Japanese Mass Timber Building to Utilizes SPF Dimension Lumber in its Construction
In a positive move for our industry, Taisei Corporation, one of the five so called “super general contractors” in Japan, recently announced on August 8th that is has developed its “T-WOOD® Truss Floor” unit to achieve large-spans in mass timber buildings using readily available commercial lumber – combining the best of both light frame construction and solid mass timber construction technology into a hybrid structural wood product. To achieve this, a unique and innovative floor product assembly was tested and developed using parallel chord metal nail plate connected (See Photo 2) trusses fabricated with dimensional lumber, sandwiched between and fastened by screws to cross-laminated timber (CLT) panels (See Photo 1) that act as the top and bottom flanges for the floor assembly – essentially creating a large hybrid mass timber beam. These large wooden hybrid beams are prefabricated offsite into sections that are typically 2.4 m wide and 1 m in height which achieve large free spans of up to 14 m for each unit (See Figure 1). The newly developed product is scheduled to be applied to the floor assembly on the 4th floor at Taisei Construction Group’s “Future Technology Field for TAISEI Group / Satte (T-Field / Satte)” (Satte City, Saitama Prefecture), which is currently under construction (See Figure 2) and slated to open in 2026.
Key features of T-WOOD® Truss Floor
- Standard Lumber Use: Built with readily available dimension lumber—no need for custom or engineered wood—making sourcing and design more flexible and cost-effective.
- Hybrid Truss Design: Combines parallel chord trusses with CLT panels as top and bottom flanges, forming a strong, lightweight wooden floor structure.
- Efficient Construction: Reduces both weight and component count compared to traditional methods.
- Utility-Friendly: Open parallel chord truss design allows easy routing of pipes and wiring.
- Long Span Capability: Units can reach up to 14 m with specialized reinforcement hardware.
Application
Taisei Corporation aims to expand the use of wood in architecture by promoting its innovative “T-WOOD®” products. These solutions support carbon storage and enable flexible design for large, column-free spaces in offices, schools, and research facilities—helping advance sustainable building practices in Japan.
