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RAIC Innovation in Architecture Award Winner: Grand Théâtre de Québec, Quebec City, Quebec

"The Grand Théâtre de Québec demonstrates a host of notable innovations in the spirit of honouring the original Victor Prus building and sensitively protecting the existing degrading structure and Jordi Bonet mural."

A glass envelope fully encapsulates the heritage theatre, halting the deterioration of its concrete structure. Photo by Stéphane Groleau

ARCHITECTS Lemay / Atelier 21

PHOTOS Stéphane Groleau

Since its grand opening on January 16, 1971, the Grand Théâtre de Québec has been a prized cultural icon in Quebec City. The building is admired for its brutalist architecture, by Victor Prus, who designed it as a solid box made of prefabricated concrete panels, with a projecting roofline, sides subtly canted inwards, and transparent base. The architecture is entwined with an integrated artwork—a monumental concrete mural by sculptor Jordi Bonet that covers close to 60 percent of the interior, making it one of the largest sculptures of its kind in the world.

By the turn of the century, moisture had caused the concrete panels’ steel anchors to disintegrate, threatening both the exterior envelope as well as the interior mural, both of which are linked to the structure. The concrete anchors could not be simply removed and replaced. An innovative solution was urgently needed to protect the building’s heritage elements.

One of the world’s largest artworks made of sculpted concrete is integrated with the existing structure. The sculpture, which could not be removed, is protected by the intervention. Archival photo courtesy Grand Théâtre de Québec

To halt the corrosion of the anchors, Lemay and Atelier 21 worked to create a transparent exterior envelope that would fully encapsulate the building—a North American first. The box adapts to the building’s unusual shape, adopting its structural logic and composition in order to quietly surround the original architecture.

Because of the heritage building’s fragility, designing and constructing the envelope was a complex endeavour. The project had to stay open throughout the process: construction noise could not interrupt shows or rehearsals, architectural and technical solutions could not hinder building access, and interior spaces were off-limits. Since the interior mural was connected to the exterior concrete panels, any operation had to have zero impact and vibration on the existing envelope. Coordination with several levels of decision-makers was essential. Weather conditions were also a major challenge: installation of the new envelope was only possible under specific climatic conditions, when it was sufficiently warm and without strong winds. Finally, because the new glass panels needed to be precisely attached to a steel armature, the steel could not be exposed to any significant temperature variation from the moment of its final assembly to the installation of the glass.

Photo by Stéphane Groleau

The construction systems were almost all custom designed. The delicate steel structure on which the glass rests is the result of intense and sustained teamwork among architects, engineers, construction specialists and manufacturers. The custom fabricated fasteners have a minimal visual impact, with only a small 200 mm x 200 mm aluminum square visible, maintaining the transparency of the new protective layer. The construction system also had to allow for maintenance, which is achieved with a suspended platform inserted in the two-metre void between the existing building and the new envelope.

The construction uses 900 ultra-clear laminated glass panels, each of which weighs a half tonne. They are supported by four fasteners at their corners, composed of two exterior plaques that cinch against the glass, and an intermediate stainless steel component that connects to the new steel structure and allows the panel’s alignment to be adjusted. Positional accuracy within two millimetres was achieved through techniques used for the first time in North America. For instance, two-tonne sand trays were suspended at the bottom of the structure to simulate the weight of the glass plates before they were affixed, allowing for workers to ensure the structure was precisely positioned before attaching the glass. Each time a panel was installed, ballast was removed to maintain the final position of the whole structure.

Typical bay. Drawing courtesy Lemay / Atelier 21.

The secondary, tempered air layer created by the new envelope allows for a low-flow heat recovery system, increasing the building’s energy efficiency. Computational fluid dynamics (CFD) simulations and energy simulations were undertaken to ensure that the air temperature within the construction void could be maintained at a minimum of five degrees Celsius. The structural elements required additional tests, including testing of the joints between the glass panels, which led to the development of a bespoke silicone joint base.

Plan, Section and Assembly Drawing. Courtesy Lemay / Atelier 21.

As we face more challenges related to the preservation of modern heritage, the refurbishment of the Grand Théâtre de Québec provides a set of technical solutions that may be applicable to other projects. Moreover, it models a transdisciplinary approach, in which architects, structural engineers, mechanical engineers, architectural historians, manufacturers, and other specialists work together to push boundaries and find cost-effective, low-impact tactics. The result is a simple, efficient solution that responds to the particular technical needs and aesthetic expression of Victor Prus and Jordi Bonet’s theatre. The building’s striking brutalist lines and artistic narrative are not only preserved, but are ultimately enhanced by this subtle, functional and environmentally advanced solution.

Photo by Stéphane Groleau

Jury Comments ::  The Grand Théâtre de Québec demonstrates a host of notable innovations in the spirit of honouring the original Victor Prus building and sensitively protecting the existing degrading structure and Jordi Bonet mural. The new glass casing is quiet and understated, with a technical rigour that speaks to what must have been remarkable teamwork between the architects, engineers, and manufacturers. It skillfully addresses the challenges faced by the concrete façades and unique interior sculptural murals by developing from the exterior a meticulous envelope system and creating an in-between controlled environment. The team’s choices throughout the process demonstrate how intelligent, quiet innovations can significantly extend the life of public buildings for the betterment of the community, climate and environment.

The jurors for this award were Pat Hanson (FRAIC), Michael Green (FRAIC) and Leila Farah.

CLIENT Grand Théâtre de Québec | ARCHITECT TEAM Lemay—Eric Pelletier, Gabriel Tessier, Sarah Perron Desrochers, Amélie Turgeon, Olivier Boilard. Atelier 21—Christian Bernard, Mathieu Turgeon, Antoine Carrier, Jacques Berrigan, André Dagenais, Élie D. Carrier, Marc Leblond. | STRUCTURAL/CIVIL WSP (Olivier Marquis) | GLASS/FIXTURE DESIGN ELEMA consultants (Félix Bédard) | MATERIALS SIMCO | MECHANICAL/ELECTRICAL WSP (Jean Gariépy) | CONTRACTOR Pomerleau (Sébastien Couillard) | STEEL STRUCTURE Métal-Presto (Claude Roseberry) | GLASS MANUFACTURER Viterie Laberge (Jean-François Berthiaume) | LIGHTING Lemay / Atelier 21 + Guy Simard architecte | LANDSCAPE Lemay / Atelier 21

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