Espace CDPQ - Architectural Stairway | ELEMA - Structural Engineering Firm

Client :Ivanhoé Cambridge
Architecture :Lemay
Photos Credits :Claude-Simon Langlois

The CDPQ Entrepreneurial Space, an international investment and support center for Quebec SMEs, is located on the ground floor of Towers 2 and 3 at Place-Ville-Marie in Montreal. With a total surface area of 5,110 m² (55,000 ft²) spread over two floors, this prototypical and experimental space puts the latest trends in collaborative work environments at the forefront and offers occupants an immersive built-up ecosystem, a facilitator creative thinking.

ELEMA was given the mandate to design the architectural staircase, one of the centerpieces of this new space. The spiral staircase is 3.35 m (11 ft.) in diameter, supported by a 610 mm (24 in) central post, and is entirely made of steel. The staircase links the two floors of the CDPQ Entrepreneurial Space.

Technical challenges :

Construction work on the second floor had to be done once the occupants moved to the ground floor. Therefore, all the reinforcement and slab cutting of the opening in the floor was planned beforehand to mitigate disruptions in the occupied space.
The installation of the monumental staircase was made in a narrow and busy environment. Although most of the work was done at night, some construction methods had to be developed so that the work was done from the 2nd floor.
Installation of the reinforcement for the existing floor slab of Espace CDPQ in the ceiling of the underlying commercial gallery was done without service interruption of the businesses.

Notable solutions and innovations :

The profile of the spiral staircase is extremely smooth, making the stair structure very sensitive to vibration. Very precise numerical analyses were required to develop a structural system utilizing the steps and the ribbon-shaped peripheral form.
Development of the sequence of construction of the staircase in situ with the specialized subcontractor.

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