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Few words meet with as much disdain amongst some on UrbanToronto's Forum as does the term 'spandrel,' a type of cladding most often either made of glass or aluminum, and used as part of a cladding system when a window is not desired. The disdain comes from observers wishing that more traditional opaque wall materials like brick were being employed, often because spandrel more often that not is tinted gray, while bricks more often than not have been of warmer hues, provide more texture, and project more solidity and permanence.
The term 'spandrel' traditionally referred to the space between two architectural areas, such as the triangular piece of wall between an archway and the corner of that wall. More recently, however, 'spandrel' is now more associated with panels, horizontal or vertical, that separate windows, typically employed on new builds in place of more traditional wall materials like brick or stone or more recent ones like precast concrete.
Since many modern Toronto buildings are sealed with a window wall facade — an inexpensive cladding system that can provide large windows — the use of spandrel panels allows for opaque elements to be introduced while maintaining a mostly glass exterior. Spandrel is designed to hide existing building material components such as walls, floor slabs, and ducts for ventilation, HVAC, or cables.
If the spandrel panel is made with glass, typically a ceramic frit or silicone elastomeric paint are applied to its interior side to ensure the glass is opaque, hence a fuller term 'back-painted glass spandrel.' The glass, which must be heat treated, can be colour customized as a decorative or contrasting feature or to match the surrounding window wall, but as mentioned, more often than not in recent years is tinted a shade of gray in Toronto buildings.
Spandrel panels are also often made of aluminum sheets, typically either powder coated for a long-lasting paint-like finish, or anodized when a lustrous metal sheen is desired. In the image above, the recently completed Local at Fort York, built beside the elevated portion of the Gardiner Expressway, both types of spandrel panel can be seen; the gray panels between floors and suites at the centre of the image are back-painted glass, while the rusty-red panels are powder coated aluminum.
Behind either type of spandrel panel, a typical insulated wall with a primed-and-painted drywall surface will be found on the inside, meaning that from within a room, a spandrel exterior is indistinguishable from any other solid wall.
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From 2015 to 2017, UrbanToronto and its sister publication, SkyriseCities, ran an occasional series of articles under the heading Explainer. Each one took a concept from Urban Planning, Architecture, Construction, or other topics that often wind up in our publications, and presented an in depth look at it. It's time to revisit (and update where necessary) those articles for readers who are unfamiliar with them. While you may already know what some of these terms mean, others may be new to you. We are publishing or updating and republishing Explainer on a weekly basis. This article is an update and expansion of one that first appeared in 2015.
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