The Architect's Newspaper ( View Original )

Progress

At 978 feet, Toronto’s First Canadian Place is the tallest occupied building in Canada. While that claim to fame has endured since its construction in 1975, the tower’s white Carrara marble cladding has not fared so well. The exterior of the building had not undergone any significant changes beyond general maintenance, said Dan Shannon of Moed de Armas & Shannon Architects (MdeAS).

“Over time, the marble had deteriorated to the point that one piece of stone had fallen from the building,” said Shannon. “The anchoring, the stone itself, was in a place where it could no longer be maintained, and a change had to be made.” But with tenants like BMO Harris, Manulife Financial, and other major Canadian corporations, primary building owner Brookfield was left with little time to renovate. MdeAS and B+H Architects, who worked as the architect of record, had to replace 45,000 pieces of marble in one year—a job Shannon said would easily take two years under typical circumstances.

To accomplish the job the team commissioned a custom suspended rig with three tiers for simultaneous work. The rig was climate controlled, but not airtight. “This was an occupied building,” said Shannon. “You can imagine trying to change that at 800 feet up during the Canadian winter.”

The design goal, he said, was to come up with a new curtain wall assembly that would bolster the building’s integrity while maintaining the stately appearance of the original design by Edward Durell Stone’s office and Bregman + Hamann Architects.

MdeAS had worked on Stone buildings before, notably New York’s General Motors Building. As with that project, the architects were drawn to Stone’s affinity for recurring geometric patterns. On First Canadian Place, they added a ceramic frit to the custom seven-by-ten-foot Viracon glass panels, evoking the texture of the original marble with a series of triangles.
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Each of the new opaque spandrel glass panels replace eight marble tiles, extending beyond the corners of the building on all sides. “Rather than just having the white glass fold back into these corners that were important to the original design, we used the contrasting glass color to make spandrel glass, accentuating the corners,” said Shannon.

The subtle sheen and restored brightness of the curtain wall contrast strikingly with those shadowy corners. New solar-reflecting window treatments and repaired air leaks update the insulated glass units that remain from the original assembly. In all, the unitized spandrel panel glass system nests three panes of ¼-inch low-iron glass in an extruded aluminum frame, with three types of PVB interlayers between.

In place of the 45,000 marble panels now sit 5,370 glass panels, reducing the amount of cladding sealant needed by 39.8 miles. The removed marble is being crushed into roof ballast and sand for other projects, and a portion is going to local art programs.