The Marvel of Cantilever Balcony Engineering
Each theatre is a marvel of design and engineering. Building a sound structure is only part of the equation. Architects must also factor in the stress on certain areas when the theatre is at capacity, consider optimal sightlines, and craft an aesthetically pleasing building too. Balconies add another level (no pun intended) of complexity to the mix. In order to safely add them support posts were commonly used in their construction, but they could obscure sightlines or crowd exit lanes, as seen in the two photos below.
At the end of the 19th century the concept of cantilever balconies were introduced to theatre construction. A cantilever balcony uses a rigid beam anchored only on one side that eliminates external support such as supporting columns. Thought to have been first introduced in British theatre design, one of the earliest known examples in America is the New Amsterdam Theatre in New York, which opened in 1903.
Architects Rapp & Rapp and the Balaban & Katz chain took the cantilever balcony several steps further with the construction of the Chicago theatre and other movie palaces. The entire capacity of the New Amsterdam auditorium is 1,702 seats, the Chicago theatre held nearly that in its balcony with 1,504 seats. The Chicago has a huge cavernous auditorium that is 7 stories tall with the stage measuring over 60 feet, it was said to be the largest movie palace at the time of its opening in 1921.
Seeing a balcony as large without supports must have been a jarring sight, surely they would collapse under its own weight, to say nothing of when it was full of people. Now they are commonplace, but imagine seeing one for the first time when you were used to columns holding them up. The load capacity of the balconies would have been calculated by the engineers, but how to assuage the public’s concern? One way to test the load capacities is with sandbags. It is speculated that Balaban & Katz saw these sandbag tests as a public relations opportunity and circulated photos of these tests to assure the public that the massive cantilever balconies in their theatres were indeed safe.
The above two photos show sandbag testing from the Chicago Theatre and the Southtown Theatre built by Rapp & Rapp in 1931 for Balaban & Katz.
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