top of page
  • Jerry Schultz, P.E.

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:

  • Jerry Schultz, P.E.

For years I have had the pleasure of teaching the three day seminar on automatic sprinklers on behalf of NFPA. For those of you who have attended a class that I taught, thank you. For those of you who haven’t heard me speak, I invite you to register for a program. In the seminars, I get the opportunity to present the standard and illustrate points with anecdotes, stories and real world adventures. Some of these come out in this blog, and one that really hits home with me is the “plasticization” of the world that we live in. In an earlier blog, I wrote about NFPA 25 which requires the inspection, testing, and maintenance of the sprinkler system, but excludes the evaluation of the adequacy of the sprinkler system. The example I used is the modern day garden hose reel. This product has changed from a metal product 35 years ago to a completely plastic product today. My example could just as easily have been an IBM “Selectric” (trade name for an electric typewriter) typewriter verses a notebook computer or the Tonka metal body truck that I grew up with verses the plastic trucks kids play with today. (Not to mention, the electronics stuffed in these newer trucks that have lights and sirens.) These are obvious changes but the issue is so pervasive that we sometimes miss the concept.

If you haven’t seen it, this video shows a side by side fire in a front room where the front room on the left has natural material built furniture, manufactured 40 years ago (couldn’t tell if this was shag carpeting but did notice no disco ball) while the front room on the right has modern day synthetic material built furniture (

One couldn’t ask for a better example of how pervasive and even subtle the plasticization of society is. As evident in the video, the backing on the carpet is synthetic as well as today’s drapes and furniture which are more flammable than cotton, silk or leather and lead to a much more severe, rapidly developing fire.

Keeping in mind that we are talking about the plasticization of society, let’s look at two editions of NFPA 13, Standard for the Installation of Sprinkler Systems, the 2013 and the 2016 editions. Figure of the 2013 edition stated that a Group A plastic that was exposed and expanded and stored on racks was outside of the scope of Chapter 17.

As recently as 2013, we did not know how to address this hazard. In the 2016 edition of the standard, criteria was added for expanded, exposed Group A plastics on racks. The NFPA 13 committee added the criteria based on a series of fire tests conducted by Underwriters Laboratories (UL) under the direction of the Fire Protection Research Foundation. These tests resulted in the current criteria that was added to NFPA 13, (Section up to 25 feet and Section over 25 feet).

This criteria is tough because, not only are vertical barriers required to run the full height of the racks, but a large amount of water is required of the water supply.

For storage over 25 feet, one has to provide a sprinkler with a k factor of 25.2 and assume 12 sprinklers flowing at a minimum pressure of 60 psi. This yields a minimum individual sprinkler discharge of 195.2 gpm. Multiplying by the required 12 sprinklers, means the minimum design flow for the system, (not accounting for inside or outside hose stream allowance) is 2,342 gpm.

Kerry Bell of UL explains the fire test in a video ( that illustrates the severity of the fire.

At first blush it is easy to say, I don’t have polystyrene meat trays stored like this so how does this affect my warehouse? The polystyrene meat tray represents a reproducible Group A, expanded exposed plastic and is meant to represent any expanded, exposed Group A plastic. This classification includes items such as furniture, car bumpers, coolers, certain toys, bedding, and yes, garden hose reels. I would strongly suggest reviewing the Annex in the 2016 NFPA 13 edition where the commodity classifications were completely rewritten to see what products are considered an expanded, exposed Group A plastic. (Note—one of the best changes in the 2016 edition of NFPA 13 is the rewrite of the commodities. The commodity list hadn’t had a major revision since its’ original insertion in NFPA 231 and 231C in the 1970’s.)

I am always asked if NFPA 13 is a retroactive standard and I respond with the classic response—No, per Section 1.4 “The provisions of this standard reflect a consensus of what is necessary to provide an acceptable degree of protection from the hazards addressed in this standard at the time the standard was issued.” I admit, when a new requirement is added for something that has never been addressed before, I believe one has to at least look at the protection scheme that had previously been accepted (probably an engineered approach) and consideration should be given as to whether these new requirements should be retroactive. Keep in mind there are acceptable alternative designs and that you, as a consultant, a designer, an insuring authority or the AHJ (by definition, the term AHJ may cover some or all of these positions and is not intended to apply exclusively to a governmental agency) will be required to assess the previous protection scheme and make a decision if it is still acceptable or should the new requirements be applied. Also keep in mind that in Section 1.4.2 the AHJ has the authority to “apply retroactively any portions of this standard deemed appropriate.”

This is a long way to get to one major issue that I am starting to see in warehousing. Recently I have been involved with several clothing warehouses along with several paper storage facilities. In both cases, there have been discussions on the potential for taking clothes and placing them in plastic totes or storing the paper in plastic totes, in order to reduce the likelihood of the clothing or paper being damaged should a sprinkler activate. Does this change the fire scenario? Of course it does. What is required to be done? One must review the arrangement and make a decision as to whether this becomes a plastic fire. If so, does it become an exposed, expanded Group A plastic on racks and now we have to add barriers, provide a k25 sprinkler, increase our main size, and possibly provide a bigger fire pump? It goes on and on and yet the owner of the warehouse, sees it as protection for the product and not an additional fire hazard.

Next month, I will start discussing solid shelving in racks unless something happens in the industry. Until then, as always, I welcome your comments:

  • Jerry Schultz, P.E.

