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Ceiling Pocket vs. Beam Pockets in 13-D

Question asked by lbeaver on Mar 19, 2019
Latest reply on Mar 19, 2019 by lbeaver

Got an easy one for you.

We have a question regarding the 2013 edition of NFPA 13-D and the need for clarification between section 8.3.7 that has the fire protection requirements for “Ceiling Pockets” and section 10.2 that provides installation criteria for sprinklers on the face of  beams in small rooms.  As stated in the requirements of 8.3.7, “Sprinklers shall not be required for ceiling pockets that meet the following conditions:  (1), “The total volume of all unprotected ceiling pockets in a compartment does not exceed 100 ft.3 (cubic feet)”.  An example of this is a room (compartment) that is 10’ x 10’ with a 1’ beam in the middle gives you roughly 100 cubic feet of ceiling pockets.    In the allowances listed in 10.2.1 (2) and (4) is the maximum compartment surface area of 600 ft.2,(square feet).  Is it to be interpreted that using the 100 cubic foot rule of 8.3.7, you can place fire sprinkle at the beam face, not the ceiling pocket in a compartment area of 600 square feet  with beams (architectural surface projections) no greater than 2”.  To follow the math 60’ x 10’ x .166(2”) =99.96 ft.3 or cubic feet, less than the 100 allowed by the code.  You could apply this to a room (compartment) 40’ x 10’ x .25’= 100 ft3 or 20’ x 10’ x .5’=100 ft3.  Is it the intent for the code to be interpreted this way?   Or as the designers in the area believe, that section 10.2.1 allows 14” beam face sprinkler installation in a 600 sq. compartment to create 700 cubic feet of unprotected beam pockets.  Is this the intent of the code?  I do not see a definition for “Beam Pocket” in the 13-D or in 13, however the definition of ceiling pockets is in NFPA 13.  The definition appears to address both ceiling and beam pockets, and it would appear these areas would require fire protection when you reach the defined volume of 8.3.7.