The Tall Timber Student Housing project at the British Columbia Institute of Technology (BCIT) in Burnaby, British Columbia, is a 12-storey structure comprising of 11 mass timber floors over 1 story of concrete to house 470 single occupancy student resident units. This project represents the first of the next generation of point-supported CLT structures and marks significant advancement in tall, hybrid, mass timber construction.

Each mass timber level comprises of flat, two-way spanning, HemFir cross-laminated timber (CLT) floor plates, point-supported on steel columns without beams, and uses 3.5-meter wide CLT panels. The CLT panels consist of 5 total layers of 2x lumber, interlaced to provide adequate bending resistance and stiffness in two directions with consideration for punching shear at highly loaded column locations.

The architectural layout lends to the CLT panel layout: the width of a unit aligns with the width of the CLT panel. The depth of the building was also set to be within a reasonable shipping length of CLT panel. Column grid spacing was then maximized over this depth, minimizing then the number of column grids and their impact to the interior layout.

The steel HSS columns for support of the CLT floor fit within a standard party wall assembly, yielding a higher net-to-gross floor space ratio, key to maximizing occupiable space and layout efficiency. The columns are then encapsulated for fire within the walls. The column-to-column connection was then designed for simplicity, accuracy, and to add speed to steel erection, comprising of a flat bearing plate over the column to support the CLT panels, a tuning fork vertical plate detail receive the column above and within the same tight tolerances as the mass timber, and 4- thru bolts to lock in the CLT panels and provide a nominal panel-to-panel connection.

Construction began fall 2022, with the completion of the concrete podium in January 2024. The use of prefabricated components, such as wide-format CLT panels and steel braced frames, played a pivotal role in speeding up the construction process. The braced frames were prefabricated in 5- and 6-story lifts, in self-stabilizing configurations at egress cores, allowing for the lateral resisting core construction to be completed before the first CLT floor was installed.

By February 2024, the mass timber floors were being installed with the subsequent install of the large format, prefabricated cladding systems starting two floors below, ensuring that the tower was enclosed quickly to limit exposure of the wood. The project topped out in July 2024 and was fully enclosed by September 2024.

The construction schedule was planned to optimize efficiency:

• CLT Installation Cycle: Starting on Level 3, CLT was installed on a 2-week cycle. Week 1 involved the laydown of the entire floor plate, while Week 2 focused on installing the steel HSS columns for the next floor’s support.
  
• Façade Enclosure: By the beginning of Week 2 for the CLT installation for Level 4, two floors below, a floor was already being enclosed with the façade.
  
• Drywall Encapsulation: Starting in Week 2 of the CLT installation for Level 6, four floors below, a floor was being encapsulated with drywall. This efficient schedule repeated for each floor up from this level.

The results of this project are already influencing design and construction of future mass timber buildings, paving the way for more sustainable and efficient construction practices.

Point-supported CLT testing validated the design approach, and the cost savings realized by utilizing prefabrication for CLT panels and steel braced frames, along with the cladding systems, demonstrates point-supported CLT systems are a cost-competitive alternative to traditional concrete structures.