Solid Shelves if Multiple Skids Less than 20-sqft?

7/26/2021

I'm working with a warehouse owner who has equipment that is on skids, stored onto racks. Each skid is less than 20 square-feet in plan view. This warehouse is only using single-row racks, not particularly high.

I understand 20 sqft to be the maximum threshold for an "open-rack" storage arrangement versus "solid shelves", by the definition of NFPA 13 for solid shelving.

If we maintain flue spaces all around of 6-inches, could the owner theoretically just store each skid at least 6-inches apart, and still not have solid shelf situation?

My gut says that 100-ft long, single row of racks with only this equipment on skids would act more like solid shelves, but if the flues are maintained, then it appears as if NFPA 13 still allows treatment like an open rack. This specific project may be more of a theoretical as the owner has plenty of floor space to limit the overall height of the racks, but I'd appreciate any feedback for future scenarios that come up like this.

Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

5 Comments

Franck

7/26/2021 11:03:51 am

If you have flue spaces, then it is an open rack storage.

The openings are required around the pallet loads. When you have open shelves, as long as tour pallet load is not greater than 20 sq ft footprint, this is fine as you will maintain both the longitudinal and transversal flue.

The purpose is to have a vertical spray of the fire (to quickly activate the ceiling sprinklers (and eventually the in-racks) and a relatively slow lateral fire spread. Solid shelves will limit the vertical spread and accelerate the longitudinal spread by blocking the transversal flues.
Transbversal flues are always mandatory.
Longitudinal flues are recommended (mandatory only for rack storage above 7.6 m).

Your configuration is not different from a storage of a wooden case on a pallet. Same footprint. So as long as it does not exceed 20 sq ft, there is no issue.

The only difference may come from the construction matreial of your skid. If it is made of plastic, then you need to increase the commodity classification (as plastic pallets do).

Jay Richardson

7/26/2021 11:04:33 am

You are correct.
See 2019 NFPA 13: 20.5.3.1 for solid shelving.
Also see 2019 NFPA 13: 20.5.3.3.2 for the 6in transverse flue space required between all loads and at rack uprights.

Robert Anderson

7/26/2021 11:48:55 am

If I’m understand your description correctly, the storage arrangement you are describing is basically a single row open rack with standard (≤20 sf) pallet positions. This is the “base concept” for rack pallet storage depicted in NFPA-13.

Your question appears to be whether or not this needs to be viewed as a “solid shelf” condition being created by load placement. To me it is not a solid shelf condition if you have 6” flue space on all 4 sides of a pallet that is ≤ 20 sf.

This issue of load placement creating a “solid shelf” is not new in NFPA-13 (2019); however, this edition is very upfront on stating that – loads with a footprint >20 sf, even if placed on open racks, create a “Solid Shelf” condition! Below is some insight on how to view this.

I would direct your fire engineer or sprinkler contractor to the following NFPA-13 sections:
• Under Definitions-
o 3.3.172 Rack Shelf Area- and note the “. . . required flue spaces.” wording.
o 3.3.199* Solid Shelving- and again note the “. . . by placement of loads” and “. . . required flue spaces.” wording. Then note Annex A info-
 A.3.3.199 Solid Shelving- makes it clear that the 6” space is required on all 4 sides; note the “all 4 sides” requirement, but then also calls out 20.5.3.1.2 for “additional allowance for double-row racks up 25’ . . .”
• 20.5.3.1.1 allows for no longitudinal flue required up 25’ as long as a 6” transverse flue exists at maximum 5’ intervals. This provision brings the new wording back around to the prior standard pallets (≤20 sf) on double row racks which is in 20.5.3.3.1 Longitudinal Flue Space.

Taking this issue a little deeper, it is worth noting that the solid shelf created by load placement condition is not dependent on the commodity class or roof deck sprinkler type nor open rack or even bare racking. NOTE: There may be some special conditions related specifically to mercantile occupancies, but we mainly deal with warehousing.

It is also worth noting that in multiple-row racks which did not necessarily previously have a “depth limit” as long as the transverse flue was maintained at 5’ oc max – are now limited under Table 25.2.3.2.2.2. This is not clear if you only read about multi-row racks in Chapter 20.

This "solid shelf" issue is a major problem for many operations. We would appreciate a broader discussion of this issue if anyone has additional insight or wants to correct or expand anything stated above.

Jay Richardson link

7/26/2021 07:31:46 pm

For additional discussion...
NFPA 13 requirements for solid shelf racks in low-piled and miscellaneous storage, it appears that solid shelf racks in miscellaneous storage do not require in-rack sprinklers, while solid shelf racks in low-piled storage do.
Do you agree?

12/13/2023 08:16:54 am

Interested if solid shelf racks in miscellaneous storage require in rack sprinklers or are they optional?

Solid Shelves if Multiple Skids Less than 20-sqft?

Leave a Reply.

ALL-ACCESS

SUBSCRIBE

COMMUNITY

YOUR POST

PE EXAM

FILTERS

ARCHIVES

PE PREP SERIES