Early Consultations with the Precaster
CPCI members promote early discussion between owners and designers with a local precast concrete manufacturer to discuss precast solutions and to ensure that all the features, benefits and correct details are incorporated into a design. The was the case with Carmine Brunone, Architecttura Inc., contacting Res Precast in the early stages of design development to determine the feasibility of using an architectural precast concrete wall assembly for the school addition they where commissioned to design.
The design architect had the task of fast tracking a school addition that would be in keeping with the existing load bearing masonry construction with both the desired aesthetic and structural capabilities. Construction of the addition would occur during early winter, a time that does not favour masonry construction. The discussions with Mr. Brunone determined that architectural insulated precast load bearing wall panels could be used in lieu of masonry to meet the strict time schedule and have the school addition opened on time. Precast sandwich wall panels incorporate insulation between structural concrete wythes, providing in this case, load bearing support for the roof structure, a superior building envelope and durable, functional architectural interior and exterior finishes.
Budget and Schedule Consultations
With very preliminary drawings, Res Precast provided a "not to exceed" budget and a drafting and engineering, production and erection time schedule. This provided a feeling of comfort with the architect that the precast industry would compete for the general tender work, and beat or exceed Res Precast's budget and schedule.
The architect could have achieved a masonry look on the exterior of the precast concrete panels by the use of a rubber form liner to imprint a masonry jointing pattern on the face of the panels. Subsequent colour staining of the brick's surface (while leaving the recessed brick joints grey) could have created the look of masonry construction to match the existing structure. However, it was decided to go with a complementary exposed aggregate finish on the exterior of the precast panels. The existing school building used reddish brown masonry construction. Precast samples were developed, not to match but rather to complement the colours, with a combination of both sandblasted and exposed aggregate finishes.
The design was completed in precast concrete and issued for tender in November 2003. Gulf Construction was the successful general contractor, who in turn contracted for the supply and installation of architectural precast concrete wall panels with Res Precast who's bid maintained the budget pricing provided during the design development stage. Res Precast mobilized to provide shop drawings in two weeks. Precast panels arrived on site by the end of January 2004 during a six week time frame.
With conventional construction, foundations are placed, steel is erected and roof deck is placed before the precast wall cladding is installed. In the case of Ecole Secondaire L'Essor, foundations were placed, then the load bearing insulated precast concrete wall panels provided the support system for the roof framing and decking (hollow core precast roof slabs could also have been used). Field installation took 4 days to complete. Steel joist and metal deck followed. The precast temporary support braces were removed once the steel deck was complete and the interior trades were mobilized on site.
The success of this project can be attributed to the speed of construction and the effective use of precast concrete insulated wall panels that were comparable in cost with masonry cavity walls.
Architect: Architecttura Inc. - Windsor, ON
Engineer: Aleo Associates Inc. - Windsor, ON
Contractor: Gulf Construction of Windsor Inc. - Tecumseh, ON
Precast Concrete: Res Precast - Innisfill, ON