In what used to be a quiet corner of Winnipeg, a series of large new housing communities Continue to grow in a still-healthy Winnipeg housing market, a sign of a diversified Manitoba economy that has been weathering the financial storm relatively well. Sage Creek Village occupies what was once farmland in southeast Winnipeg, and adjacent to the new development stands the new corporate headquarters of The Qualico Group. The building is to be the focal point of a future grouping of shops and cafes that will serve the neighbouring residential community.
To that end, and in keeping with the small-town feel Qualico is after, the building will stand just three storeys tall, encompassing some 95,000 sq ft and include an underground parking facility. The new head office is targeting LEED® certification, and will demonstrate Qualico’s corporate commitment to the concept of all things green, including first-rate air quality that should help its staff stay healthier and, by extension, more productive. The building has been designed with an eye to solar orientation in order to maximize daylight on the south and east, while limiting exposure on the west and north sides, as well as employing an energy efficient heating and cooling system.
In keeping with the LEED aspirations, a large portion of the structure is also constructed of precast concrete. “We knew we wanted a concrete structure because of the thermal mass,” explains Dennis Kwan, Associate at Prairie Architects Inc., and team leader on the Qualico project. “It’s important from an energy point of view because it helps to even out the temperature in the building over a long period of time. Precast, of course, turned out to be a very economical, and a very precise way of achieving that concrete structure.” In fact, the project involves a broad range of precast products including 9,200 lineal feet of piles, 55,500 sq ft of 8-inch hollow core, 6,700 sq ft of 12-inch hollow core, 52-columns (one piece, full-height), 72-inverted tee-beams, 55-spandrel beams and 30-wall panels, four of which had a column built right into the panel.
One of the unique features of the Qualico project is the incorporation of two living green roof terraces: one on the second floor, and one on the third floor that can be used for entertaining or meetings, and which will have hard-surface areas as well as planted areas. And the use of precast allowed for intricate notching in the precast columns so that the terrace surfaces could be dropped lower than the floor areas. “These were necessary because of the thickness that we were anticipating for the roof insulation,” notes Kwan, “plus the thickness of the green-roof planted areas, and of course, in the end, you want the finished level of the green-roof pavers to be level with the interior floor in order to be barrier-free in terms of wheel-chair access.”
The use of precast also enabled other fundamental design characteristics of the Qualico building including the use of long clear spans, achievable because of precast’s ability, when reinforced, to carry more load. This was also of particular advantage with the rooftop green spaces, which could have created significant issues were it not for the use of precast. “Had we been forced to create the building out of steel or some other material,” says David Poole, structural designer at Tower Engineering, “we certainly would have been into a severe headroom crunch. Precast allowed us to make allowances for the green-roof details, and to carry those loads without really impacting the overall building height or the usable space.”
In fact, that was an advantage of precast for the building overall, emphasizes Brian Cornelsen, project manager at StreetSide Development Corporation, a subsidiary of Qualico. “Because the precast beams are smaller than conventional concrete beams would have been,” he says, “we were able to gain more headroom in some locations – the parking garage, specifically, but also on all of the floors.”
From a design perspective, a large amount of time was spent by the precast engineer assisting the structural engineering consultant in formulating a building layout that was suitable for the use of precast. The goal was to design the building to suit precast concrete, rather than design the precast concrete to suit the building, thereby optimizing the design. “In one case, we had some precast columns where we had several beams tying into the column on different faces, and from four different directions, ”says Poole,“ and it got quite congested, but by Lafarge using TEKLA program Building Information Modeling Software (BIM), we were able to pick up on a lot of the conflicts and to resolve the vast majority of them before they actually even got into the casting process.” Using the BIM program, designers were able to model the column in three dimensions, and input provided information regarding desired connection plates, reinforcing for the corbels for the precast beam, stirrups, and the actual rebar for the column itself.”
The use of precast also provided the flexibility to allow designers to react to an evolving building code. When structural designers began working on the project’s lateral resisting system, they were working under the 2005 NBC, which included requirements for seismic design. However, in the middle of the project, that requirement was repealed, allowing the team to take advantage by eliminating some additional bracing that it would have otherwise incorporated to resist the seismic loads. Ultimately, they used the stair shafts – a precast wall system – as a major lateral load resisting system. “What it enabled the architect to do,” says Poole, “is create a very open elevation all the way around the building without having members crossing through the windows.
That was a particular advantage because, with the LEED certification they were going after, the daylighting into the interior of the building is quite important for some of those credits. Being able to get rid of solid walls on the outside of the building as well as that cross bracing was made possible through the incorporation of precast.” Ultimately, the key to working out a lot of these challenges, and to maximizing the advantages of using precast in the first place comes down to proper planning. “We’re into winter construction,” says Kwan, “and the speed of assembly on-site was a major bonus.
There was a lot of time spent in the preparation and the shop-drawing stage, but that paid off when it came to actual work on site. With precast, a little extra work in the early stages pays off in a big way later on during the erection stage.” Cornelsen points out that while they were preparing the foundation, the precast building components were being fabricated at the same time, speeding up the overall construction schedule. When everything was ready to go, Lafarge field staff began erection of the precast structure in early July of 2008 and placed the last piece by mid-September. “Compared to cast-inplace concrete,” Cornelsen speculates, “we could have easily saved ourselves a month on the construction of our parking garage alone.” Construction of the $22 million Qualico headquarters was expected to be complete by the fall of 2009.
Owner/General Contractor: StreetSide Development Corporation, A QUALICO Company
Architects: Prairie Architects
Structural Engineers: Tower Engineering
Precast Concrete: Lafarge Construction Materials – Precast Division