Since opening in 1984, L’Octogone Library has occupied a distinctive but inward-looking building in Montréal’s LaSalle borough. Its octagonal form gave the institution a recognisable identity, but the original layout offered few connections to the surrounding streets, public spaces, and Félix-Leclerc Park.
An expansion by Anne Carrier Architectes and Labonté Marcil architectes, two Québec architecture practices working as a consortium, increases the library’s total area from 2,645m² to nearly 4,500m². The original structure has been retained, with three new volumes, described by the architects as lanterns, facing different parts of the site.
The project followed an architectural competition launched in 2017 to rethink the building as a contemporary cultural institution. The brief called for an accessible, flexible, and sustainable library that could accommodate learning, creative activities, and civic life while preserving the original building’s identity.
Three lanterns connect the library with LaSalle
Each lantern is oriented towards a different part of the site and houses a distinct set of functions.
At the north-east corner of Dollard Avenue and Salley Street, the Urban Lantern rises above the library’s administrative and support areas. Its transparent façade reveals workspaces framed by openings based on comic-strip panels.
The Pastoral Lantern extends south-west towards Félix-Leclerc Park and the Aqueduct Canal. Its structural rhythm follows the octagonal volume below, while a projecting frame contains naturally lit reading areas and a large outdoor terrace.
Facing south-east, the Community Lantern connects with the entrance and outdoor areas around the building. It houses the café, news lounge, and Fab Lab, with adjoining terraces and lounges extending these uses outside.
The additions connect the library’s internal functions more directly with the surrounding streets, terraces, and park.
Original octagonal structure retained
The architects retained the library’s principal volume and added another floor, increasing its area without substantially enlarging its footprint.
The octagonal structure remains visible within the expanded building and determines the geometry of parts of the addition. The existing concrete slab and sections of the structural frame are also reused.
Retaining these components avoided up to 261,000kg of CO₂ emissions and diverted 870m³ of construction waste from disposal.
Perforated metal and transparent façades distinguish the additions from the original volume while respecting the scale of the existing building.
Central hall links the street and park
Visitors arriving from Dollard Avenue cross a public forecourt before entering a large central hall. From here, routes lead to the library’s programme areas and Félix-Leclerc Park, while a sculptural staircase provides access to the upper levels, rooftop terraces, and gardens.
Internal viewpoints look across the library and towards the sky. Reading rooms are joined by meeting spaces, interactive areas, flexible activity zones, a café, and a Fab Lab.
The circulation follows an ascending sequence influenced by elements of LaSalle’s history, including the Lachine Canal and Fleming Windmill.
One of the upper-level destinations is Dans ma bulle, a suspended reading area above the central space. The staircase leading towards it incorporates En circulation, an artwork by Karilee Fuglem. Elsewhere, a living wall takes its composition from The Great Wave off Kanagawa.
Comic-book collection shapes the interiors
L’Octogone Library’s comic-book collection influenced the interior geometry, furniture, wayfinding, and staircase. Comic-strip framing also appears in the openings of the Urban Lantern.
Inclusive signage and adaptable layouts support accessibility, while the transparent lantern façades bring natural light into the reading and community spaces.
The project is pursuing LEED Gold certification. Its environmental measures include a high-performance envelope, passive design strategies, energy recovery, and efficient mechanical systems. The project team reports an energy reduction of more than 30%, although the comparison baseline is not specified.
