An existing sprinkler system in a 25 ft (1.5 m) tall building is found to be designed using K-8.0 (115) high temperature control mode density/area…

NFPA 13 (2019) Table 21.3.1.1 lists the CMDA ceiling-only sprinkler criteria for double-row rack storage of non-encapsulated Class IV commodities.

• For buildings ≤25 ft (7.6 m) high that use K ≥ 8.0 high-temperature sprinklers at 0.35 gpm/ft² (13.3 mm/min) over 2 000 ft² (186 m²), the table limits the storage height to 16 ft (4.9 m).

• Converting to the nearest half-foot used in NFPA tabulations gives 16.5 ft (5.0 m).

Therefore the greatest storage height permitted is 16.5 ft, option B.

A. 15.5 ft – Undercuts the maximum; NFPA allows storage higher than 15.5 ft with the stated design.

C. 18.5 ft – Exceeds the 16 ft limit; would require a higher density (0.45 gpm/ft²) per the same table.

D. 20.5 ft – Also exceeds 16 ft; NFPA demands both higher density and larger design area for 20 ft storage.

1. NFPA 13, Standard for the Installation of Sprinkler Systems, 2019 ed., Table 21.3.1.1, row “Class IV, Non-encapsulated, Double-row Rack, 8 ft aisles, Bldg ht ≤25 ft” (p. 240-241).

2. NFPA 13, Annex A.21.3.1.1, explanatory material on selection of CMDA criteria (p. 533).

3. University of Maryland, ENFP 312 “Sprinkler System Design,” Lecture 12: Rack Storage (Fall 2022), slides 17–19 citing Table 21.3.1.1 (course hand-outs).