Group A is the NFPA 13 plastics group with the highest heat release. In storage design two questions decide almost everything: is the plastic expanded (foam), and is it cartoned or exposed?
Quick reference
| Item | Value |
|---|---|
| Unexpanded – cartoned | Lightest Group A case; the carton delays fire reaching the plastic |
| Unexpanded – exposed | More severe; the plastic surface burns directly |
| Expanded – cartoned | Severe; foam burns fast with high heat release |
| Expanded – exposed | Most severe Group A case; some protection options are not permitted |
| FM Global equivalent | CUP / UUP / CEP / UEP categories (DS 8-1, DS 8-9) |
What it is
Group A plastics are polymers that release a high amount of heat when burning. A commodity is classed as a Group A plastic when the Group A content of product or packaging exceeds 15% by weight or 25% by volume. The standard splits the group into unexpanded (solid) and expanded (cellular, foamed) plastics, each of which may be cartoned or exposed. Exposed means unpackaged or packed only in plastic; cartoned means the plastic sits inside corrugated cartons.
Typical examples
- Polyethylene (PE) and polypropylene (PP) containers, crates and toys
- Polystyrene (PS) products; expanded polystyrene (EPS) foam packaging
- ABS and polycarbonate housings
- Empty PET bottles, polyester products
- Polyurethane foam mattresses and upholstery (expanded)
- Synthetic rubbers such as SBR and EPDM
- Highly plasticised flexible PVC
How packaging and plastics change the class
The entry point to Group A is the proportion threshold; below it, the commodity stays at Class IV. Within Group A the split is made by packaging and physical form. A carton helps because water wets it and it delays fire reaching the plastic; torn cartons, open tops or a switch to plastic totes move the commodity into the ‘exposed’ category. Foam plastic burns much faster than solid plastic because of its high surface area and low density. Free-flowing Group A plastics (pellets, powder) are the exception and count as Class IV.
Protection approach
Group A plastics fall under storage criteria even at modest heights; NFPA 13 generally brings Group A storage above 5 ft (1.5 m) into the storage chapters (confirm the threshold in the edition in force). For cartoned unexpanded plastics ESFR is a common and effective solution. For exposed and expanded plastics the options narrow: some ESFR and CMSA combinations are not permitted, in-rack sprinklers are often needed, and open-top plastic containers create their own problem. Design values come from the standard's tables for the commodity sub-category, storage and ceiling height and rack type.
FM Global equivalent
FM Global makes the same split with its own abbreviations: cartoned unexpanded (CUP), uncartoned unexpanded (UUP), cartoned expanded (CEP) and uncartoned expanded (UEP). Protection criteria sit under DS 8-9 plastic storage.
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
- Designing a toy, cosmetics or e-commerce warehouse to Class IV.
- Missing that cartons have been removed over time and goods now sit exposed on racks.
- Treating foam packaging as ‘light and unimportant’ and not checking its volume share.
- Treating open-top plastic totes like cartoned goods.
- Assuming ESFR is valid for every Group A sub-category.
Frequently Asked Questions
What do expanded and unexpanded plastics mean?
Unexpanded plastic is a solid mass (buckets, crates, bottles). Expanded plastic has a cellular foam structure (EPS, polyurethane foam); it burns faster and is harder to protect.
Why is plastic in cartons easier to protect?
The carton delays fire reaching the plastic in the early stage and holds sprinkler water. Cartoned plastics can therefore be met with lower protection criteria than exposed plastics.
Which plastics group is PVC in?
Highly plasticised flexible PVC is Group A; rigid or low-plasticiser PVC is Group C.
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 / 8-9). 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.