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  • Jerry Schultz, P.E.

Solid Shelving

And so it begins. In my first blog post (Fire Testing, January 18, 2016), I talked briefly about solid shelving and pointed out that there were no new tests introduced to the NFPA 13 committee justifying the change that took place in 1999. It is now 17 years and five editions after the first solid shelving requirements appeared in the standard and after all these years, and various clarifications and modifications, the industry in my opinion, is finally starting to recognize/understand/enforce the actual requirements. I am seeing more and more rack facilities being told that they need additional sprinklers due to their storage arrangement and the classification as solid shelving.

To clearly state the issue, NFPA 13 defines solid shelving and states that it is not the shelving material housing the commodity (stored material) alone that defines “solid shelving”. In fact, it is entirely possible to have no shelving and still be classified as “solid shelving”, thus requiring in-rack sprinklers. The load (commodity) itself can define solid shelving. This is a huge change to the requirements and first appeared in the 1999 edition of the standard.

Many, including myself, questioned the committee as to whether this interpretation was correct. In 2016, I attempted to add a discussion on cantilever shelving to the Annex so that it was obvious to everyone that even though no shelving is present, this could still constitute solid shelving. I submitted the following as a Public Input for the committee to consider:

A storage arrangement could be classified as solid shelving even if there is no shelving material provided. Cantilever shelving with wide loads could be classified as solid shelving and require additional protection.

As an example, I made reference in my question to drywall sheets stacked on cantilever shelving and intended to be as obvious as I could regarding what constitutes solid shelving. The Input was rejected by the committee with the statement that:

This section implies that Solid Shelving only consists of plywood shelves on the shelf beams, yet the definition of solid shelving in Section covers so much more. By definition solid shelving can be present even if there is no shelving material used at all so to define solid shelving as plywood is confusing and weakening the intent of Section

Basically the argument for rejection is that it is sufficiently explained and my comment was clouding the issue. (note that I did not reference plywood in my submittal and the committee referenced plywood to state that it is not just plywood that forms a solid shelf) I believe that the response is important with the key words being “...solid shelving can be present even if there is no shelving material used at all...”

Photo 1 illustrates the point that I am trying to make. The cantilever racks in the photo are supporting metal studs that create a solid barrier of 4 feet wide by 32 feet long. This should be evaluated as a solid shelf of 128 square feet (4’ x 32’) and, in accordance with the requirements of NFPA 13, mandate in-rack sprinklers below every shelf since it is over 64 square feet. Yet when the code official walks into the building, before approving occupancy and use of the racks, there is no storage on the racks. Standing on the ground and seeing the ceiling above, the official almost always determines that the arrangement is obviously open shelving (or no shelving) and in-rack sprinklers are not required. Note that these requirements apply regardless of the commodity classification. The photo depicts a non-combustible, Class I commodity, i.e., metal studs and metal pipe. This configuration would still require in-rack sprinkler protection on every level per the solid shelving definition.

Photo 1: Metal Studs on Cantilever Racks

I have had numerous discussions with clients, contractors and rack storage manufacturers trying to explain this requirement. To many of them, no shelving is obviously “open shelving” and therefore does not meet the definition of “solid shelving”.

Illustrating the issue is one thing, but without discussing the actual language, this blog post might be viewed as an attack on NFPA 13 and that is not my intent. The committee is correct in stating that the language clearly shows that this should be solid shelving, and yet in all my years of experience, I have never seen a code requirement that is so misunderstood. I cannot tell if it is misunderstood because people don’t want to read what it says or because to them it is not passing the “smell” test.

I am convinced that this subject is so important that we have to look at the actual requirement and review how we got to this point. I have had numerous discussions with individuals that work in the storage field who are adamant that the committee is not requiring sprinkler protection when there is no shelving material or when wire mesh is available. Having been told that cantilever racking with no shelving can be considered solid shelving, all that I can respond to is that the committee clearly intends to have the load geometry and configuration be considered when determining if the solid shelf rules apply or not.

In order to explain this requirement, I plan to prepare a series of blog posts exploring this in depth. This blog series will start with the current code requirements and then address the original fire testing and show the changes to the requirements that have occurred over the 17 years that the solid shelving rules have appeared in the standard. Once complete, I hope to have a document that can be assembled into one longer format, presenting the solid shelving requirements from beginning to end. If nothing else, I hope to open people’s eyes to what the actual requirements are and encourage an open discussion on these requirements.

If you are concerned about what is written, then you must get involved in the standard/code process and submit changes. It is your standard/code that is imposing these requirements and you should have your voice heard. If you agree with the changes then let’s see that they are applied throughout the storage field and be sure that designs are in accordance with the requirements. You can submit comments on the proposed changes for the 2019 Edition of NFPA 13 between March 1 and May 10, 2017. Just go to and click on the next edition tab.

The next blog will discuss the requirements as they appear in the 2016 edition. Future blogs will show the original criteria, discuss what tests developed the criteria and explain the evolution of the document through the various editions.

As always, I welcome your comments:

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