Tallest Mass Timber Tower to Rise in Toronto

Unix Housing Group has filed plans to build a 31-story apartment building at 191-199 College Street in Toronto that will become the tallest mass-timber structure in North America when it is completed.

The mass-timber building, designed by Icon Architects, will feature a unit façade cladding of Building Integrated Photovoltaic (BIPV) pallets, a high-strength reflective lightweight cladding that is infused with a layer of solar cells.

Four three-story “house form” semi-detached Edwardian style buildings will be preserved and incorporated into the design to maintain the high-rise project’s “pedestrian scale,” according to the architects.

About 80 percent of the apartments will be designated as affordable units.

According to a report in archdaily, Icon is working with the Canadian Wood Council on a work-around for the Ontario building code requirement that previously limited mass timber buildings to 12 floors.

The architects plan to utilize amendments adopted by the Council on Tall Buildings and Urban Habitat that have designated wooden building with cross laminated timber (CLT) anchored to concrete cores as “wood-concrete” hybrids.

According to Icon, the use of CLT to build the Toronto tower will reduce the structure’s carbon footprint by more than 3,300 metric tons of greenhouse gas emissions.

An Oakland-based developer who already has under construction a 19-story, 236-unit residential tower in Oakland what will become the tallest mass timber building on the West Coast when completed decided in August to double the size of the project.

Oakland-based developer oWow is planning to build a second 19-story mass timber tower, this one with 269 units, on a half-acre lot at 1523 Harrison Street that oWow purchases for $9.3M in March.

The company said the second tower will have the same design as the building under construction at 1510 Webster Street: 18 stories of mass timber atop a single story of concrete. The buildings will each have a cutout halfway up for a landscaped patio deck, and each will have about 15K of retail and office space.

Last summer, California updated its building code to allow mass timber buildings to reach 18 stories, after the International Building Code approved high-rise mass timber structures after conducting a series of fire safety tests.

The Golden State also increased the square footage allowed on mass timber buildings and issued guidelines for architects. Prior to the change, mass timber buildings had been capped at six stories for residential buildings due to safety concerns.

oWow, which already had a project underway at the Harrison Street site when the building code update was issued last summer, immediately revised its plans to convert the design to a mass timber high rise.

Mass timber is gaining favor as developers seek to reduce the carbon footprint of their buildings by reducing the amount of concrete, which generates significant emissions when it is made. As a construction material, pre-fabricated mass timber components can be assembled much faster than concrete and steel structures.

oWow is aiming to put up the mass timber high-rise apartment buildings at a pace of two floors a week. The developer previously built a five-story mass timber building at 316 12^th Street in Oakland at a rate of one story per week.

The Harrison and Webster mass timber towers will both feature one- and two-bedroom apartments from 400K SF to 700K SF. The developer says the units will be “affordable by design,” with floor plans that reduce foyers and hallways.

The tallest mass timber building in the world right now is the Ascent MKE Building, a 25-story structure that opened in Milwaukee this year. The US Department of Agriculture’s Forest Service supported the project with a wood products innovation grant for design and engineering.

The Forest Service’s products lab conducted critical fire testing of glued-laminated timber columns, also known as Glulam, a manufactured construction product composed of layers of lumber glued together.

According to the Forest Service the three-hour burn test proved that oversized, yet unprotected, glulam columns do not lose structural integrity because outer layer charring protects internal layers of the wooden building components.