Racks with Wood as Solid-Shelf or Solid-Piled?

5/5/2022

We have an NFPA 13 system with portable stackable racks.

These are 8-ft tall, made of steel tubing and solid wood floors (which carry window and door products).

Should this be considered solid-shelf rack storage, or solid-piled storage?

Thanks in advance.

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11 Comments

Alex

5/5/2022 05:16:08 am

Hi,

I'm on the road this morning so I cant leave any code sections.

I would deem this as solid shelf since you have a solid wood base. Therefore, it isn't only the commodity that is making the pallets 'appear' solid, like you would see for solid-piled storage.

Curious to see what others say. Rack storage is not my area of expertise.

Thanks,
Alex

Pete H

5/5/2022 06:49:34 am

I have to agree with Alex. If it was piles of wood atop a slatted shelf, that would just be the commodity but not the shelf. But it's not. You have a solid wood base in the description. So it is solid shelf racks.

Pete H

5/5/2022 06:51:56 am

Rereading I see the question was whether it's solid shelf racks vs solid piled.

I'd go solid shelf racks. Presumably there will still be some empty space atop a storage commodity before the next shelf of a rack. Even an eighth of an inch. You have solid shelves on racks.

Dan Wilder

5/5/2022 08:02:59 am

Just some thoughts...

If the area is greater than 20 sq. ft. then consider it solid shelving
Check the requirements for Low-Piled Storage due to the height of only 8', luckily the chart includes both shelf & solid-piled as types available.
This may trigger pathing layouts and additional hose valves and some specific aisle requirements

You state "Portable, stackable rack storage" leading me to believe in-rack sprinklers are not feasible (I am working on a similar stackable rack system for tire storage to 20' but no solid bases, only frames) so you may need to look at solid piled storage options vs rack storage.

Does your AHJ require racking storage permits? Typically those have some very helpful call outs as to storage definitions being told to the AHJ and maybe even a design criteria.

Dan Wilder

5/5/2022 10:17:07 am

This is what I am dealing with on my tire storage so I assume this is what you have? I am seeing this much more as these have different requirements on the building code side for installation and easier on the owners for storage configuration changes.

https://www.globalindustrial.com/p/portable-stack-rack-48-w-x-48-d-x-48-h-3?infoParam.campaignId=T9F&gclid=CjwKCAjw682TBhATEiwA9crl39Va-rk3POxYDz6SZvuLyIKHbvD9rcVsuJsboJSg0LA-5XNUKp85SBoC__IQAvD_BwE

and now throw in pallets on these racks in various open & shelf configurations with no ability to provide in-rack sprinklers (we've had an owner or two not happy with that limitation)

https://www.google.com/search?q=portable%20rack%20storage&tbm=isch&tbs=rimg:CdqKlXQKn7yxYfVw2Ard7cV2sgIOCgIIABAAKAE6BAgBEAE&hl=en&sa=X&ved=0CAIQrnZqFwoTCPC9xf7RyPcCFQAAAAAdAAAAABAW&biw=1903&bih=937

Nathan Keller

5/5/2022 01:16:42 pm

Yes, in-rack sprinklers are not an option, because these stackable racks will be moved around with forklifts and stacked two-high. The area of each rack is greater than 20 sq. ft. so it cannot be considered open rack shelving. I will look into the racking storage permits. Thank you!

Jesse

5/5/2022 08:15:18 am

Effectively this is solid shelving, not to be treated as solid unit load pile. The issue will be the air movement between tiers of storage in the event of a fire, which you have in this case but not in the case of a solid pile. This is the same reason a 6-ft stack of idle wooden pallets is treated differently than a 6-ft stack of lumber.

Nathan Keller

5/5/2022 01:17:57 pm

That's a very persuasive argument.

Eric R

5/5/2022 11:30:41 am

Took a few minutes to look through NFPA 13, and all I can offer up at the moment is that you'll definitely want to measure those shelves asap to see if they fall under 20 sqft.

If they are over 20 sqft it looks like they would clearly be defined as solid shelf racks, but solid shelf racks require in-rack sprinklers, and I don't see any exemptions for portable racks. The sole exception I see would be enforcing miscellaneous storage rules for floor area and quantity limitations on the facility which doesn't sound like much fun.

Nathan Keller

5/5/2022 01:25:42 pm

Good observations. Another option I was considering was having my client modify the bottoms of the stackable racks to be slatted rather than solid. 16.2.4.1.2 of NFPA 13, 2016 edition outlines the conditions where this is valid. I ended up not being able to go this route because the building ceiling is too tall and is using ESFR sprinklers.

Bob

5/10/2022 06:15:48 pm

I think when it comes to the actual fire engineering, Jesse's comment most resembles the proper view. What is likely understated above in the “up to 20 SF” comments are some of the NFPA-13 (2019) restrictions. (NOTE: there is another change point above 64 SF).

The 20 SF consideration has been in NFPA-13 for several releases now, but 2019 really double downs on the issue and I’m not aware of any exceptions for “portable racking.”

One of the overriding NFPA-13 aspects is that even if the shelf material is open or even non-existent, IF THE PLACEMENT OF THE LOAD HAS AN AREA >20 SF, you have to view it as solid shelving and this brings in-rack sprinklers into the equation pretty fast. Creating open bottoms or even no bottoms does not change this requirement if the load footprint is > 20 SF.

Once the >20 SF threshold is reached by solid shelf material or load placement, the type of roof level system (CMDA, ESFR) also does not matter (Note: There are some CMSA under mercantile occupancies) nor does the commodity classification of the stored product. For example, you can be storing steel metal studs on steel cantilever racks and it does not change in-rack sprinkler requirements.

Until 2019, there was a slight work-around where you could store unlimited lengths of solid shelf perpendicular to the aisle as long as there was a 6-inch transverse flue every 5’. NFPA-13 (2019) now limits length (to around 16’ or so), but there may be a way to arrange short segments of your stacked “portable rack” with solid shelving or loads >20 SF perpendicular to the aisle creating 6” transverse flues every 5’ that would allow you to address the required density with the roof level system only.

Racks with Wood as Solid-Shelf or Solid-Piled?

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