Portable Orchestra Enclosures and Sprinkler Protection

By John Swanson posted Apr 07, 2022 04:36 PM

  

Portable Orchestra Enclosures and Sprinkler Protection

Fires in theaters, or more specifically, stages inside theaters, have been a fire problem for hundreds of years. The combination of combustible materials, sources of ignition and lots of people has been a fire safety issue spanning modern time. While the installation of automatic sprinkler systems has saved countless lives and reduced the severity of fires that are happening, unfortunately, the number of fires occurring in assembly occupancies is still too high. To complicate things, architects are constantly introducing new construction features requiring the sprinkler industry to reevaluate protection criteria for a space with high fuel loads and combustible materials with elevated heat release rates.

Portable orchestra enclosures

The use of portable orchestra enclosures on stages is a common architectural feature used by many design professionals. Portable orchestra enclosures are acoustic shells that hang from the ceiling of a stage and rotate between the vertical position when stored and the horizontal position when lowered (or in use). When stored in the vertical position near the ceiling, the individual tiles do not present an obstruction to the sprinklers because they are only a few inches thick. When the individual tiles are lowered, they create a “shell”, or an enclosure on the stage. The purpose of the enclosure is to project the sound being performed on the stage out towards the audience. By the push of a button, staff can raise and lower the acoustic tiles for concerts and quickly relocate them back to the ceiling when the performance ends. This saves time for staff and eliminates the need to find storage space in the building for other types of portable orchestra enclosures placed directly on the stage.



Portable or fixed obstruction?

From a fire sprinkler standpoint, the acoustic tiles that make up the portable orchestra enclosure when lowered create a continuous obstruction to the sprinklers at the ceiling that exceed 4 ft in width. The 2022 Edition of NFPA 13, Section 9.5.5.2.1 requires sprinklers “under fixed obstructions over 4 ft. in width”. But is this a “fixed” obstruction? The term “portable” orchestra enclosure appears to answer that question. Unfortunately, it’s not that simple. What if staff forget to raise the acoustic tiles back to the vertical position after a performance? The codes are silent on at what point a portable fixture becomes a fixed obstruction if kept in the same location for weeks or months. The authority having jurisdiction should be aware of the installation of portable orchestra enclosures on stages since the individual tiles can become fixed in the horizontal position for an extended period.



Sprinklers in portable orchestra enclosures

Authorities having jurisdiction and insurance companies, for example, may require sprinklers within these portable orchestra enclosures because they exceed 4 ft in width. However, installing sprinklers within the individual tiles presents new challenges:

  1. If sprinklers are installed to provide coverage within the orchestra enclosure, the individual tiles can no longer be raised back to the stored position at the ceiling, and
  2. With the portable orchestra enclosure in place, it limits the use and size of the stage to the area within the orchestra enclosure. This can be problematic for plays and other theatrical performances that may need the entire area of the stage for scenery, props, etc. but can’t, because the orchestra enclosure limits the size.

Due to the installation of these portable orchestra enclosures becoming more common, the International Building Code (IBC) addressed this issue a few years ago in Section 410. The IBC specifically exempts sprinkler protection within portable orchestra enclosures on stages in Section 410.6. Exception #3 of Section 410.6 says, “Sprinklers are not required within portable orchestra enclosures on stages”.

What does this mean for authorities having jurisdiction?

For authorities having jurisdiction who may be reading this, you may be wondering how to implement procedures to ensure the portable orchestra enclosure does not turn into a “fixed” obstruction. The codes are silent on this issue, and it is ultimately up to you as the authority having jurisdiction. But the fact remains, this issue presents practical difficulties for the AHJ since they cannot be waiting after every performance to ensure staff relocate the tiles back to the ceiling. One possible option is to implement a policy giving staff a specified amount of time after performances to relocate the acoustic tiles back to the ceiling. Ultimately, the final determination on how to enforce this provision of the code is up to the local AHJ.

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