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Princess Margaret Hospital, Toronto

A new cancer research facility which retained the 1920's 6 storey stone façade, which converted the original Ontario Hydro office building to accommodate incorporation into the adjoining Ontario Cancer Institute – Princess Margaret Hospital. 

The Ontario Cancer Institute – Princess Margaret Hospital structure was developed as a unique response to the Hospital’s crucial needs. A critical lack of space on the downtown site required a number of architectural and hence structural initiatives to create an integrated solution. The needs of the facility could only be accommodated by the inclusion of an extensive cantilevered section of the hospital 6m (20 ft.) over Murray Street. Special municipal approvals and an innovative structural solution were required for the extremely long cantilevers. Quinn Dressel Associates designed an integrated structural steel/post tensioned deflection control system to maintain the ends of the cantilevers at an acceptable level and to minimize relative floor to floor deflections. 

The Ontario Cancer Institute – Princess Margaret Hospital facility houses specialised diagnostic, research and treatment spaces, laboratories and related equipment. With 13 radiation treatment rooms in the basement area, the wall thicknesses had to be smaller than normal. Wall and slab thicknesses of 2500mm were specified to contain the effects of radiation, requiring specific pouring and curing methods. The required protection was achieved for thinner 1500mm walls without compromise to the shielding capabilities by utilising a custom, high-density concrete mix. Quinn Dressel Associates designed the mix and sourced the aggregate. 

The double height atrium space - framed in structural steel - is an architectural design feature of the building and contains a number of cantilevered interstitial stairs and suspended elevator machine room.

Photos Courtesy of Balthazar Korab K/HB