Owner
University of Toronto
Toronto, Ontario, Canada

Project Engineer/
Designer
Read Jones Christoffersen, Ltd.
Toronto, Ontario, Canada

Repair Contractor
Alliance Restoration, Ltd.
Toronto, Ontario, Canada

Material Supplier/
Manufacturer
BASF
Toronto, Ontario, Canada

This parking garage, located at 252 Bloor Street West in Toronto, ON, Canada, is a 10-level (split-level) underground structure located directly below the University of Toronto’s Ontario Institute for Studies in Education (OISE) that provides parking for approximately 250 vehicles. Large-scale corrosion-related concrete deterioration in the form 
of concrete spalls, rust staining, and surface delaminations were evident throughout the entire garage. The corrosion-related concrete deterioration was extensive in nature and progressed to a point where it was affecting the overall load-carrying capacity of the suspended parking slabs. 

Repairs were required to restore the structure’s original load-carrying capacity and reduce further deterioration and to protect the suspended parking slabs against the further ingress of moisture and chlorides. A top-slab replacement repair strategy was selected for this project in lieu of a conventional approach, in which all of the suspended parking slabs would be demolished and replaced with new slabs. 

The top-slab replacement repair strategy option salvaged as much of the existing structure and building systems as possible, extended the service life of the existing structure 
an additional 20 to 25 years, had a lower construction cost, and significantly reduced the environmental footprint of the project. Furthermore, it is important to note that incorporating a top-slab replacement repair strategy did not preclude adapting the design criteria outlined in CSA S413, “Parking Structures,” to improve the long-term durability of the structure. 

The use of state-of-the-art hydrodemolition equipment also permitted the ongoing operation of the building above the parking garage throughout the construction period, which was critical to the success of the project.