ISO/TC 165/WG 2 - Structural glued wood products

This document specifies methods of evaluating the effectiveness of glued laminated timber face and edge bonds within a manufacturing plant by cleaving of the glue line in both dry and wet conditions. It is not intended that it be used for initial type testing where cyclic delamination or block shear is preferred. It is based on the principle that, provided minimum wood failure percentages are met, then the bond strength exceeds the perpendicular to the grain tension strength of the under-lying substrate and therefore the bond is not the weak element limiting the integrity of a glulam assembly.

This document specifies the component performance and manufacturing requirements for prefabricated wood-based I-beams used as structural members in bending applications. It does not cover fire performance, formaldehyde requirements and biological durability. This document gives requirements for manufacturing, in-house quality assurance and periodic re-evaluation of prefabricated wood-based I-beams. Wood-based I-beams tested according to this document are intended for use in covered conditions and utilizing components that are able to resist the effects of moisture on structural performance due to construction delays or other conditions of similar severity, but not permanently exposed to the weather. NOTE The service conditions are similar to "Service class 2" as defined in ISO 20152‑1. Testing, evaluation and performance characterization requirements for prefabricated wood-based I-beams are covered in ISO 22389‑1. This document does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this document to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use.

This document specifies requirements for establishing the characteristic properties of structural laminated veneer lumber (LVL), including 5th percentile strength values, stiffness characteristics and other performance characteristics, related to its end use as a structural product for dry use (service class 1). It is applicable to members used in flatwise or edgewise bending orientations. It does not cover the assessment of formaldehyde requirements, biological durability, fire performance or manufacturing, such as quality control and marking.

This document reviews the methodologies or analytical models that have been used to develop the strength and stiffness of structural glued laminated timber (glulam) from the characteristic properties of lumber laminations. The review is limited to the methodologies used in Europe, the USA, Australia/New Zealand, and Canada as they represent different fundamental philosophies in these areas. As a result, the methodologies are not intended to be combined unless there is clear understanding of the fundamental assumptions adopted by the respective methodologies. NOTE Detailed assumptions used by the respective methodologies are available from the standards listed in the Bibliography.

This document establishes the basic principles for component performance and minimum production requirements for cross laminated timber (CLT). This document also contains scheme requirements for conformance, as provided in Annex D. The document is applicable to CLT products which are manufactured from solid-sawn timber or wood based panels built up of at least three layers in which the grain of adjoining layers are at right angles to each other. This document provides CLT dimension tolerances; component requirements; performance criteria; production, testing and trade marking guidance; and minimum requirements for factory production control. This document is based on known species, species combination and/or wood based panel structural performance and bondability. CLT qualified in accordance with the provisions of this document are intended to resist the effects of moisture on structural performance as can occur due to construction delays or other conditions of similar severity. NOTE This document does not include how CLT is to be used and installed, as it will be detailed in ISO 16696-2.

ISO 8375:2017 specifies test methods suitable for determining the following characteristic values of glued laminated timber: modulus of elasticity in bending; shear modulus; bending strength; modulus of elasticity in tension parallel to the grain; tension strength parallel to the grain; modulus of elasticity in compression parallel to the grain; compression strength parallel to the grain; modulus of elasticity in tension perpendicular to the grain; tension strength perpendicular to the grain; modulus of elasticity in compression perpendicular to the grain; compression strength perpendicular to the grain and shear strength. In addition, the determination of dimensions, moisture content and density are specified. ISO 8375:2017 is applicable to rectangular shapes of glued laminated timber.

ISO 12578:2016 specifies requirements for the components of glued laminated timber members for structural use. ISO 12578:2016 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). ISO 12578:2016 does not apply to the determination of strength and stiffness characteristics. Annex B contains informative materials for formaldehyde emission.

ISO 22389-1:2010 specifies the requirements for prefabricated wood-based I-beams used as structural members in bending applications. It gives procedures for establishing and evaluating structural capacities of prefabricated wood-based I-beams. The capacities considered are shear, moment, stiffness, bearing, and flange tension and compression. Procedures for establishing common details are given and certain end-use considerations specific to wood-based I-beams are itemized.

ISO 22390:2010 specifies requirements for establishing the characteristic properties of structural laminated veneer lumber (LVL), including 5th percentile strength values, stiffness characteristics and other performance characteristics, related to its end use as a structural product for dry use (bonding class 1). It is applicable to members used in flatwise or edgewise bending orientations.

ISO 12578:2008 specifies requirements for the components of glued laminated timber members and minimum requirements for the production of such members for structural use. ISO 12578:2008 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, ISO 12578:2008 also applies to broad-leaf species if the tests specified in ISO 12578:2008 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. ISO 12578:2008 does not apply to the determination of strength and stiffness characteristics.

ISO 19993:2007 specifies methods of evaluating the effectiveness of glued, laminated timber-face and edge bonds within a manufacturing plant by cleaving of the glue line in both dry and wet conditions.