
gostoto lesa (ISO/DIS 8970:2018)
Timber structures - Testing of joints made with mechanical fasteners - Requirements for
timber density (ISO/DIS 8970:2018)
Holzbauwerke - Prüfung von mechanischen Verbindungen - Anforderungen an die
Rohdichte des Holzes (ISO/DIS 8970:2018)
Structures en bois - Essai des assemblages réalisés par organes mécaniques -
Exigences concernant la masse volumique du bois (ISO/DIS 8970:2018)
Ta slovenski standard je istoveten z: prEN ISO 8970
ICS:
91.080.20 Lesene konstrukcije Timber structures
oSIST prEN ISO 8970:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 8970:2018

---------------------- Page: 2 ----------------------
oSIST prEN ISO 8970:2018
DRAFT INTERNATIONAL STANDARD
ISO/DIS 8970
ISO/TC 165 Secretariat: SCC
Voting begins on: Voting terminates on:
2018-09-12 2018-12-05
Timber structures — Testing of joints made with
mechanical fasteners — Requirements for timber density
Structures en bois — Essai des assemblages réalisés par organes mécaniques — Exigences concernant la
masse volumique du bois
ICS: 91.080.20
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 8970:2018(E)
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. ISO 2018

---------------------- Page: 3 ----------------------
oSIST prEN ISO 8970:2018
ISO/DIS 8970:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

---------------------- Page: 4 ----------------------
oSIST prEN ISO 8970:2018
ISO/DIS 8970:2018(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Symbols and units . 1
4 Timber sampling method and requirements . 1
4.1 General . 1
4.2 Sampling method and requirements . 2
5 Test report . 2
Annex A (Normative) Corrections to target conditions . 3
Annex B (Informative) Background information . 5
Bibliography . 8
© ISO 2018 – All rights reserved iii

---------------------- Page: 5 ----------------------
oSIST prEN ISO 8970:2018
ISO/DIS 8970:2018(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 8970 was prepared by Technical Committee ISO/TC 165, Timber structures.
This third edition cancels and replaces the second edition (ISO 8970:2010), which has been technically
revised.
iv © ISO 2018 – All rights reserved

---------------------- Page: 6 ----------------------
oSIST prEN ISO 8970:2018
ISO/DIS 8970:2018(E)

Introduction
The sampling method given aims at ensuring that the selected pieces have a density distribution
comparable to the timber to which the test result is intended to be applied. When this is fulfilled, the
results can be used directly to determine the characteristic value of the strength parameter.
As it is often difficult to obtain a variation of the density similar to that allowed in a strength class, a
correction method is given to obtain a corrected coefficient of variation for the strength parameter.
It should be kept in mind that the effect of density on the load-bearing capacity of connections is in
many cases less significant than expected, and that many other parameters influence it.
© ISO 2018 – All rights reserved v

---------------------- Page: 7 ----------------------
oSIST prEN ISO 8970:2018

---------------------- Page: 8 ----------------------
oSIST prEN ISO 8970:2018
DRAFT INTERNATIONAL STANDARD ISO/DIS 8970:2018(E)
Timber structures — Testing of joints made with
mechanical fasteners — Requirements for timber density
1 Scope
This International Standard specifies a method based on density, for the selection of pieces of timber
used in determining the strength and stiffness properties of joints between members of structural
timber made with mechanical fasteners. It is intended to be used in conjunction with a test standard
specifying a test method.
It is assumed the timber density is normally distributed and that any deviations are reported.
This International Standard is applicable only to specimens of structural timber.
NOTE It is emphasized that the timber density is only one of the properties that may influence the strength
of a joint. Other relevant properties are, for example, growth-ring size and orientation, toughness and hardness.
2 Normative references
The following referenced documents are indispensable for the application 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.
ISO 13061-2, Physical and mechanical properties of wood — Test methods for small clear wood specimens —
Part 2: Determination of density for physical and mechanical tests
3 Symbols and units
k statistical factor;
V is the coefficient of variation of the density of the timber to which the test results are applied;
ρ,tar
ρ is the density of a timber piece, expressed in kilograms per cubic metre;
ρ is the mean density of the timber to which the test results are applied, expressed in kilograms
m,tar
per cubic metre.
4 Timber sampling method and requirements
4.1 General
The timber shall be at equilibrium at a relative humidity (RH) of (65 ± 5) % and a temperature of
(20 ± 2) °C at the time of testing. It shall be reported whether the timber wad dried or moistened during
the conditioning.
NOTE 1 The moisture content at equilibrium is lower when reached by moistening than if reached by drying,
which may affect the test results. The test standard might specify if the equilibrium condition should be reach
through drying.
The density shall be determined in accordance with ISO 13061-2 part 2 for the actual moisture content
...

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