ISO 12578:2016

INTERNATIONAL ISO
STANDARD 12578
Second edition
2016-05-01
Timber structures — Glued laminated
timber — Component performance
requirements
Structures en bois — Bois lamellé-collé — Performance des
composants et exigences
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 3
5 Component requirements . 4
5.1 General . 4
5.2 Timber . 4
5.3 Adhesives . 4
5.4 End joints in laminations . 4
5.4.1 Qualification requirements . 4
5.4.2 Verification of on-going production . 4
5.5 Glue line integrity and strength . . 4
6 Manufacturing requirements . 6
6.1 General . 6
6.2 Adhesives . 6
6.3 Timber . 6
7 Qualification . 6
8 Factory production internal quality control . 6
8.1 General . 6
8.2 End joints . 6
8.3 Glue line integrity . 7
8.4 Gluing record . 7
9 Quality system . 7
Annex A (informative) Personnel, facilities, manufacture and quality control .8
Annex B (informative) Formaldehyde emission .13
Bibliography .14
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
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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
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on the ISO list of patent declarations received (see www.iso.org/patents).
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Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 165, Timber structures.
This second edition cancels and replaces the first edition (ISO 12578:2008), which has been technically
revised.
iv © ISO 2016 – All rights reserved

Introduction
Glued laminated timber is obtained by bonding together a number of laminations having their grain
essentially parallel. In this way, a member with rectangular solid cross-section can be produced. Other
non-rectangular shapes can also be produced.
The purpose of the requirements in this International Standard is to provide minimum performance
requirements to ensure the in-service performance of the glued laminated timber. The requirements
will need to be supplemented to take into consideration special conditions, materials or functional
requirements.
INTERNATIONAL STANDARD ISO 12578:2016(E)
Timber structures — Glued laminated timber —
Component performance requirements
1 Scope
This International Standard specifies requirements for the components of glued laminated timber
members for structural use.
This International Standard is applicable to products with a finished lamination thickness of not more
than 50 mm.
Although most glued laminated timber is made from coniferous species, this International Standard
also applies to broad leaf species if the tests specified in this International Standard show that a
satisfactory glue bond can be achieved.
The basic requirements apply to structural members of all service classes; however, special precautions
are necessary for service class 3, for example, the use of weather resistant adhesives (see 5.3).
This International Standard does not apply to the determination of strength and stiffness characteristics.
Annex B contains informative materials for formaldehyde emission.
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.
ISO 9709, Structural timber — Visual strength grading — Basic principles
ISO 13912, Structural timber — Machine strength grading — Basic principles
ISO 10983:2014, Timber — Finger joints — Minimum production requirements and testing methods
1)
ISO 8375:— , Timber structures — Glued laminated timber — Test methods for determination of physical
and mechanical properties
ISO 12579, Timber structures — Glued laminated timber — Method of test for shear strength of glue lines
ISO 12580, Timber structures — Glued laminated timber — Methods of test for glue-line delamination
ISO 20152-1, Timber structures — Bond performance of adhesives — Part 1: Basic requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12579, ISO 12580, ISO 20152-1
and the following apply.
3.1
glued laminated timber
glulam
structural member formed by bonding together timber laminations (3.7) with their grain running
essentially parallel to the member’s longitudinal axis
1) To be published. (Revision of ISO 8375:2009)
3.2
horizontal glulam
glued laminated timber (3.1) with the wide faces of the laminations (3.7) perpendicular to the direction
of the larger cross-sectional dimension
Note 1 to entry: See Figure 1.
Note 2 to entry: This International Standard does not cover vertical glulam.
3.3
service class
group designation characterized by the moisture content of the members corresponding to the
temperature and relative humidity of the surrounding air
3.3.1
service class 1
group designation characterized by a moisture content in the materials corresponding to a temperature
of 20 °C and the relative humidity of the surrounding air exceeding 65 % for a few weeks per year
Note 1 to entry: In service class 1, the average equilibrium moisture content of most softwoods does not
exceed 12 %.
[SOURCE: ISO 20152-1:2010, 3.1]
3.3.2
service class 2
group designation characterized by a moisture content in the materials corresponding to a temperature
of 20 °C and the relative humidity of the surrounding air exceeding 85 % for a few weeks per year
Note 1 to entry: In service class 2, the average equilibrium moisture content of most softwoods does not exceed
20 %. Such conditions include resistance to the effects of moisture on structural performance due to construction
delays or other conditions of similar severity.
[SOURCE: ISO 20152-1:2010, 3.2]
3.3.3
service class 3
group designation characterized by climatic conditions leading to moisture contents higher than
service class 2 (3.3.2), such as when a member is fully exposed to the weather
[SOURCE: ISO 20152-1:2010, 3.3]
3.4
maximum delamination percentage
maximum delamination length of one glue line in the test piece, measured on both end-grain surfaces
of the test specimen multiplied by 100 and divided by the total length of glue lines on the two end-grain
surfaces of each test piece for a single glue line in a test piece
Note 1 to entry: As defined in ISO 12580:2007, 8.3.
3.5
total delamination percentage
delamination length of all glue lines on the two end-grain surfaces in the test piece multiplied by 100
and divided by two times the length of one glue line
Note 1 to entry: As defined in ISO 12580:2007, 8.2.
3.6
wood failure percentage
percentage of the wood failure area in relation to the total sheared area
[SOURCE: ISO 12579:2007, 3.5]
2 © ISO 2016 – All rights reserved

