Canadian War Museum
The 440,000-square-foot (40,860-square-meter) CWM rises up on 18.5 acres (7.4 hectares) of reclaimed brownfield that slopes up onto a 115,000-square-foot (10,672-square-meter) accessible grass-covered roof, the largest green roof in North America. The building is visually elusive and resists being taken in from any single exterior vantage point.
The Regeneration Hall's large tower cleaves the roof to an 80-foot (24-meter) pinnacle in the sky, clad inside with recycled copper sheeting from the recently renovated Library of Parliament.
The project is also impressive for its brief three-year gestation from design to construction completion. The tight schedule forced the architects to make adjustments on the fly to accommodate portions that were already built and made cost control especially challenging for construction management.
Molding Space in Concrete
The architectural team created a building that challenges the senses with angled concrete walls, floors, and ceilings. The angles of the interior concrete walls vary from 3 to 31 degrees — exterior walls adjacent to the river lean inward, and on the opposite side, facing the city, they lean outward.
"The interesting thing that many visitors to the museum have observed is that in some spaces, they feel that the floor is sloping where it isn't, and visa versa," says project architect Brian Rudy, associate at Moriyama & Teshima. He explains this as a forced perspective created by the inward slope of the walls.
"The angles were a great challenge for the design team to locate and accurately detail," explains Rudy. "We located most of the complex geometry using a working 3D computer model throughout the design and contract documents phase. In some cases, we located exact points in the building with GPS coordinates rather than traditional dimensions to grid lines."
He continues: "The concrete contractors had a lot of fun with the angles and they undertook it with great zeal and creativity. Steel buttresses and tension cables were used to hold many of the walls in place before the floor and roof slabs were in place to brace them. These bracing systems became works of art in themselves."
Construction used 41,856 cubic yards (32,000 cubic meters) of concrete weighing 108,000 tons (106,300 tonnes) and 3810 tons (3,750 tonnes) of rebar. It took about 180,000 person-hours to build and strip the formwork, and the most concrete used in a single day was equivalent to 200 truckloads.
Concrete was chosen as a primary construction material because it helps maintain constant interior air temperature, quality, and humidity, necessary to preserve displays and artifacts.
Guy Larocque, director of property management and security services for the Canadian Museum of Civilization Corporation, explains: "The thermal mass that concrete affords is really a stabilizing factor, in that if cooling or heating units fail, the building temperature stays constant longer."
The CWM has two layers of cast-in-place concrete on all the perimeter walls — an interior 12- to 20-inch (30- to 51-centimeter) structural layer and an exterior seven-inch (18-centimeter) veneer. Between these two layers are a vapor barrier and insulation, so that concrete is exposed on both exterior and interior surfaces.
The dew point was calculated to occur inside the concrete when the outside temperature plummets. This prevents water from condensing, freezing, and expanding inside the insulation layer where it could cause damage.
The concrete exterior is also considered to be one of the most secure materials available to protect Canada's national wartime treasures. The museum surpasses building code regulations for seismic design. Beyond practical reasons, concrete was chosen for its versatility and its ability to be left rough or polished to a marble-like finish.
Rudy explains: "Concrete was developed in three patterns: the board-formed ooze joint pattern used extensively, especially as the exterior finish; random plywood-formed that resembles a patchwork quilt or aerial photo of farmers' fields; and the memorial pattern which has an ethereal, almost tomb-like quality."
Cement Association of Canada president François Lacroix observes: "Concrete is the architect's modeling clay. It can assume virtually any form and finish that a designer can envision. Designers use concrete for its ability to be sophisticated and tactile, as revealed in the museum's theme of regeneration. Concrete is part of the art form itself — it can be sculpted in ways that belie its own weight and strength."
The Canadian War Museum has been designed to reveal the sacrifice, honor, and bravery inherent in a population that must fight for its freedom. This building will stand on guard for hundreds of years to deliver its important message to future generations — may their familiarity with war be limited to these national archives.
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Brant Scott is a freelance writer and marketing communications consultant who resides in Ottawa. The Cement Association of Canada is one of his clients.