Challenges of Tall Iconic Building Retrofit

Skin, Bones and Internal Systems



Change happens, for better or for worse, to all living and physical matter. In order to thrive and achieve longevity, we constantly need to adapt to our ever changing environment. For individuals, this means taking actions to reduce and manage physical and mental health risks while achieving positive impacts for our family and community. However regardless of corrective measures throughout one’s life, mortality is a given. For tall iconic buildings, demolition is not an acceptable or practical option given their scale and significance. Facade or component renewal to maintain durable enclosure is necessary to extend the useful life of iconic tall towers.

Further, climate change has been at the center of public and policy discussions, and building energy consumption has been identified as a key contributor to the problem. The key to solving this problem lies in how the building envelope and mechanical / electrical systems perform, preferably not in isolation, but as part of an overall renewal plan. Energy conservation measures through retro-commissioning can make a substantial impact in large buildings. Facade and retro-commissioning work can be carried out as independent project. Tower Renewal Guide (Kesik, and Saleff 2009) and Roadmap for Retrofits (Chisholm 2016) of large buildings have been developed to guide property owners and stakeholders to plan and take the necessary corrective actions.

This paper highlights retrofit of three tall iconic towers in downtown Toronto (Fig. 1) with various degrees of renewal, ranging from spandrel/vision re-glazing to coating finish renewal, coupled with internal system retro-commissioning to complete to over-cladding of the exterior envelope. The business drivers for change ranged from risk management of an aged facade to image renewal to compete with newly built towers in a competitive market. Primary challenges with the retrofits were the required upfront due diligence and the unforeseen conditions, design limitations regarding the character defining facade elements, managing the existing de-construction and re-construction of an occupied building, project scale, and finally public safety as it relates to execution of work in tight/confined downtown area.


Photo of Hamid Vossoughi, P.E., P. Eng.

Hamid Vossoughi, P.E., P. Eng.

Senior Principal

WSP Canada Inc.



Figure 1: 100 King St. prior to and rendering of façade retrofit, 77 King St. W. (right hand side of photo), and 401 Bay St. prior to and rendering of

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Buildings as shelter can be perceived as living structure reacting to environmental and internal loads, resembling human body; façade as skin (hair, nail, teeth, etc.), structure as skeleton, and the

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Case Studies

The importance of the three subject buildings and what makes them iconic is the fact that they are respectively the tallest building in Canada, a modernist design by Mies van

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Conclusion and Future Work

Façade retrofit and outward transformation of building appearance can be visually dramatic. This takes years of planning and preparation, site assessment of the existing conditions, need for managing existing construction

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The author would like to thank and acknowledge the various teams involved in these projects including but not limited to; Brookfield Properties, Cadillac Fairview, Hudson’s Bay Company, Bregman + Hamann Architects, Moed de Armas & Shannon Architects, Highland Associates, Ellis Don Corporation, PCL Constructors Canada Inc., D.F. Pray International, Antamex (Oldcastle Building Envelope), Sota Glazing, Flynn Canada and WSP (Building Sciences, Structures, Energy & Sustainability).

Rights and Permissions

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Canadian Standards Association, CSA S478-95 (R2007) - Guideline on Durability in Buildings

Canadian Standards Association, CSA-Z320-11 (R2016) - Building Commissioning Standard

Chisholm, Eric. “A Roadmap for Retrofits in Canada - Charting the path forward for large building” (accessed October 30, 2016).

DeRose, David and Deveau, Adrien. “Rejuvenating a Landmark: Giving First Canadian Place a Look and New Way of Operating.” Ontario Building Envelope Council, Spring 2013.

Kesik, Ted and Saleff, Ivan. Tower Renewal Guidelines, University of Toronto, 2009.

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