Store Group A Plastics Underneath Class I-IV?

12/31/2024

Under NFPA 13, 2016, Miscellaneous and Low-Piled Storage in Table 13.2.1. A system designed for Ordinary Hazard Group 2 allows for 5-ft or less storage of Group A plastics, and in a separate section of the table allows for Class I- IV with a height of 12' or less.

Is it permissible to store the Group A on the floor up to 5-ft in height, with the Class I-IV above it on the racks provided the racks meet the requirements of this section?

Section 5.6.1.2 on Mixed Commodities seems to address more the amount of what is being stored and not so much the arrangement. I can see both side of the argument, but I can't seem to find anything the answers my question definitively.

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4 Comments

Pete H

12/31/2024 06:44:11 am

Some AHJ's allow it, but they probably shouldn't. The testing for low piled and miscellaneous storage is done with these heights as singular commodities and it was found that storing group a plastics under a class 3 commodity still required group a protection.

See NK's posts here:

https://www.meyerfire.com/daily/store-exposed-group-a-in-lowest-rack-only

A point he made I particularly liked is that 5.6.1.2 reads:

5.6.1.2.2 Unless the requirements of 5.6.1.2.3 and 5.6.1.2.4 are met, mixed commodity storage shall be protected by the requirements for the highest classified commodity and storage arrangement."

When you mix em, it becomes group A plastics (the highest classified commodity) and the storage arrangement (the 12'-0" of storage).

Taylor Schumacher

12/31/2024 09:03:47 am

Take a look at 20.4.13 (NFPA 13 2022) for guidance on mixed commodities.

Jesse

12/31/2024 11:32:46 am

That becomes a mixed commodity. Effectively, its all treated as Group-A ~Plastics.

The overriding issue being: even if you could find a loop hole, the likelihood of an OH2 design AS system controlling a fire with that amount of BTU release is about as Dallas winning a Superbowl

Jose Figueroa

12/31/2024 12:04:52 pm

Section 5.6.1.2 on Mixed Commodities highlights the need for careful consideration when storing different classes together.

The short answer is YES as long as:

1. Design is usually based on the most stringent commodity classification and storage height.

2. Stacking order is not specified.But this requires careful storage management.

Recommendations:

- Rack and shelving systems must comply with NFPA requirements for structural and fire protection. Ensure the rack aisles are neat, no storage allowed.

- The fire protection design should focus on the most hazardous commodity, such as Group A plastics.

- Ensure the water supply, sprinkler type, and placement address the worst-case fire scenario.

Local guidance and approval can be obtained from the FD or AHJ.

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Store Group A Plastics Underneath Class I-IV?

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