Contemporary design transforms heritage building

By Kim Pham

628 St. Jacques is located opposite the Montreal Stock Exchange Tower, on the edge of Old Montreal. Condominiums and common services are spread over 36 floors above a two-storey heritage building dating from 1907, whose façade on Victoria Square has been completely restored, and that on Gauvin Street has been reconstructed.

Through its proportions and repetitive elements, the project is inspired by the Art-Deco style characteristic of certain emblematic buildings in the district. However, there is a clear difference be- tween the first levels and the following ones, between a desire for heritage integration (particularly ornamentation) at street level, and relating the new tower to the contemporary city and the distant landscape (clean lines and abundant fenestration).

The façade of the tower uses architectural precast concrete panels with the integration of laminated Beauval stones at the level of the nearby basilica. The warm, textured colour of the material is similar to that of the buildings in the Victoria Square, respecting the proportion of masonry and helping to integrate the building into its context. The combination of a lighter shade for the structural elements and a darker shade for the frames around the fenestration gives a shading effect to the façade.

A detailed study of the assembly of the precast concrete panels made it possible to conceal the joints while emphasizing the verticality of the project by creating vertical structural elements. The panels, tailor made with the help of an envelope expert, discreetly integrate the ventilation grilles.

One-to-one scale models were made to validate the choices of colours, patterns and finishes, but also to verify details of moisture and air tightness and thermal performance. The precast concrete components were then produced in the CPCQA-certified factory and de- livered to the site for installation.

The residence has more than 250 units, as well as a commercial space on the ground floor, a gymnasium on the third floor and a panoramic terrace equipped with a swimming pool, the highest in Montreal when it was designed. The interior design is inspired by the New York style (for the common areas in particular), enhanced with brass details. Several units and penthouses have different finishes to respond to a diversified clientele.

Kim Pham DPLG, OAQ, OAA, MRAIC is Partner Architect at NEUF Architectes Inc.

Prefabricated construction samples evaluate aesthetics and costs

By Steven Audet

The new 38-storey 628 St. Jacques condo offers a unique character through the use of precast concrete wall panels on the façade, some with natural stone cladding (Beauval limestone from Europe) combined with elements having a concrete finish.

Complete windows were installed at the BPDL manufacturing plant, which has a production section specially designed for this operation as well as the personnel authorized to do the work that would normally be done on site. In addition, factory installation of the windows improves quality since caulking tasks are performed in a controlled environment protected from the weather.

The Beauval stone used for certain elements was also incorporated directly into the factory production process of the precast concrete panels. Special anchors on the back of the stone and the use of an insulating membrane to minimize the contact between the natural stone and the concrete resulted in high-performance, high-quality façade components which, again, reduced installation time.

Factory prefabrication involves creating a series of construction samples to evaluate the desired aesthetic effects and how they meet the budget. In addition, factory installation of the windows improves quality since caulking tasks are performed in a controlled environment protected from the weather.

In the case of 628 St. Jacques, the exposed concrete followed two compositions: one with a white cement base and pigments added (beige finish), and another with a grey cement base and black pigments (black finish), all treated with sand spray. The mixtures provide sufficient contrast to meet the effect sought by the architects, while incorporating the Beauval stone used on some of the prefabricated concrete elements. To the observer, the final effect blurs the boundaries between the window frames, ventilation louvres and the precast concrete panels.

When designing the reinforcement and thickness of the precast concrete panels, the BPDL engineers considered the weight on the foundations and the capacity of the on-site lifting crane so that the panels were not heavier than necessary. For example, in this project, the large openings for the windows made the concrete sections of the "punch-window" panels thinner and therefore presented a challenge for the engineers.

Steven Audet is a Project Manager at Béton Préfabriqué du Lac (BPDL).
Photos: Alex St Jean/NEUF Architectes and BPDL