I was looking for some technical assistance from others who are familiar with NFPA 13 sprinkler requirements for storage over 25 ft. According to the code, there seems to be a conflicting definitions of Single-Row, Double-Row, Multi-Row, and Back-to-Back racking. What I am most concerened with is the longitudinal flue requirements for single-row and double-row racking according to 16.1.11.1:

"Nominal 6 in transverse flue spaces between loads and at rack uprights shall be maintained in single-row, double-row, and multiple-row racks. Nominal 6 in longitudinal flue spaces shall be provided in double-row racks. Random variations in the width of the flue spaces or in the vertical alignmnets shall be permitted."

This implies that the longitudinal flue is not required with multi-row racking, what is presssumed to be a greater fire hazard...Also multi-row racking definition (3.9.3.7.3) it states that "racks greater than 12 ft in depth or single- or double-row racks separated by aisles less than 3.5ft wide having an overall width greater than 12 ft." Therefore, would a single-rack pushed back-to-back to double-rack require any longitudinal flues?