Class II is a commodity whose product is still noncombustible but which carries more combustible packaging. The difference lies not in the product but in the box or crate around it.
Quick reference
| Item | Value |
|---|---|
| NFPA 13 class | Class II |
| Product | Noncombustible |
| Packaging | Wooden crate/box, multi-wall carton or equivalent |
| Plastics | Negligible |
| FM Global DS 8-1 | Class 2 (definitions not identical) |
| Typical protection | Ceiling sprinklers (CMDA/CMSA/ESFR); in-rack for tall storage |
What it is
A Class II commodity is a Class I-type noncombustible product stored in slatted wooden crates, solid wooden boxes, multi-wall corrugated cartons or an equivalent amount of combustible packaging, with or without pallets. Because the mass of combustible packaging is greater, the fire grows faster and reaches a higher heat release than Class I.
Typical examples
- Ceramics, porcelain or glassware in wooden crates
- Metal machine parts in multi-wall cartons
- Bottles of noncombustible liquid in heavy cartons
- Stone or cast products in wooden cases
- Metal appliances with little plastic in heavy cartons
How packaging and plastics change the class
The lower bound of Class II is Class I: reduce the packaging to a single-layer carton and the commodity may drop to Class I. Upwards there are two routes. If the product itself becomes combustible (wood, paper, natural fibre), the commodity becomes Class III. If the Group A plastic content of product or packaging rises, or Group B plastics appear, it moves to Class IV. Foam packing, blister packs and plastic cases are the most common class-raisers.
Protection approach
The protection approach mirrors Class I: CMDA, CMSA or ESFR ceiling sprinklers, with in-rack sprinklers where storage height and rack layout require them. For the same storage height, Class II needs a somewhat higher density than Class I. In mixed storage where Class I and Class II share an area, the design is normally based on Class II. Values come from the storage tables of the standard according to storage height, rack type and aisle width.
FM Global equivalent
In FM Global DS 8-1 the equivalent is mostly Class 2. FM gives its own packaging and product examples, and borderline cases can be classed differently by FM and NFPA. See DS 8-1 commodity classification for more.
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
- Missing the extra fuel from wooden crates and designing to Class I.
- Ignoring foam or plastic packing inside the crate.
- Overlooking the amount of stretch wrap on the pallet and plastic covers on the product.
- Not updating the class when a supplier changes packaging.
- Not noticing that empty wooden crates are stacked separately in the warehouse, creating a separate hazard.
Frequently Asked Questions
What is the key difference between Class I and Class II?
The product is noncombustible in both. Class I uses single-layer cartons or paper wrapping; Class II uses more combustible packaging such as wooden crates, boxes or multi-wall cartons.
What happens if plastic parts are stored in wooden crates?
The product is a combustible plastic, so the commodity is assessed as Class IV or Group A plastic depending on plastic type and proportion.
Are in-rack sprinklers mandatory for Class II?
Not always. Storage height, rack type and the chosen ceiling sprinklers decide; with ESFR, in-rack protection is often unnecessary.
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.