In section 12 of NFPA 13 (here is the statement that needs to cleared by NFPA)
Ceiling Slope. The sprinkler system criteria specified
in Chapter 12 and Chapters 14 through 20 are intended to
apply to buildings with ceiling slopes not exceeding 2 in 12
(16.7 percent) unless modified by a specific section in Chapter
12 and Chapters 14 through 20.
The issue here is that in chapter 12 and 14 through 20 there are no statement or modifications when ceiling slope exceed 16.7 percent. The problem is that NFPA never address the issue in those chapters if the slope is higher than 16.7%. What will be the criteria if the slope of ceiling exceed in storgae area?
Hope NFPA can address this issue, maybe they overlooked this for years