Chapter 07 · Materials & footprintsCircular Economy & Materials
Cross-laminated timber (CLT)
Definition
Cross-laminated timber is an engineered wood panel made by gluing layers of sawn lumber together with each layer oriented perpendicular to the adjacent ones, producing strong, dimensionally stable panels for walls, floors and roofs. CLT is roughly five times lighter than concrete by volume and behaves predictably in fire by forming a char layer; as a mass-timber product it stores biogenic carbon, enabling mid- and high-rise timber buildings of up to 18 storeys in some codes.
References
construction, weight and fire behaviour
carbon storage and building heights
Overview
What it means
A structural material that turns buildings from carbon sources into carbon stores, while cutting construction weight, time and waste.
How it is used
CLT features in green-building certifications, embodied-carbon strategies and public-procurement policies favouring timber; supply depends on certified sustainable forestry.
Why it matters
Substituting mass timber for concrete and steel is one of the most concrete (and contested) pathways for cutting the built environment's embodied emissions.