Class I is the lowest step in the NFPA 13 storage classification: the product itself is noncombustible, and the only fuel is the wood pallet, single-layer corrugated carton or paper wrapping that carries it.
Quick reference
| Item | Value |
|---|---|
| NFPA 13 class | Class I |
| Product | Noncombustible |
| Permitted packaging | Wood pallet, single-layer corrugated carton, paper wrapping |
| Plastics | Negligible (labels, small trim) |
| FM Global DS 8-1 | Class 1 (definitions not identical) |
| Typical protection | Ceiling sprinklers (CMDA/CMSA/ESFR); in-rack where tall racks require it |
What it is
A Class I commodity is a noncombustible product such as metal, glass, ceramic or stone, stored on wood pallets, in ordinary single-layer corrugated cartons (with or without single-thickness dividers) or in ordinary paper wrapping. Negligible plastic, such as knobs or labels, may be present. The packaging and pallet, not the product, set the fire load, which is why the protection need is the lowest.
Typical examples
- Metal parts and fasteners in cartons
- Glass bottles of noncombustible liquids in single-layer cartons
- Canned food in cartons
- Cement, plaster and other minerals in paper bags
- Metal household goods, unpacked or in light cartons, without significant plastic
How packaging and plastics change the class
The line between Class I and Class II is packaging thickness: put the same glass bottle in a multi-wall carton, a wooden crate or a heavy case and it becomes Class II. Plastics cause a bigger jump: once the Group A plastic content of the product or its packaging passes set thresholds, the commodity moves straight to Class IV, and at higher proportions into the Group A plastics category. Storing on plastic pallets can also raise the class.
Protection approach
For Class I, control mode density/area (CMDA), control mode specific application (CMSA) and ESFR ceiling sprinklers are generally all available. Where ceiling height and obstruction rules are met, ESFR usually removes the need for in-rack sprinklers. Very high storage, or racks with solid shelves, may still need in-rack protection. The design density is read from the storage chapters of the standard according to storage height, rack type and aisle width; we do not quote a single figure here because it changes with those variables.
FM Global equivalent
FM Global DS 8-1 also uses four classes, and Class I broadly corresponds to FM Class 1. The definitions and test basis of the two bodies are not the same, so on an FM-approved project the class should be set separately from the DS 8-1 tables.
The commodity class depends on what goes into the warehouse today. The commodity and storage arrangement assumed in the design report should be recorded in writing and rechecked whenever operations change. For the overall framework see NFPA 13 commodity classification, and for a quick check on whether ESFR can be used, the ESFR suitability checker.
Common site mistakes
- Looking only at the noncombustible product and ignoring pallet and carton.
- Treating stretch wrap and plastic corner guards as negligible; as the amount grows, so does the class.
- Missing a switch from single-layer to multi-wall cartons.
- Not reflecting a change to plastic pallets in the sprinkler design.
- Not re-assessing the class when plastic goods start arriving in the warehouse.
Frequently Asked Questions
Does a metal parts warehouse need sprinklers?
The product is noncombustible, but pallets and cartons burn, so it is protected as a Class I commodity. For entirely unpackaged noncombustible material, the requirement is agreed with the authority having jurisdiction.
Are glass bottles Class I or Class II?
Glass bottles of noncombustible liquid in single-layer cartons are Class I; in multi-wall cartons or wooden crates they are Class II.
Can ESFR be used for Class I?
Yes, provided ceiling height, obstructions and rack layout meet ESFR conditions. The ESFR suitability checker gives a quick first check.
SprinkCalc — Fire Sprinkler Design Across Three Standards
SprinkCalc covers hazard classification, design density and area, K-factor selection, water demand and hydraulic calculations for NFPA 13, FM Global and BS EN 12845 in a single iOS app, and exports a professional PDF report.
Download SprinkCalc on the App StoreNFPA 13, Standard for the Installation of Sprinkler Systems (current edition) · FM Global Property Loss Prevention Data Sheets (FM Global DS 8-1). This page summarises the definitions in our own words; for design densities, areas and height limits the edition in force and the decision of the authority having jurisdiction govern.