ISO 18776:2008

Laminated veneer lumber (LVL) - Specifications

ISO 18776:2008 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. ISO 18776:2008 specifies requirements for the quality of veneers, bond durability, tolerances on dimensions, and structural characterization.

Lamibois (LVL) — Spécifications

General Information

• Status: Published
• Publication Date: 27-Jan-2008
• ICS: 79.060.99 - Other wood-based panels
• Technical Committee: ISO/TC 89/SC 3 - Plywood
• Drafting Committee: ISO/TC 89/SC 3 - Plywood
• Current Stage: 9060 - Close of review
• Completion Date: 04-Jun-2029

Relations

• Amended By: ISO 18776:2008/Amd 1:2013 - Laminated veneer lumber (LVL) - Specifications - Amendment 1
• Effective Date: 13-Oct-2020

Overview

ISO 18776:2008 - Laminated veneer lumber (LVL) - Specifications defines minimum requirements for LVL products intended for general-purpose and structural use in dry, tropical-dry/humid, and high-humidity/exterior conditions. The standard covers material selection, manufacturing controls, bond durability, dimensional tolerances, structural characterization and marking of LVL. It is the reference for suppliers, specifiers and testing laboratories involved in LVL production and certification.

Key topics and technical requirements

• Scope and use classes: Applies to LVL assemblies where veneer grain in outer and most veneers is longitudinal; suitable for internal and protected external structural applications depending on service humidity.
• Quality system / conformance: Requires a formalized manufacturing specification and quality system with in-plant controls and external auditing (consistent with ISO/IEC Guide 65).
• Veneer requirements:
  • Species: any wood species permitted.
  • Thickness: nominal maximum veneer thickness 6.0 mm unless otherwise specified.
  • Quality grading, jointing (edge and end joints) and veneer position (for structural LVL) must be defined.
• Adhesives & bond durability: Adhesive systems must deliver required bond strength and durability; bonding quality is established per ISO 12466 series (chisel test and requirements).
• Dimensional & shape tolerances: Dimensions measured at 10 ±4 % moisture content. Examples of shape limits include spring/bow ≤ 1 mm per 1 000 mm and cupping ≤ 1 mm per 100 mm; squareness ≤ 1 mm in 50 mm; twist calculated by the formula in the standard.
• Mechanical & physical properties: Bending strength and modulus of elasticity (MOE) per ISO 16978; density and moisture content per ISO 9427 and ISO 16979. Structural LVL requires formal structural testing and evaluation to produce characteristic design values.
• Supplementary items: Preservative/chemical treatment guidance, formaldehyde emission measurement (ISO 12460 series), marking and product identification.

Applications

ISO 18776:2008 is used when specifying or producing LVL for:

• Load-bearing members (beams, rafters, studs, joists) where predictable structural properties are required
• Interior structural elements and protected external applications (cladding backer, roof members)
• Situations requiring documented quality control, bond durability and dimensional precision

Who should use this standard

• LVL manufacturers and process engineers
• Structural and civil engineers specifying timber products
• Architects and product specifiers
• Certification bodies, testing laboratories and QA auditors

Related standards (normative references)

Key referenced documents include:

• ISO 12466-1 / ISO 12466-2 (bonding quality)
• ISO 16978 (bending strength and MOE)
• ISO 16979 (moisture content)
• ISO 27567 (measurement of dimensions and shape)
• ISO 12460 series (formaldehyde release)

Keywords: ISO 18776:2008, Laminated veneer lumber, LVL specifications, bond durability, veneer quality, structural LVL, dimensions and tolerances, formaldehyde release, LVL manufacturing.

Standards Content (Sample)

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

Reference number
©
ISO 2008
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2008
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
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
...