In last week's Explainer, we defined mullions and their practical use as door and window separators. We've also touched on spandrel glass in the past, a common material that is often utilized in residential projects to hide building mechanical components between floors. In this edition of Explainer, we look at the window wall, a cladding system where mullions and spandrel are common. 

Window wall in a Toronto condominium, image by Marcus Mitanis

Window walls are often compared to curtain wall systems, which are generally more expensive. Typically found in office and hotel projects, curtain walls are affixed over the concrete slabs of a building, visually hanging off the skeleton while physically affixed to it with metal plates. Window walls, on the other hand, are installed between the concrete slabs and sealed with caulking.

Window wall in a Toronto condominium, image by Marcus Mitanis

Since window wall glazing is not as physically strong as curtain wall glazing, mullions are typically installed for structural support, and maintenance is required more often. Buildings that implement a window wall system also tend to present a rougher texture, as opposed to the generally smooth surfaces associated with curtain walls. 

Virtually all buildings employ a window wall system in this shot, image by Marcus Mitanis

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