Steel and concrete dominate large buildings but carry heavy carbon footprints. Mass timber — large engineered wood elements — is emerging as a structural alternative. Its flagship product, Cross-Laminated Timber (CLT), is strong and stable enough to build mid- and high-rise structures, with far lower embodied carbon and the bonus of storing sequestered CO₂ in the wood.
Working principle
CLT is made by stacking layers of timber boards with their grain oriented at 90° to each other (cross-laminated) and bonding them under pressure. This crosswise layup gives the panel strength and dimensional stability in both directions — like plywood scaled up to structural size — letting it act as floors, walls and roofs. Panels are prefabricated precisely off-site, then assembled rapidly, reducing construction time and waste.
| Property | Concrete / steel | Mass timber (CLT) |
|---|---|---|
| Embodied carbon | High | Low; stores CO₂ |
| Weight | Heavy | Light (smaller foundations) |
| Construction speed | Slower, wet trades | Fast, prefabricated |
| Considerations | Established codes | Fire, moisture design |
Addressing the mythWood is combustible, but thick mass-timber elements char predictably, forming an insulating layer that protects the core — allowing engineered, code-compliant fire performance.
Applications
- Mid- and high-rise residential and office buildings
- Schools, sports halls and large-span roofs
- Hybrid timber-concrete floors for tall towers
References & further reading
- Brandner et al., “Cross laminated timber (CLT): overview and development,” European J. of Wood Products, 2016.
- Ramage et al., “The wood from the trees: The use of timber in construction,” Renewable & Sustainable Energy Reviews, 2017.
- FPInnovations, “CLT Handbook,” 2013.