The Grand Théâtre de Québec is an iconic building with several performance halls and offices built in 1971. The building features repeating modular elements constructed from precast concrete that form the exterior facing. On the interior side, the Jordi Bonet mural graces a significant portion of the surface opposite to the concrete panels, presenting a remarkable sight for visitors to behold.
After decades of exposure to its environment (humidity, condensation and water infiltration), the envelope had deteriorated and required intervention. The presence of water, combined with air and repeated freeze and thaw cycles, had accelerated the corrosion process of the anchors and reinforcing bars of the concrete panels and caused the concrete to burst.
To ensure the building’s long-term sustainability, the Grand Théâtre de Québec needed to remedy the deteriorating outer shell. The conventional practice to resolve the problem would have been to improve or replace the existing envelope by installing a new pressure-balanced rainscreen enclosure. However, wanting to preserve and enhance the brutalist architecture of the building, the integrated team comprising WSP in Canada (engineering services), the Lemay-A21 architecture consortium (design) and Pomerleau (contractor) put forward an innovative proposal to create a ventilated double façade.
The proposed approach involved implementing an envelope formed of encircling glass offset from the building, resulting in the existing outer shell of the Grand Théâtre constituting as the first layer of the ventilated double façade. This would create an interstitial air space and optimal conditions that would be continuously maintained by mechanical ventilation and a heating system that protects the existing concrete envelope from degradation while preventing condensation on the glass. Finally, lighting solutions would be used to allow for the preservation of the building’s aesthetic.
The simplicity of the gesture made it possible to keep the first layer of the double façade (i.e., the existing façades) while reducing the visual impact of the intervention. The protective glass layer, including the steel support structure, allowed for a fine and elegant look while leaving plenty of room for the structure and architecture of the original building.
Opting for a minimalist intervention, in comparison to a reconstruction, also allowed for additional environmental savings. As the renovation involved keeping the existing envelope, the new materials needed for the project resulted in being mainly limited to glass, steel structure and electromechanical components and the amount of waste linked to the project was limited.
The solution created by WSP in Canada and its partners allowed the brutalist design to still resonate on the exterior while protecting important interior elements of the building, including the Bonet mural.
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