A strong but lightweight exposed floor system with a 2-hour fire rating and new structural steel, allowed for the construction of a newbuilding behind a historically significant brick façade.

When facing a renovation in prime Toronto real estate with tight operating space, a client-mandated strong but lightweight exposed floor system with a 2-hour fire rating, and an aggressive time schedule, you need a solution as unique as the challenges. Such was the situation at 401 Yonge Street in Toronto. The existing building was a 3-storey wood structure with wood demising walls and a historically significant brick façade.

Thus a structure providing lateral support was necessary first to, in effect, build a new building behind the existing façade. Consulting engineers Atkins + Van Groll Inc. of Toronto provided the structural design for the new building and temporary structures, as well as assisting with sound and fire rating requirements. Founding partner Raymond Van Groll, “the client wanted to create new retail space with a ground floor structure capable of supporting 200 PSF that when exposed needed no additional material for fire rating, and with a minimal number of columns. Also a 2nd floor and room structure with the capability of adding a rooftop patio.”

The solution? ComSlab®, a unique decking system combining steel and concrete cured together and bonded structurally as one element. Compared to traditional cast-in-place concrete floors, ComSlab can save up to 40% concrete, 50% steel rebar, and 50% in shoring costs. Being stronger and lighter than other floor systems it allows for shallow floor depths and clear spans.  The previously 3-storey structure became two storeys plus lower level storage space.

Bailey Metal Products Ltd., a customer of ArcelorMittal Dofasco, manufactured and supplied the ComSlab, National Director, Business Development, Tony Di Giovanni says ComSlab’s “maneuverability, light-weight and quickly installed self-positioning interlocking system made it a ‘natural’ for this project”.