Cloud ceiling: a suspended ceiling that covers only a portion of a room or space below
These cloud ceilings present unique challenges to fire sprinkler installation. The solution to these challenges are not always easily found clearly in the pages of NFPA 13. However, by applying the obstruction and clearance principles the solution will make itself clear.
• Sprinklers are to be located within 12 inches of ceiling
• 18 inch clearance is to be maintained below the sprinkler head and vertically to.
Typically, cloud ceilings will be greater than 12 inches below the ceiling, requiring sprinkler protection above. Usually, the size of these create an obstruction preventing the spray pattern from reaching the floor, thus requiring sprinkler protection beneath.
Sprinkler protection below may be omitted if the cloud is less than 4’ wide, and configured in such a way that spray pattern obstructions are not created. Sprinkler protection above the cloud may be omitted if the sprinkler deflector below the cloud is within 12 inches of the main ceiling.
For more information check out the article in the July/August 2012 edition of the NFPA Journal, I Really Do Know Clouds, by Matt Klaus.