Sid Lee Architecture and ADHOC Architectes Stack a Grid of Glass Cubes onto a Montréal Church

A church becomes a recording studio becomes 46 apartments. That is the compressed biography of the building at 1115 Square-Amherst in Montréal's Centre-South borough, where Sid Lee Architecture and ADHOC Architectes have grafted a five-storey residential volume onto the bones of the former All Nations Church. The site spans a full block bound by Sherbrooke Est, Wolfe, and Atateken streets, directly facing the northern entrance of Marché Saint-Jacques. It is a tight, setback-heavy, three-street-fronting parcel that would intimidate most developers into a bland box. Instead, the architects produced a checkerboard of stacked glass cubes that makes the heritage building look not diminished but celebrated.

What makes Carré des Arts genuinely interesting is not the fact of adaptive reuse, which has become Montréal's favorite genre, but the precision of the seam. The new volume does not float above the church or politely step back from it. It wraps around and rises from it, using double cantilevers and meticulous structural coordination to connect contemporary steel and glass to ornamental brick without flattening either vocabulary. The result is a building that reads differently from every street: heritage wall on one side, luminous residential grid on another, and a dialogue between the two wherever they meet.

The Grid as a Human-Scale Strategy

Seen from street level, the new residential volume reads as a matrix of cubes: some pushed outward as loggias with wooden-clad balconies, others recessed as bay windows. The alternation gives the facade depth and rhythm without relying on applied ornament. Each cube corresponds roughly to one living unit, which means the exterior communicates occupancy at a glance. You can count homes. That legibility is rare in a five-storey building, and it keeps the project from feeling monolithic despite its considerable footprint across the block.

At the ground plane, hexagonal planters and seating create a modest public threshold along the cantilevered edge, softening the transition from sidewalk to private entrance. Pedestrian and vehicular access had to be painstakingly choreographed on a cramped site with complex setbacks, and the landscaping does double duty as buffer and amenity. The twilight views reveal how the glazed cubes glow individually, turning the facade into a lantern grid that animates the streetscape after dark.

Heritage Brick Meets Glazed Volume

The rear elevation is where the collision of eras is most legible. Dark-paneled volumes rise directly above the preserved red brick walls of the former church, and the dusk light sharpens the material contrast to almost cinematic effect. Ornamental brick treatments, peace symbols embossed in the facade, and a massive original door have all been retained. These are not token gestures; they anchor the project's identity to its ecclesiastical past and save it from the generic "heritage conversion" label that plagues so many similar efforts.

The construction required what the teams describe as inventive strategies developed on site: resolving junctions between old masonry and new steel, threading thermal insulation through irregular wall assemblies, and managing structural loads where a double cantilever meets century-old brick. CPF Groupe Conseil engineered the structural solution, while SP Génie Conseil handled electromechanical systems. The coordination between disciplines was not just logistical but aesthetic. Every junction had to be precise enough to read as intentional design rather than awkward compromise.

Light and Interiority Through the Cube Matrix

The stacked-cube grid is not only a facade gesture. It organizes interior space by giving each unit generous openings on at least two sides, producing the luminous, open layouts that the architects set out to achieve. The alternation between inward bay windows and outward loggias means that no two adjacent units share the same relationship to the street, which introduces variety into a rental typology that often defaults to repetition. Wooden balcony surfaces add tactile warmth to an otherwise crisp material palette of glass, metal, and brick.

At 34,154 square feet distributed across 46 units, these are compact homes. The small-unit strategy is itself a design decision: it lends human scale to the architectural composition and increases density without overwhelming the neighborhood. In a borough where housing pressure is acute, packing more front doors into a single block is a civic contribution as much as a formal one.

Plans and Drawings

The section drawing reveals the staggered floor plates that produce the cube effect on the exterior, along with a central circulation core that keeps corridors short and maximizes perimeter living space. Trees flanking the building in both section and elevation suggest that the landscape strategy extends beyond the ground-level plaza to frame the building within its streetscape context.

The elevation sketch showing a multilevel scaffolded structure adjacent to arched openings is a fascinating document of the construction logic: the new grid literally frames the old church's apertures, using them as compositional anchors rather than obstacles. The floor plan confirms that residential units wrap around a central atrium and dual stair cores, a layout that maximizes natural ventilation and daylight while meeting egress requirements on a site that offers no easy rear yard.

Why This Project Matters

Carré des Arts matters because it refuses the two lazy defaults of heritage conversion: the glass-box-on-a-plinth approach that treats the old building as a pedestal, and the facadism gambit that keeps the front wall and demolishes everything behind it. Here, the old and new volumes genuinely interlock, structurally and spatially. The checkerboard grid gives the addition its own architectural identity without competing with the brick church below, and the retained peace symbols and ornamental masonry keep the site's cultural memory intact at eye level.

For Montréal's Centre-South, which is in the middle of a complicated densification, the project offers a model: high-density rental housing that engages three street fronts, contributes ground-level public space, and treats a constrained site as a design opportunity rather than an excuse for compromise. Sid Lee Architecture brought the conceptual ambition; ADHOC Architectes brought the execution rigor. Together they produced a building that earns its name. It is, genuinely, a block where art and engineering meet.

Carré des Arts by Sid Lee Architecture (concept architect) and ADHOC Architectes (execution architect). Located in Centre-South Montréal, Québec, Canada. 34,154 sq ft across 46 residential units. Completed 2023. Photographs by David Boyer.

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