EN 12845 Annex G.5: Sprinkler Protection of Idle Pallet Storage

Source: TS EN 12845+A2:2026, Clause G.5 "Idle pallets" and Table G.5 (EN p.149), Table G.6 (EN p.150). This article rests solely on those clauses and on Table 4 (EN p.38) and Clause 5.2 (EN p.30) to which they refer.

Idle pallets are one of the most demanding items in a warehouse in terms of fire load; the standard deals with them as a separate clause within Annex G. The body of Clause G.5 is short and refers to two tables: Table G.5 for storage in solid piles or on pallets, and Table G.6 for rack storage.

The text of Clause G.5

Clause G.5 (EN p.149): "Idle pallets stored in solid piles or on pallets shall be protected with ceiling sprinklers in accordance with Table G.5. Pallets stored in racks shall be protected with ceiling and in-rack sprinklers in accordance with Table G.6."

Table G.5: Protection of idle pallets (ST1)

ST1, in accordance with Clause 6.3.2 (EN p.33), is the free-standing or block stacking configuration.

Source: Table G.5, EN p.149.

The difference between the two rows matters. For wood/cellulose pallets the table gives no fixed density, it refers directly to the Category IV column of Table 4. For plastic pallets, by contrast, it gives a fixed design independent of Table 4 (25 mm/min x 300 m2) together with a structural requirement (60 min compartment).

Wood pallets: the Category IV column of Table 4

Table 4 (EN p.38) is for HHS storage with roof or ceiling protection only. In the ST1 (free-standing or block stacking) row group, the maximum permitted storage heights for Category IV and the corresponding design criteria are as follows:

Source: Table 4, ST1 row group, EN p.38.

Since Table G.5 limits the maximum height for wood pallets to 3.8 m, the design at that limit is the ST1/Category IV 3.8 m row of Table 4: 25 mm/min, 300 m2. For lower stacks the lower rows of the table are used.

The NOTE to Table 4 (EN p.38): on high hazard storage, dry and alternate systems should be avoided, especially with the more combustible products and the higher storage; should it nonetheless be necessary to install a dry or alternate system, the area of operation should be increased by 25%.

Table G.6: Protection of rack storage of pallets (ST4, ST5, ST6)

Source: Table G.6, EN p.150.

The hydraulic assumption for in-rack sprinklers is in Clause 7.2.3.3 (EN p.37): on each level the 3 most hydraulically remote sprinklers operate simultaneously, up to a maximum of three levels. Where the aisle is 2.4 m or more in width one rack is taken to be involved, where it is between 1.2 m and 2.4 m two racks, and where it is less than 1.2 m three racks. Under Clause 7.2.3.1, where there are more than 50 in-rack sprinklers they cannot be fed from the same control valve set as the ceiling sprinklers; under Clause 7.2.3.4, in-rack sprinklers and the associated ceiling sprinklers are always fully calculated and the minimum pressure at any operating sprinkler is 2.0 bar (Clause 13.4.4).

Pallet storage in the open air

Clause 5.2 (EN p.30): the distance between combustible material stored in the open air and the sprinklered building shall correspond to the regulatory provisions in the place of use. Where it is not regulated, this distance shall be no less than 10 m or 1.5 times the height of the stored material. NOTE: such a fire resistant separation can also be achieved by a firewall or by a suitable exposure protection system.

The standard gives no other numerical criterion for open air pallet stacks, such as distance to the facade, eaves distance, footprint area, stack height or distance to a hydrant.

Block area and aisle limits

Table 2 (EN p.34) gives, for the ST1 configuration in the high hazard class, a maximum storage block area of 150 m2 and a minimum separation clearance around the storage block of 2.4 m. For ST4 in high hazard, where there is no intermediate level in-rack sprinkler protection, the block area is unlimited and the aisle width has to be 1.2 m or greater.

What the standard does not say here

• Other stack height limits such as 1.8 m or 1.2 m. The limits Table G.5 gives are 3.8 m (wood/cellulose) and 3.3 m (plastic).
• An ESFR design, a K-factor or a sprinkler count for idle pallets. There is no ESFR in Clause G.5 or in Tables G.5/G.6.
• A distinction such as "close-piled / spaced piling" and a different height limit tied to it.
• Distances such as 6 m, 8 m, 9 m or 12 m for open air stacking. The only numerical rule is in Clause 5.2.

Field note

Field note (not from the standard, this is engineering commentary): the idle pallet stock is the fastest growing and least supervised load during operation; where the project design is based on a particular type of pallet, a change of pallet type in service (in particular a move from wood to plastic) invalidates the design. For that reason, which row of Table G.5/G.6 has been taken as the basis should be visible in the project information held in the control valve room.

Frequently Asked Questions

To what height may idle wood pallets be stacked?

TS EN 12845+A2:2026 Table G.5 (EN p.149): for wood and cellulose material pallets the maximum permitted storage height is 3.8 m and the ceiling sprinklers are designed as for Category IV in accordance with Table 4. In Table 4 the ST1 Category IV row for 3.8 m gives 25 mm/min and 300 m2.

What is the design criterion for plastic idle pallets?

Table G.5 (EN p.149): for plastic pallets the maximum storage height is 3.3 m, the ceiling sprinklers are 25 mm/min over 300 m2, and as a special requirement storage is in a 60 min fire resistant compartment.

How is idle pallet storage in racks protected?

Table G.6 (EN p.150) covers ST4/ST5/ST6 rack storage. For wood and cellulose pallets and for non-expanded high density polyethylene pallets with a solid deck, the in-rack sprinklers are Category IV, the ceiling sprinklers are as per Category IV in accordance with Table 4 and are rated at 93 C or 100 C; for storage above 3.8 m a 60 min fire resistant compartment is required. For all other plastic pallets the in-rack sprinklers are Category IV plus one level above the top level of storage, with K = 115 and a minimum operating pressure of 3 bar; the ceiling is 25 mm/min over 300 m2 with a 60 min compartment.

How close to a building may a pallet stack in the open air be?

Clause 5.2 (EN p.30): the distance between combustible material stored in the open air and the sprinklered building corresponds to the regulatory provisions in the place of use. Where it is not regulated, this distance shall be no less than 10 m or 1.5 times the height of the stored material.

Can ESFR be used for idle pallets?

There is no reference to ESFR in Clause G.5 or in Tables G.5/G.6. For ESFR systems, Annex P of TS EN 12845+A2:2026 (normative, EN p.164) requires EN 12845-2 to be applied; an ESFR design for idle pallets is dealt with by that route and not through Annex G.

References

• TS EN 12845+A2:2026 Clause G.5 and Table G.5 (EN p.149)
• TS EN 12845+A2:2026 Table G.6 (EN p.150)
• TS EN 12845+A2:2026 Table 4 and NOTE (EN p.38)
• TS EN 12845+A2:2026 Table 2 (EN p.34)
• TS EN 12845+A2:2026 Clause 6.3.2 (EN p.33)
• TS EN 12845+A2:2026 Clause 5.2 and NOTE (EN p.30)
• TS EN 12845+A2:2026 Clauses 7.2.3.1, 7.2.3.3, 7.2.3.4 (EN p.37)
• TS EN 12845+A2:2026 Annex P (EN p.164)

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