The Humber College Cultural Hub is a 375,000 ft² hybrid facility housing Humber’s School of Creative Arts. This summer, construction continues as a five-story mass timber student residence is being built above a concrete podium and parts of the original student centre building, with a structural steel transfer truss system in place.
Entuitive is the structural engineer of record on the project and is responsible for the design and contract administration of the entire structure, which includes timber-to-timber connections.
Associate Sean Lou-Hing recently shared his insights on the project, including the benefits of mass timber as a building material.
What are the current codes & regulations for timber as a building material? Sean, the Humber College Cultural Hub represents Entuitive's largest timber design to date. At what point in the process was mass timber selected, and what are its main advantages?
In the last 50+ years, the market has been dominated by reinforced concrete and structural steel buildings. Still today, the vast majority of buildings are in concrete or steel.
Mass timber is often integrated into project design where exposed timber is important to the building’s aesthetic. From a structural perspective, it is gaining in popularity, but it is still somewhat rare by comparison.
The material is lightweight, which makes transportation and on-site handling much easier. Timber also typically arrives prefabricated and can be erected on site. This is similar to precast concrete components but easier to manipulate, lift, and position. Also, it’s a natural, renewable, and sustainable material with a light carbon footprint. Studies even show a positive impact on occupant health and wellness when working and living within a timber-exposed building.
During the evaluation process, we studied various framing schemes and materials during the planning phases, including cast-in-place concrete, structural steel, and mass timber, alongside construction cost, schedule, embodied carbon, and construction safety. In the end, mass timber was evaluated as the right material for the structure based on the team’s defined criteria.
Humber’s student residence is made up of glulam columns and beams, cross-laminated timber (CLT) floor and roof panels and CLT shear walls. The lighter weight of the material results in lighter foundations and reduced demand on the building’s lateral system.
Mass timber was a key priority in this upper part of the structure, the student residence, to keep the loads light.
We’re using an Integrated Project Delivery approach on this project. What are some advantages and considerations of this approach?
The Integrated Project Delivery (IPD) approach was ultimately a client decision. It was led by Humber’s desire for a more collaborative design process as opposed to the ‘traditional’ procurement model. The collaborative formation set the groundwork for structured interaction between the architect, engineers, general contractor, and trade partners, including the mass timber fabricators.
Due to shifts in the project timeline based on COVID restrictions and access to materials, and in the context of the school year and ideal building season, the IPD approach required all parties’ timelines and deliverables to be fully communicated at the outset and updated, when necessary, together.
The IPD approach also enabled Entuitive to lead the exploration of necessary design opportunities to address eventual budget limitations brought on by material cost inflation.
The original building is home to a historic recording studio, which had to remain operational during construction. What was Entuitive’s solution to protecting the space while effectively building above it?
It certainly required careful sequencing with Humber College to remain accessible and operational in the middle of a construction site. The land next to and overtop the studio was underutilized and identified as a key development space. Building around the studio was relatively simple. Building over top, however, needed some creativity.
A collaborative effort between Entuitive, the steel supplier, and general contractor partners determined structural steel as the most efficient approach. We developed a storey-high transfer truss scheme. It involved the right choice of materials, focused on reducing steel weight. Lighter structural elements, lifted with smaller cranes, reduced construction and material costs.
The technical solution was to use heavy 5-meter-deep steel transfer trusses, fabricated off-site, and to lift them into place over a short downtime period, off hours.
There are two structural programs for the academic and residence floors. What challenges did this present and how did Entuitive solve them?
Two program distinctions are associated with this project since the student residence floor sits atop the academic levels. The structure for the academic floors, levels one to three, required longer spans in the range of eight to eleven meters. These longer spans are required to accommodate large classrooms and provide increased flexibility for future interior changes. The floors were typically made up of concrete slabs and drop panels at column locations. Stacking these two distinct programs is one structural challenge we had to resolve since it resulted in multiple column transfers. A multitude of transfer schemes were introduced, including 2.5-meter-deep reinforced concrete transfer beams over the top of the performing arts hall and a 4.5-meter-deep steel transfer truss over top of the existing recording studio. Once again, we benefitted from the use of mass timber for the residence floors, as it reduced the weight of the structure and loads imposed on the transfer elements. This choice reduced the transfer beam weight by 35%, the steel transfer truss weight by 35%, and the foundation weight by 20%.
Thanks for chatting with us, Sean. If you’d like to learn more about Mass Timber design, connect with Sean Lou-Hing here.
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