In my last blog post, I wrote about a cushion on water supplies and raised the question if the system is properly designed, is a cushion (hydraulic buffer) required? I pointed out that NFPA 13 appears to be heading down a path where we will soon be mandating a cushion. In an earlier post, I addressed NFPA 25 and identified a gap in the standard. This blog post will attempt to address both of these issues together and make a point that even with a cushion, the need for diligence in reviewing NFPA 25 results, along with an understanding of basic water supply is critical. Let us also agree that NFPA 25 is NOT a design, construction, or installation Code or Standard. Designers are not required to meet NFPA 25 during design, inspectors are not required to verify installations during the punch list phase of a project, and final acceptance tests are not required by NFPA 25. NFPA 25 assumes that the original installation was installed and approved correctly, and that the existing system is considered adequate/acceptable. NFPA 25 is an Inspection, Testing, and Maintenance (ITM) standard and cannot apply to systems that have not yet been built. It is probably the ultimate retroactive standard because the latest edition is what the system is to be analyzed against.

Not too long ago, one of my clients who operates a building in a large Midwestern city, assigned an individual to the property. This individual was required to read the sprinkler gauge on a quarterly basis and noticed that the gauge that had read 65 psi for the last 5 years was suddenly reading 35 psi. He quickly contacted us and asked if there was a problem with the system. (As an aside, once I was brought in to review a hospital’s ITM program and found that the inspector, in doing their monthly inspection had recorded 0 psi on the gauge for the last 9 months. He was doing what he was told, recording pressures.) Back to the original story. We got involved with the project and identified that the water supply had been decreased by 30 psi by the city. It seems that this one area of the large city had its own supply and the city had decided to connect this leg back to the remainder of the underground grid which was at the lower pressure. This lower pressure obviously impacted the sprinkler system (again, last month we talked about 5 psi or 10% cushion, never a 30 psi cushion) and caused the sprinkler system to be deficient (demand exceeded supply).

Upon further investigation, I received from the local municipality’s water department, a document written in the 1920’s indicating a legal covenant between the municipality and the original building owner that the water department was only required legally to provide 20 psi at the facility. Regardless of the fact that the sprinkler system which was installed in 1992, had been provided a minimum pressure of 65 psi and had used this value in their design of the sprinkler systems.. The municipality in essence, exceeded their legally mandated covenant and now by reducing the pressure, it was up to my client to adjust and redesign the system. In this case, we had to design a fire pump for the existing system. Needless to say, we designed the pump using the covenant number (20 psi).

In another Midwestern village, the municipality elected to decrease the water supply by 15 psi in order to reduce leaks on their piping. This was done due to a concern about the age of the pipe. Once again suddenly the sprinkler systems are under-designed.

In another situation, my client is connected to a 100 year old underground pipe that appears, based on a hydraulic gradient analysis to have an equivalent C factor of 60. This 300 foot long pipe runs for a portion under the highway and is scheduled for replacement, but the project has been delayed for 5 years while funding keeps getting cut. The friction drop through this pipe is impacting the sprinkler system so that once again, a system is under-designed. On this one, static pressure is where it should be. It is only when flowing water that one sees the deficiency.

Municipalities across this country are facing an aging infrastructure and a need for the water departments to reduce costs, this seems to be a re-occurring theme, affecting the fire protection of structures and I wonder, the fire service capabilities of the communities that they serve.

War stories exist everywhere and I am sure that you have some yourself. I walk into the building and check the main drain tags and notice that the system used to have a static pressure of 90 psi and for the last several years, static pressure is 65 psi. Yet the hydraulic placard (yes it is present and legible) reads:

This system is designed to provide a density of 0.20 gpm per square foot over the most remote 1500 square feet when supplied with water at a rate of 595 gpm at 78 psi…

It should be obvious to all that if the system requires 78 psi at 595 gpm and I only have 65 psi at 0 gpm, there is a problem. Yet the main drain test had changed in 2002 so for 13 years, the sprinkler system water supply was no longer adequate and nobody commented.

California drought conditions, hydrants flowing water over the hot summer leading to excessive seasonal low conditions, water departments decreasing water supplies to reduce leakage and save money, the aging infrastructure and pipes deteriorating are all conditions that the cushion we have discussed both in this and last month’s blog cannot address. So we go back to, who should notice this? Whose responsibility is it to identify a problem with the existing water supply?

Getting back to my point, NFPA 25, Standard for the Inspection, Testing and Maintenance of Water Based Suppression Systems, does not require the contractor performing the inspection, testing, and maintenance of these systems to evaluate the system’s water supply, (let alone if the hazard of the facility has increased), thereby making the system less than adequate. In a previous blog, I addressed the hole in NFPA 25 where no one assesses the adequacy of the system but here is a gap that is easier to address. This is the purpose of NFPA 25, it is used to evaluate “wear and tear” on the system components as described in an NFPA Journal column two years ago. Someone who is qualified needs to review the inspection report and identify these issues. A person recording weekly pressures of 0 psi is obviously qualified to record pressures but not qualified to read and understand the data collected. The decrease in a water supply for whatever reason is becoming a bigger and bigger issue. Owners need to understand what information is being collected and review those results so that there is always an adequate water supply for fire protection and fire service. The cushion discussed in last month’s blog does not account for the deteriorations we are seeing.

It mostly works well when someone who understands the importance of the information gathered is involved, someone who can interpret the data collected, reviews the gathered data, and can add context around what that data is saying. The individual recording the weekly pressure notices the decrease like my client did. The individual who reviews the main drain test notices that the pressure has decreased below what it has been for years. The only way to address this is to ensure that a qualified individual is reviewing reports and not just filing these in a drawer. The information is there but it needs to be pulled together.

I find it interesting that as I write these blog posts, they are so interrelated. These last two, which started to address a deterioration of the water supply, highlights the need for someone knowledgeable to review the data gathered in an NFPA 25 inspection.

As always, I welcome your comments:

Featured Posts
Recent Posts
Search By Tags
Follow Us
  • LinkedIn Social Icon
  • Facebook Basic Square
bottom of page