EN 14374:2004

Timber structures - Structural laminated veneer lumber - Requirements

This document specifies the requirements for laminated veneer lumber for structural applications. The tests to be used, methods to carry out the evaluation of conformity and content of the marking of the product are given.
This document does not cover laminated veneer lumber treated against biological attack or fire.

Holzbauwerke - Furnierschichtholz für tragende Zwecke - Anforderungen

Diese Europäische Norm legt die Anforderungen an Furnierschichtholz für tragende Zwecke fest. Die anzuwendenden Prüfverfahren, die Verfahren zur Bewertung der Konformität sowie die Kennzeichnung des Produktes sind angegeben.
Furnierschichtholz, das zum Schutz gegen biologischen Befall oder Feuer behandelt wurde, ist nicht Gegenstand dieser Europäischen Norm.

Structures en bois - LVL (Lamibois) - Exigences

Le présent document spécifie les exigences relatives au lamibois pour application en structure. Les essais à effectuer, les méthodes à utiliser pour évaluer la conformité et le contenu du marquage à appliquer sur le produit sont indiqués.
La présente Norme européenne ne traite pas du lamibois traité contre les attaques biologiques ou le feu.

Lesene konstrukcije – Furnirni slojnat les (LVL) za konstrukcije – Zahteve

General Information

• Status: Published
• Publication Date: 23-Nov-2004
• Withdrawal Date: 30-Aug-2006
• ICS: 79.080 - Semi-manufactures of timber
• ICS: 91.080.20 - Timber structures
• Technical Committee: CEN/TC 124 - Timber structures
• Drafting Committee: CEN/TC 124/WG 3 - Glued laminated timber
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 24-Nov-2004
• Completion Date: 24-Nov-2004
• Directive: 305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Directive: 89/106/EEC - Construction products
• Mandate: M/112 - Mandate to CEN/CENELEC concerning the execution of standardization work for harmonized standards on structural timber products
• Ref Project: SIST EN 14374:2005 - Timber structures - Structural laminated veneer lumber - Requirements

Relations

• Revised: FprEN 14374 - Timber structures - Laminated veneer lumber (LVL) - Requirements
• Effective Date: 18-Jan-2023

Overview

EN 14374:2004 - Timber structures - Structural laminated veneer lumber (LVL) - Requirements is a CEN standard that defines the requirements, test methods, conformity evaluation and marking for LVL used in structural applications. The standard applies to structural laminated veneer lumber (LVL) products and specifies mechanical and physical property requirements, dimensional tolerances, bonding quality and product information. It does not cover LVL that has been treated for biological attack or for fire resistance.

Key topics and technical requirements

• Veneer construction
  • Minimum number of veneers in the cross section: 5
  • Maximum veneer thickness: 6 mm
• Bonding quality
  • Determined per the standard; each glueline must show at least 70% apparent cohesive wood failure
• Dimensions and tolerances
  • Thickness and width tolerances are specified (thickness tolerance expressed as a function of target thickness; width and length tolerances provided)
  • Cross‑section angle tolerance: max deviation about 1:50 (≈1.1°)
• Strength and stiffness
  • Manufacturers must declare characteristic (5th percentile) strength values and mean and characteristic stiffness values (modulus of elasticity and shear modulus)
  • Test methods referenced: EN 408 (bending, tension, compression, local MOE), EN 789 (planar shear)
  • Size-effect corrections and specimen minimum dimensions are specified for certain tests
• Physical properties
  • Density (EN 323) and moisture content (EN 322) determination methods required
• Reaction to fire and formaldehyde
  • Reaction to fire classification per EN 13501-1 when required
  • Release of formaldehyde class must be declared (test methods referenced in annexes / EN 717 / ENV 717 series)
• Evaluation of conformity and marking
  • Procedures for initial type testing, factory production control and product marking are included - the standard supports CE/attestation processes (see informative annexes)

Applications and who uses it

EN 14374 is directly relevant to:

• LVL manufacturers (product specification, production control, marking)
• Testing laboratories and quality control teams (test methods and sampling)
• Structural engineers, specifiers and architects who select LVL for beams, joists, headers and other structural members
• Certifiers and regulatory authorities responsible for conformity assessment and CE marking
• Contractors and procurement professionals verifying product compliance

Using EN 14374 helps ensure LVL used in buildings meets harmonized European requirements for mechanical performance, durability indicators (untreated), and product information.

