A Height Limitation for Mercantile with Group A?

In mercantile occupancy, are products classified as Group A Plastics limited to 12-ft, 8-ft, or 5-ft in height when mixed with other Class I-IV products (not segregated)?

If the Group A Plastic products are not mixed with other products (segregated in their own areas), is the storage limited to 12-ft, 8-ft, or 5-ft in height?

Our adopted edition is NFPA 13, 2019.

For context, a mercantile occupancy is shown as Ordinary Hazard Group 2 in NFPA 13, 2019 Section A.4.3.4. NFPA 13, 2019 §3.3.134.5 defines OH2 as "Occupancies or portions of other occupancies where the quantity and combustibility of contents are moderate to high, stockpiles of contents with moderate rates of heat release do not exceed 12 ft (3.7 m), and stockpiles of contents with high rates of heat release do not exceed 8 ft (2.4 m)."

NFPA 13, 2019 §3.3.18 defined low-piled storage as "Solid-piled, palletized, rack storage, bin box, and shelf storage up to 12 ft (3.7 m) in height."

However, in NFPA 13, 2022, this definition was changed to match the requirements of Chapters 4 and 20. NFPA 13, 2022 §3.3.14 defines low-piled storage as "Solid-piled, palletized, rack storage, bin box, and shelf storage of Class I through Class IV commodities up to 12 ft (3.7 m) in height and solid-piled, palletized, rack storage, bin box, and shelf storage of Group A plastic commodities up to 5 ft (1.5 m) in height."

Chapter 4 table 4.3.1.7.1 limits group a plastics in OH2 to 5ft for low-piled storage.

NFPA 13, 2019 §20.4.14.2 states "Unless the requirements of 20.4.13.3 or 20.4.13.4 are met, mixed commodity storage shall be protected by the requirements for the highest classified commodity AND storage arrangement"

​Thanks for your help in clarifying this.

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