3.7
lamination
piece or pieces of timber of not more than 50 mm in thickness, with or without end joints forming part
of a glulam member
Figure 1 — Glue lines in cross-sections showing the normal position of the glue lines
3.8
declared strengths
mean strength, f , and characteristic strength, f , of end joints strengths
x,dc x,dc,k
chosen by the manufacturer and used as a basis for determining compliance with the end joint strength
requirements of this International Standard
Note 1 to entry: All values can be either bending (m) or tension (t) strength depending on which method of
compliance testing is chosen.
Note 2 to entry: For established production facilities, the declared strengths may be determined using historical
data and appropriate statistical methods.
3.9
qualification
process of assessing, through physical testing and statistical processing of test data, if the output from
a combination of tools, materials and people engaged in producing glued laminated timber products
meets the requirements of this International Standard
4 Symbols
mean end joint strength determined by qualification testing and statistical processing (mPa)
f
x
characteristic end joint strength determined by qualification tests and statistical process-
f
x,k
ing (mPa)
required mean strength of the end joints (mPa)
f
x,dc
shear strength (mPa)
f
v
x subscript indicating bending (m) or tension (t)
dc declared properties
5 Component requirements
5.1 General
The grading of the timber shall result in reliable strength and stiffness properties in the laminations.
The bonding operations shall result in reliable and durable bonds in end joints and between laminations.
5.2 Timber
The timber shall be graded in conformity with either ISO 9709 or ISO 13912. The strength and stiffness
properties of the glued laminated timber shall be established in accordance with ISO 8375.
5.3 Adhesives
The adhesive shall enable joints of such strength and durability to be produced such that the integrity
of the bond is maintained throughout the intended lifetime of the structure.
The adhesive shall be chosen considering the conditions during construction and in service including
climate, moisture conditions, exposure to elevated temperature, the timber species, the preservative
used (if any) and the production methods.
Adhesives shall meet the requirements of ISO 20152-1.
NOTE Additional requirements for adhesives may be specified by national standards or governing codes.
5.4 End joints in laminations
5.4.1 Qualification requirements
Mean declared strength, f , and characteristic declared strength, f , of end joints shall be
x,dc x,dc,k
selected by the manufacturer after qualification testing using one of the methods described in
ISO 10983:2014, 6.5. Alternatively, the values may be obtained from historical records where these are
available. Declared values of this strength shall satisfy the following:
— mean declared strength, ff£ ;
x,dc x,k
— characteristic declared strength, ff£ .
x,dc,k x,k
5.4.2 Verification of on-going production
End joints shall comply with the requirements of ISO 10983:2014, 6.6. In interpreting ISO 10983:2014,
6.6, the declared values may be used in lieu of the corresponding f and f values.
x x,k
5.5 Glue line integrity and strength
5.5.1 The glue line integrity shall be based on testing of the glue line in a full cross-sectional specimen,
cut from the manufactured glulam member.
The spe
...