Related standards

Key referenced standards include EN 408, EN 789, EN 323, EN 322, EN 314-1, EN 13501-1, EN 717-1/2, EN 350-2 and the draft prEN 14358 for statistical evaluation of characteristic values. These form the test and assessment framework for structural LVL under EN 14374.

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Timber structures - Structural laminated veneer lumber - RequirementsLesene konstrukcije – Furnirni slojnat les (LVL) za konstrukcije – ZahteveStructures en bois - LVL (Lamibois) - ExigencesHolzbauwerke - Furnierschichtholz für tragende Zwecke - AnforderungenTa slovenski standard je istoveten z:EN 14374:2004SIST EN 14374:2005en91.080.2079.080ICS:SLOVENSKI
STANDARDSIST EN 14374:200501-maj-2005

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14374November 2004ICS 91.080.20; 79.080English versionTimber structures - Structural laminated veneer lumber -RequirementsStructures en bois - LVL (Lamibois) - ExigencesHolzbauwerke - Furnierschichtholz für tragende Zwecke -AnforderungenThis European Standard was approved by CEN on 22 July 2004.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2004 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14374:2004: E

(EN 14374:2004) has been prepared by Technical Committee CEN/TC 124 "Timber Structures", the secretariat of which is held by SFS. 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 May 2005, and conflicting national standards shall be withdrawn at the latest by May 2005. No existing European Standards are superseded. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). For relationship with EU Directive(s), see informative annex ZA, which is an integral part of this document. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

1 Scope This document specifies the requirements for laminated veneer lumber for structural applications. The tests to be used, methods to carry out the evaluation of conformity and content of the marking of the product are given. This document does not cover laminated veneer lumber treated against biological attack or fire. 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.
EN 314-1, Plywood – Bonding quality – Part 1: Test methods. EN 322, Wood-based panels – Determination of moisture content. EN 323, Wood-based panels – Determination of density. EN 350-2, Durability of wood and wood-based products – Natural durability of solid wood – Part 2: Guide to natural durability and treatability of selected wood species of importance in Europe. EN 408, Timber structures – Structural timber and glued laminated timber – Determination of some physical and mechanical properties. ENV 717-1, Wood-based panels – Determination of formaldehyde release – Part 1: Formaldehyde emission by the chamber method. EN 717-2, Wood-based panels – Determination of formaldehyde release – Part 2: Formaldehyde release by the gas analysis method. EN 789, Timber structures – Test methods – Determination of mechanical properties of wood based panels. EN 1438:1998, Symbols for timber and wood-based products. EN 13501-1, Fire classification of construction products and building elements – Part 1: Classification using test data from reaction to fire tests. prEN 14358, Structural timber – Calculation of characteristic 5-percentile value.

(10 ± 2) %
a)b)tbtb Figure 1 – Thickness t and width b of cross section of laminated veneer lumber. Case a) is the cross section related to edgewise bending while case b) is the cross section related to flatwise bending 4 Requirements 4.1 Veneers The minimum number of veneers in the cross section shall be five. The maximum thickness of each veneer shall be 6 mm. 4.2 Bonding quality The bonding quality shall be determined in accordance with the method given in annex B. For each tested glueline the apparent cohesive wood failure percentage shall be at least 70 %.

α Figure 2 – Example of an angle αααα of a cross section of laminated veneer lumber 4.4 Strength 4.4.1 General The manufacturer of laminated veneer lumber shall declare fifth percentile characteristic strength values. NOTE The orientation of strength is given in annex A. The characteristic values shall be determined from tests given in 4.4.2 to 4.4.9 and evaluated in accordance with the method given in prEN 14358. 4.4.2 Bending strength edgewise The bending strength tests shall be carried out in accordance with the test method given in EN 408. In edgewise bending the width of the specimen shall be at least 100 mm. If the width of the specimen is lower than the reference width of 300 mm, the individual test results shall be multiplied by the factor km,corr: scorrmbk=300, where b is the width of the tested specimen in mm and s is the size effect parameter given by: 05,02−=vs where v is the coefficient of variation of the test results. v may be taken less than 0,10 only if it is verified from at least two years of documented experience. 4.4.3 Bending strength flatwise The bending strength tests shall be carried out in accordance with the test method given in EN 408. In flatwise bending the thickness of the specimen shall be at least 38 mm.
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