In response to its site, the new Halifax Central Library will have a twisted geometry, including more than a dozen cantilevers. © schmidt hammer lassen architects
Featuring more than a dozen cantilevers, a new library in Halifax, Nova Scotia, Canada, brings contemporary design to a community steeped in history.
February 11, 2014—Downtown Halifax, Nova Scotia, Canada, is replete with rich history and 200-year-old buildings. But a new library is under construction there that will be decidedly different from its Georgian-style neighbors. In lieu of a traditionally shaped building, the library will appear as four stacked and staggered volumes—an arrangement that is designed to respond to the site and reflect contemporary society. Achieving the building’s complex geometry, including more than a dozen cantilevers, has required a great deal of analysis and structural detailing.
The Halifax Central Library is being constructed at the corner of Queen Street and Spring Garden Road on a site that once featured Bellevue House, a mansion built in 1801 that served as the residence of the British Army’s commander in chief of Halifax. The approximately 16,000 m2 library will replace the existing central library, located across the street, and will have seven levels, including an underground parking level and an upper mechanical level. The first level will have a community hall, a cafe, book shelves, and a circulation desk; levels two through four will have book shelves and seating areas; and the fifth level will have a cafe and a seating area with couches to be known as the Halifax Living Room. Each level will open to a central atrium and will be connected by a grand staircase, which will have a sculptural form as it meanders up through the building.
Each of the library’s above-grade levels will open to a central
atrium and will be connected by a meandering staircase.
© schmidt hammer lassen architects
The Halifax Regional Municipality advertised a request for proposals for the new library in the winter of 2009. Design firms from across the region and around the world responded, and as the result of a qualifications-based competition, the municipality awarded the project to the team of schmidt hammer lassen architects (SHL), a design firm headquartered in Copenhagen, Denmark, that is known for designing cutting-edge libraries, and Fowler Bauld & Mitchell (FBM), a design firm headquartered in Halifax that is well established in the region. SHL is the lead designer and FBM is the architect of record on the project. The structural engineer is SNC-Lavalin, an international engineering and construction firm headquartered in Montreal, Quebec, which bid on the project from its Halifax office as part of the design team.
The municipality wanted a state-of-the-art building that would reflect the community and its future aspirations. To that end, the designers held several meetings during which community members shared their vision for the library and provided input as the design evolved. As a result, the library will feature a design that is inviting to people throughout Halifax’s diverse population—an important factor because libraries are becoming the so-called “third space” in which people spend their time, says Morten Schmidt, AIA, a founding partner of SHL. “We have our work, where we spend a lot of time, and we have our home, but today people don’t have that many other places where they go, except very commercial places like shopping malls,” Schmidt says. “But the library becomes a place where you would go as a noncommercial space. And we call this the third space.”
The designers were also influenced by the library’s site, which is bordered by nonorthogonal streets and is within an established view corridor from the Halifax Citadel National Historic Site, a former British military fortification that overlooks downtown Halifax and nearby Halifax Harbor from what is known as Citadel Hill. In accordance with municipal bylaws, the view corridors from The Citadel to the harbor must remain unobstructed, and therefore any buildings located within those corridors are subject to height restrictions. The site’s asymmetrical configuration defined the library’s twisted form, and the view corridor restrictions dictated that the library’s top level be smaller than the levels below, Schmidt says. “You must be able to see the horizon of the ocean and the harbor from The Citadel [along these established view corridors],” he explains. “And one of these view corridors from The Citadel crosses exactly through our building, so we couldn’t go up on the fifth level for half of the building. And that’s why the building has this look of this bar that sits on top of it.”
The library’s top level, known as the Halifax Living Room, will
afford views across the city and to the nearby harbor. It will be the
first public building to offer such views. © schmidt hammer
A combination of concrete and structural steel is being used to achieve the library’s distinct geometry. The building will be founded on conventional cast-in-place concrete walls and spread footings that bear on bedrock. The floors, the stair and elevator cores, and the main roof will also be framed in concrete, while the cantilevered roofs, mechanical room, and cantilevered Halifax Living Room, located in the building’s top level, will be framed in structural steel. “Concrete was selected as the structural material of choice for the majority of the building framework for its resistance to fire, sound-dampening quality, and ability to achieve proportionately long spans with relatively thin floor structure depth,” said David Bulger, P.Eng., a senior structural engineer for SNC-Lavalin, in written responses to Civil Engineering online. “Structural steel was selected as the material of choice in areas that called for heavier loading and long cantilevers.”
The library will have approximately 14 floor and roof cantilevers, ranging from 1 to 8.7 m long. Most of the cantilevers will be achieved by allowing the concrete floor and roof slabs to extend past their support lines, with moment-frame connections at certain locations. However, the largest cantilever, which will extend the Halifax Living Room 8.7 m beyond the lower levels, is being achieved using two custom-designed structural steel Vierendeel trusses to meet flexural and stability requirements without being too architecturally intrusive, Bulger said. “The two most unique features of the building from a structural perspective are considered to be the offset floor plates and the Vierendeel-truss-framed cantilevered space that projects out beyond the building footprint,” he noted. “These elements required a reasonable amount of analysis and detailing and are not building features that are commonly seen.”
The entire building will be clad in a premanufactured curtain wall system comprising glazing and structural mullion framing. Premanufactured anchors cast into the concrete floor and roof slabs will anchor the curtain wall system to the structure. Additional premade clips will attach the mullions to the anchors and allow the curtain wall system to bear on both the foundation walls and elevated concrete floor slabs, Bulger said.
The library will feature a great deal of community space for
meetings, performances, and other events. © schmidt hammer
Roughly half of the curtain walls will be insulated to meet energy code requirements. All of the insulated panels and some of the uninsulated ones will feature a silk imprinted leaf pattern, recalling the spring garden at Bellevue House. The building’s fourth level will be clad in orange-tinted curtain walls—an eccentric feature that lends inviting warmth to the structure. The cladding system will afford views into and out of the building at every level, the top-floor living room and its adjoining garden roof providing particularly stunning views of downtown Halifax. “Visitors will have views of the harbor and views to Citadel Hill,” says George Cotaras, the president and general manager of FBM. “These are views that you can’t currently get from a public building.”
Construction is expected to be complete in July, and the library is scheduled to open in early November. The designers hope the library becomes a beloved gathering place as well as a model for contemporary architecture in downtown Halifax. “People think new buildings should look like the old ones and that attitude has been prevalent for a long time,” Cotaras says. “But this project shows that a very modern building can exist against a very old, traditional building, and they’re compatible. I think this will change people’s attitudes about architecture.”