ISO 18776:2008

INTERNATIONAL ISO
STANDARD 18776
First edition
2008-02-01
Laminated veneer lumber (LVL) —
Specifications
Lamibois (LVL) — Spécifications

Reference number
©
ISO 2008
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ii © ISO 2008 – All rights reserved

Contents Page
Foreword. iv
1 Scope . 1
2 Conformance. 1
2.1 Quality system requirements . 1
2.2 Manufacturing specifications . 1
3 Normative references . 2
4 Terms and definitions. 2
5 Materials . 3
5.1 Veneer . 3
5.1.1 General. 3
5.1.2 Species . 3
5.1.3 Thickness . 3
5.1.4 Quality. 3
5.1.5 Jointing . 4
5.2 Adhesives . 4
6 Bonding quality. 4
7 Lay-up (arrangement of veneers). 4
8 Dimensions, shape and tolerances. 4
8.1 Dimensions. 4
8.2 Shape . 5
8.3 Tolerances . 5
8.3.1 Dimensions. 5
8.3.2 Shape . 6
9 Determination of properties. 6
9.1 Physical properties. 6
9.2 Mechanical properties. 6
9.2.1 General. 6
9.2.2 Structural applications. 6
9.3 Supplementary properties . 6
10 Preservative and chemical treatments . 7
10.1 Natural or confered biological durability. 7
10.2 Effect of chemical treatments. 7
11 Formaldehyde release. 7
12 Marking (identification) . 7
Annex A (normative) Veneer quality .9
Annex B (normative) Panel construction (Veneer arangement) . 10
Annex C (informative) Properties to be determined depending on end use. 11
Annex D (informative) Supplementary properties . 12
Bibliography . 13

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 18776 was prepared by Technical Committee ISO/TC 89, Wood-based panels, Subcommittee SC 3,
Plywood.
iv © ISO 2008 – All rights reserved

INTERNATIONAL STANDARD ISO 18776:2008(E)

Laminated veneer lumber (LVL) — Specifications
1 Scope
This International Standard specifies the requirements for Laminated Veneer Lumber (LVL) for general
purposes and structural applications, in dry, tropical-dry/humid or high humidity/exterior conditions. Laminated
Veneer Lumber (LVL) is a general description for an assembly of veneers laminated with an adhesive in which
the grain direction of the outer veneers and most other veneers is in the longitudinal direction.
This International Standard specifies requirements for
⎯ the quality of veneers,
⎯ bond durability,
⎯ tolerances on dimensions, and
⎯ structural characterization.
Characteristic values, to be used for design purposes, are based on testing and evaluation of laminated
veneer lumber.
2 Conformance
2.1 Quality system requirements
Products conforming to this International Standard shall be manufactured to a formalised manufacturing
specification covering all relevant process variables under a quality system which includes
⎯ in-plant process quality control and internal auditing procedures, and
⎯ external auditing of plant process control and end-product quality.
The system shall be consistent with the requirements of ISO/IEC Guide 65.
2.2 Manufacturing specifications
The manufacturing specifications shall set the limits on all variables that affect or correlate with final product
properties, including
a) materials (see Clause 5),
b) bonding quality (see Clause 6),
c) lay-up (construction) (see Clause 7),
d) manufacturing process, and
e) secondary processes and treatment (see, for example, Clause 10).
NOTE The above list is not necessarily exhaustive.
3 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/IEC Guide 65, General requirements for bodies operating product certification systems
ISO 2074, Plywood — Vocabulary
ISO 9427, Wood-based panels — Determination of density
ISO 12460-1, Wood-based panels — Determination of formaldehyde release — Part 1: Formaldehyde
emission by the 1-cubic-metre chamber method
ISO 12460-2, Wood-based panels — Determination of formaldehyde release — Part 2: Small-scale chamber
method
ISO 12460-3, Wood-based panels — Determination of formaldehyde release — Part 3: Gas analysis method
ISO 12460-4, Wood-based panels — Determination of formaldehyde release — Part 4: Dessicator method
ISO 12466-1, Plywood — Bonding quality — Part 1: Test methods
ISO 12466-2, Plywood — Bonding quality — Part 2: Requirements
ISO 16978, Wood-based panels — Determination of modulus of elasticity in bending and of bending strength
ISO 16979, Wood-based panels — Determination of moisture content
ISO 21887, Durability of wood and wood-based products — Use classes
ISO 27567, Laminated veneer lumber — Measurement of dimensions and shape — Method of test
4 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2074 and the following apply.
4.1
laminated veneer lumber
LVL
product made of an assembly of veneers, laminated with an adhesive, in which the grain direction of the outer
veneers and most other veneers are parallel and run in the longitudinal direction
4.2
dry conditions
conditions in which the LVL attains an equilibrium moisture content not exceeding 12 % except for only a few
weeks per year (e.g. ambient temperature of 20 °C and relative humidity of 65 %)
NOTE 1 LVL, suitable for use in these conditions, is considered as suitable for use in biological-use class 1 of
ISO 21887.
NOTE 2 LVL, under these conditions, is appropriate for dry internal applications, excluding any extended direct
exposure to water.
2 © ISO 2008 – All rights reserved

4.3
tropical-dry/humid conditions
conditions in which the LVL attains an equilibrium moisture content not exceeding 18 %, except for only a few
weeks per year (e.g. ambient temperature of 30 °C and relative humidity of 85 %)
NOTE 1 LVL, suitable for use in these conditions, is considered as suitable for use in biological-use class 1 and class 2
of ISO 21887.
NOTE 2 LVL, under these conditions, is appropriate for protected external applications (e.g. behind cladding or under
roof coverings), but is also capable of resisting weather exposure for short periods (e.g. when exposed during the
construction). It is also suitable for interior situations where the service moisture condition is raised above the humidity of
dry conditions.
4.4
high humidity/exterior conditions
conditions leading to higher equilibrium moisture content than in tropical-dry/humid conditions or prolonged
exposure to weather
NOTE LVL, suitable for use in these conditions, is considered as suitable for use in biological-use class 1, 2 and 3 of
ISO 21887.
4.5
structural use
load-bearing application for which predictable and reliable material structural-design properties are required
5 Materials
The following characteristics shall form part of the manufacturing specifications:
5.1 Veneer
5.1.1 General
The following requirements apply at the time of pressing:
The species, species group, mechanical property group or predictor shall be
...