BS EN 16351:2021

This document sets out provisions regarding the performance of characteristics of the following Types of cross laminated timber for use in buildings and bridges: Type 1: Straight or curved cross laminated timber comprising only timber layers but no large finger joints; Type 2: Straight cross laminated timber comprising only timber layers and large finger joints; Type 3: Straight cross laminated timber comprising timber and wood-based panel layers but no large finger joints. This document covers cross laminated timber of all three Types of cross laminated timber: manufactured according to this document, which sets up provisions for: boundary conditions during manufacture of cross laminated timber; moisture content and temperature of timber to be bonded; production of finger joints and bonds between layers; to be used in service class 1 or 2 according to EN1995?1?1 ; made of coniferous species and poplar listed in this document; which may be made of layers made of different species; bonded with phenolic or aminoplastic or moisture curing one-component polyurethane or emulsion polymer isocyanate adhesives of adhesive Type I according to the respective standard; made of timber laminations having a nominal width between 40mm (including) and 300mm (including); built up of at least three orthogonally bonded layers (at least two of them timber layers); which may have, depending on the number of layers, adjacent layers bonded parallel to the grain; made of timber layers which are made of strength graded timber according to EN14081?1 ; made of timber layers having nominal thicknesses between 6mm (including) and 47mm (including); made of timber layers which may comprise edge bonds; having nominal overall thicknesses up to 500mm. Additional provisions of this document apply for straight cross laminated timber comprising only timber layers and comprising large finger joints (Type 2): made from cross laminated timber pieces having the same cross-section and layup; made from cross laminated timber pieces having nominal cross-sectional thicknesses from 51mm (including) up to 345mm (including) and nominal minimum thicknesses of the outer layers not less than 17mm (including); made from cross laminated timber pieces solely comprising timber layers; made from plane cross laminated timber pieces; with parallel x-axes of the jointed components; with large finger joints having a finger length of at least 45mm and fingers which are visible at the two narrow sides of the components; having large finger joints bonded with phenolic or aminoplastic or moisture curing one-component polyurethane adhesives of adhesive Type I according to the respective standard. Additional provisions of this document apply for straight cross laminated timber comprising timber and wood-based panel layers but no large finger joints (Type 3): made of structural wood-based panels specified in this document; made of one panel per layer and; having thicknesses between 6mm (including) and 45mm (including). This document applies to cross laminated timber untreated or treated against biological attack.This document does not cover: cross laminated timber treated with fire retardants; cross laminated timber which is produced from re-used timber or wood-based panels comprising re-used timber. It also lays down procedures for assessment and verification of constancy of performance (AVPC) of cross laminated timber.