FM Global DS 8-1: Mixed Commodity Storage Design

A modern warehouse rarely holds a single commodity: furniture, cartoned electronics and plastic containers often share the same area. FM Global handles this with two data sheets: the commodity is classified under DS 8-1 Commodity Classification (April 2014, interim revision October 2025) and protected under DS 8-9 (March 2010, interim revision April 2026). The basic rule is simple: protection is based on the highest-hazard commodity in the facility.

The Current FM Commodity Ranking

DS 8-1 §2.1 ranks the standard commodities from lowest to highest hazard:

• Noncombustible
• Class 1, Class 2, Class 3
• Class 4 / cartoned unexpanded plastic (CUP)
• Cartoned expanded plastic (CEP)
• Uncartoned unexpanded plastic (UUP)
• Uncartoned expanded plastic (UEP)

The April 2014 revision removed the Group A, B and C plastic categories and the separate Class 4 category; Class 4 commodities are now protected as CUP (DS 8-1 Appendix B). How an individual commodity is classified is covered in the DS 8-1 commodity classification article.

The Highest-Hazard Commodity Rule

• DS 8-1 §2.4.1.1: base protection on the highest-hazard commodity at the facility.
• DS 8-9 §2.2.2.2: base the protection for a storage area on the most severe commodity hazard present anywhere within it.
• DS 8-1 §3.2.1: do not base protection on an average of the commodities.
• There is no percentage threshold for this rule. The 5% limit in DS 8-1 classifies an individual commodity, not a mixed storage area: Class 1–3 materials with no more than 5% plastic remain Class 3 (§2.2.4.1), while more than 5% unexpanded plastic in a single pallet load makes the material unexpanded plastic (§2.2.5.1).

Why Commodities Are Not Averaged

DS 8-1 §3.2.1 gives three reasons:

• In fire tests, replacing one tier of a four-tier rack array with a higher-hazard commodity produced a hazard much higher than a rack filled entirely with the lower-hazard commodity.
• With adequate protection, tests typically burn about 19–28 m² (200–300 ft²) of commodity, yet the sprinkler operating area reaches 140–230 m² (1500–2500 ft²). A more hazardous commodity can enlarge the burning area and overtax a system designed for the lower hazard.
• Averaging requires continual monitoring to make sure the proportion of higher-hazard commodities is not exceeded, which is very difficult and generally not feasible in normal warehouse operations.

The Alternative: Segregating the Highest-Hazard Commodity

• DS 8-1 §2.4.1.2: as an alternative to protecting the whole facility for the highest-hazard commodity, segregate that commodity from the rest of the facility and protect it accordingly.
• The same clause notes that keeping it properly segregated can be very difficult in normal warehouse operations; the arrangement depends on operational discipline.
• Neither DS 8-1 nor DS 8-9 specifies an aisle width or fire wall rating for this segregation. Construction follows the relevant FM construction data sheets (DS 8-9 §2.1.1.1).

Small Quantities of a High-Challenge Commodity: Scheme 8-9A

Where the most severe commodity is present in relatively small amounts throughout the storage area and protecting it is a challenge, DS 8-9 §2.2.2.3 points to Scheme 8-9A (§2.3.4.9, Appendix A):

• The high-challenge commodity is kept in a dedicated rack (or racks). If the rack is not solely dedicated to it, extend the protection one pallet load in all directions or install a vertical barrier (§2.3.4.9.1).
• Horizontal barriers are installed, with minimum K8.0 (K115) FM Approved quick-response in-rack sprinklers fed only by a wet system beneath each barrier (§2.3.4.9.2–§2.3.4.9.3).
• The in-rack system is designed for at least 230 L/min (60 gpm) from the most remote 6 sprinklers in single-row racks or 8 sprinklers in double- and multiple-row racks, plus a 950 L/min (250 gpm) hose allowance, for at least one hour (§2.3.4.9.3).
• The ceiling system is designed for the highest commodity hazard not protected by Scheme 8-9A (§2.3.4.9.4); the in-rack demand does not have to be hydraulically balanced with the ceiling system.

Adjacent Areas: Extending the Hydraulic Design

Under DS 8-9 §2.3.3.5, where two adjacent storage occupancies are protected differently, the design for the higher-hazard one is extended one branch line or one sprinkler into the lower-hazard area. Where there is mixed-use occupancy, the storage design is extended at least one branch line or sprinkler beyond all edges of the storage, or to a wall.

Decision Sequence

1. List all commodities and classify them under DS 8-1 (material and internal packaging, external packaging, pallet).
2. Identify the highest-hazard commodity in the storage area.
3. Check whether protecting the whole area for that commodity under DS 8-9 is feasible in terms of water supply and cost.
4. If not, consider segregation (DS 8-1 §2.4.1.2) or Scheme 8-9A (DS 8-9 §2.3.4.9).
5. Extend the hydraulic design between differently protected adjacent areas per DS 8-9 §2.3.3.5.

Quick Checklist

• All commodities listed and classified using the current FM categories (Class 1–3, CUP, CEP, UUP, UEP)
• Protection based on the highest-hazard commodity present, not on an average
• If segregation is used, how it will be maintained in operation is documented
• If Scheme 8-9A is used, the dedicated rack, horizontal barrier and in-rack sprinkler conditions are met
• Hydraulic design extended between differently protected adjacent areas

Frequently Asked Questions

What happens if the warehouse holds only a small amount of plastic?

Under FM DS 8-1 §3.2.1 and DS 8-9 §2.2.2.2, protection is based on the most severe commodity hazard present anywhere in the storage area; commodities are not averaged. If the high-hazard commodity is present in small amounts and is difficult to protect, DS 8-9 §2.3.4.9 allows it to be segregated into a dedicated rack protected by Scheme 8-9A.

Does the 5% plastic limit apply to mixed storage?

No. The 5% limit classifies an individual commodity: under DS 8-1 §2.2.4.1, Class 1–3 materials containing no more than 5% plastic by weight or volume remain Class 3, and under §2.2.5.1 more than 5% unexpanded plastic in a single pallet load makes the material unexpanded plastic (UP). There is no percentage threshold for the proportion of different commodities in a warehouse.

Are Group A plastics and Class 4 still used?

Not by FM. The April 2014 revision of DS 8-1 removed the Group A, B and C plastic categories and Class 4 (Appendix B). Plastics are now classified as unexpanded or expanded, and as cartoned or uncartoned: CUP, CEP, UUP and UEP. Class 4 commodities are protected as CUP.

Can different commodities be separated by an aisle or a fire wall?

DS 8-1 §2.4.1.2 accepts, as an alternative to protecting the whole facility for the highest-hazard commodity, segregating that commodity from the rest of the facility and protecting it accordingly, but notes that keeping it properly segregated is very difficult in normal warehouse operations. Neither DS 8-1 nor DS 8-9 specifies an aisle width or fire wall rating for this; construction follows the relevant FM construction data sheets (DS 8-9 §2.1.1.1).

How is the design handled where two differently protected storage areas are adjacent?

Under DS 8-9 §2.3.3.5, where two adjacent storage occupancies are protected differently, the design for the higher-hazard area is extended one branch line or one sprinkler into the lower-hazard area.

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