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AUGUST 2019 | 9 Building Envelope PHOTOGRAPHY COURTESY READ JONES CHRISTOFFERSEN; LAFARGE; RENDERING BY W. T. LEUNG ARCHITECTS INC./COURTESY ENGINEERED ASSEMBLIES INC. Building envelope products for high-performance buildings by ROBIN BRUNET A s 2019 progresses, a host of experts who could be described as build- ing envelope specialists are involved in a wide array of projects aimed at maximizing energy efficiency, as well as creating building exteriors that are esthetically pleasing. While there are many ways to achieve this, Brian Hall, managing director of the Canadian Precast Prestressed Concrete Institute (CPCI), thinks the best method is precast – whether the system is solid, thin shell, or insulated sandwich wall panels. "With the advancement of energy codes, designers are approaching envelope design differently," he says. "In a growing number of regions, envelopes must provide continuous insulation and a continuous air barrier. Envelopes are also required to provide a vapour barrier to control condensation and indoor humidity, as well as avoid compromising the insulation system. "Precast concrete's edge-to-edge insulation, combined with the non-conduc- tive connectors between the interior and exterior concrete layers, can create an efficient thermal break that prevents heat and moisture from penetrating the building and eliminates thermal loss and vapour transmissions present in other wall assemblies." Fred Edwards, an associate at RJC Engineers, describes his firm's Calgary office as routinely being involved "in the lifecycle renewal of envelopes, and we use the knowledge we gain from such projects and apply it in other projects that require the development of new envelopes." One project of note is the new SODO apartments in Calgary, which consists of two 30-storey towers (one for the apartments, the other a hotel) on a four-storey podium. "The podium is noteworthy in that on the residential side it contains a parkade and on the hotel side it contains amenity space," says Edwards. "We used precast concrete sandwich panels to provide a uniform cladding around the entire base, with a custom fabricated form liner for a random stone masonry finish. This type of envelope gave the parkade the durability it required, and for the amenity side we used interior finishes on the reverse side of the sandwich panels." RJC Engineers also ensured that the joints would function as a rainscreen, something that was accomplished by developing dual stage sealant joints with weep holes. Another noteworthy project for RJC Engineers was the Christine Meikle School, a special needs facility that features a full-sized swimming pool in the centre of the building. "This presented a sizable envelope challenge," says Edwards. "We wound up using a conventional roof with a traditional rainscreen wall cladding, increased the amount of exterior insulation from the standard four inches to six inches, and installed thermally broken cladding supports in order to increase energy efficiency." Jason Rabasse, business development manager, precast, Western Canada, for Lafarge, cites the Stradbrook apartments in Winnipeg as an example of his com- pany using precast as the envelope system of choice. "The Stradbrook's 18-storey apartment building plus three storeys of parkade is what the industry refers to as a total precast structure entirely made up of precast elements, including the stairs, stair shafts, elevators shafts, floors, and exterior insulated wall panels," he says. "We can use two types of panels: precast as a cladding panel tied back to the floor structure, or as load bearing insulated wall panels to transfer building loads down through the building's exterior to the foundation. The owners opted for a smooth finish with minimum reveals, although with precast a huge variety of finishes, formliners, and even photo etching are possible." From Top To Bottom Darren Smith, national sales manager Canada/U.S. for Engineered Assemblies, discusses how his firm is providing a full thermally broken facade for ViewStar, a series of six high-rise buildings in Richmond designed by W.T. Leung Architects Inc. "We have 84,000 square feet of facade materials on the project, and about half that amount features our Equitone Tectiva high-density fibre cement," he says. "The other half features our Tonality ceramic clay tiles." With a full assembly, including the TcLip to provide a thermally broken sub- structure, the six towers will exhibit a mix of three colours in Tonality utilizing a vertical stacking joint to allow for a quick install. The lower levels will feature the robust Equitone Tectiva in primarily larger panels, with the use of colour- matched rivets. "Tonality is ideal for high-rise projects, and in the right design it can be installed extremely quickly, thus reducing labour costs," says Smith. Stone masonry finish, SODO apartments, Calgary, AB. Stradbrook apartments, Winnipeg, MB. ViewStar, Richmond, B.C.

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