Cloud ceilings are ceiling panels that sit beneath the structural ceiling of a room or space and are seen increasingly in commercial and industrial buildings. “Cloud” panels range in area from discrete ceiling panels with large spaces in between, to close-to-full-room-area contiguous coverage with small gaps at the perimeter wall location.
NFPA 13, Standard for the Installation of Sprinkler Systems, does not have definitive guidance on automatic sprinkler installation requirements for these ceilings and in some conditions requires sprinklers at both the structural ceiling cloud ceiling panel elevations. Recently a set of code changes were proposed to allow only below cloud sprinklers when the gaps between the clouds were small. Small in the context was suggested as an 8 inch or smaller gap based on the modeling performed using Fire Dynamics Simulator (FDS). The proposal was rejected based on the lack of validation for the modeling status.
The Fire Protection Research Foundation initiated this project to obtain an understanding of how cloud ceiling panels impact sprinkler actuation thresholds with an overall goal to provide the technical basis for sprinkler installation requirements. The focus of this project was developing guidance for sprinkler installation requirements for large, contiguous clouds by determining the maximum gap size between the wall and cloud edge at which ceiling sprinklers are not effective. The Research Foundation expresses gratitude to the report authors Jason Floyd, PH.D., and Joshua Dinaburg, who are with JENSEN HUGHES, Inc., located in Baltimore, Maryland.