NFPA 13 2019 – Opinion on the In-Rack Chapter

July 8th, 2019

The new layout of NFPA 13 may be beneficial for new users of the standard, but it can also create confusion and dismay for experienced users as they will have to search and relocate familiar regulations and determine how these new, sometimes reworded and reformatted sections, tables, and paragraphs relate to each other. This is especially true when looking at the new in-rack Chapter 25 of NFPA 13. After using the new standard for some time now, and Chapter 25 in particular, which left me wondering on more than one occasion, I feel a need to share my experiences and observations concerning this steep learning curve. Here is a summary of my conclusions on the reformat.

Author: Michael Klausbruckner

NFPA 13 2019 Chapter 25

With the reformat of NFPA 13 standard, all in-rack protection schemes were consolidated in a single chapter. This new and rather large Chapter 25 in NFPA 13 2019 Edition lists all the in-rack regulations previously found in their respective commodity-type chapters (i.e., Class I-IV and Rubber & Plastics chapters for rack protection). Furthermore, it includes an expanded list of “Alternative Protection” schemes as well as solid shelf in-rack protection schemes for “Miscellaneous Storage.”

At this point, I would like to note that the well-known “Alternative Protection” schemes are located in Chapter 25 and not in Chapter 24, which has a very similar title (i.e., “Alternative Sprinkler System Designs for Chapters 20 through 25”). Chapter 24 (covering overhead-only, CMSA-type sprinkler protection with K-Factor 25.2 and EC type sprinklers) should really have been positioned after Chapter 25 and not before it, as was the case in NFPA 13 2016 Edition (Chapter 21). NFPA’s reasoning for this position in the new version of the standard relates to Chapter 24’s discussion of overhead-only sprinkler schemes, which is similar to other “overhead-only chapters” listed before it. The NFPA 13 committee wanted to help clarify the differences between these two chapters with the chapter titles, so Chapter 25’s in-rack related “Alternative Protection” schemes are now called “Alternative In-Rack Sprinkler Protection Options That Are Independent of the Ceiling Sprinkler Design.”

Quick View (Storage Chapters)

  • Chapter 21: CMDA for all overhead-only protection, including different commodities and storage methods. See Chapter 25 for cases when in-racks are required in combination with overhead CMDA. The sprinkler design criteria for retail (mainly using K-25.2 Extended Coverage Sprinklers) have been consolidated into this chapter, along with other CMDA sprinkler-based “Special Designs of Storage Protections” found in Chapter 20 of the 2016 Edition of NFPA 13, such as baled cotton storage, carton record storage, compact storage, and high bay record storage. This is an unusual location for these types of storage protections, making this (CMDA) subsection quite long and harder to read. I received some professional feedback that it may include sprinkler design options that would normally get lost in the shuffle of subsequent chapters. While this confusion may occur for new users, this is probably less likely for experienced users.
  • Chapter 22: CMSA for all overhead-only protection, including different commodities and storage methods. See Chapter 25 for when in-racks are required in combination with overhead CMSA. However, shouldn’t this chapter also list some of the Chapter 24 protection schemes? After all, they are CMSA-based, and this proposed new structure would therefore align with the overall structure of the previously discussed chapter (Chapter 21). Of course, it would make this chapter longer than it currently is, but it is already one of the shortest storage chapters.
  • Chapter 23: ESFR for all overhead-only protection, including different commodities and storage methods. See Chapter 25 for when in-racks are required in combination with overhead ESFR. This chapter also includes ESFR-specific “Special Designs of Storage Protection” found in Chapter 20 of the 2016 Edition of NFPA 13.
  • Chapter 24: Alternative overhead-only sprinkler designs. This chapter consists of unique designs with very specific applications for different commodities and storage methods. Many of these designs had been in Chapter 21 of the previous editions of NFPA 13 (Extended Coverage, CMSA, K-25.2 for open frame rack storage or solid piled storage, etc.).
  • Chapter 25 (discussed here): Any sprinkler option requiring in-rack sprinklers, regardless of the overhead sprinkler in question, can be found in this chapter. This also includes “Alternative In-Rack Sprinkler Protection Options Independent of the Ceiling Sprinkler Design.” In the 2016 Edition of NFPA 13, these ceiling independent protection schemes were known as “Alternative Protection” and were previously located in Section (for Class I-IV) and (for Group A Plastics).

Chapter 25 in More Detail

The new Chapter 25 discusses general application requirements for any rack protection schemes and any type of commodity that requires in-rack sprinklers, including CMDA, CMSA, and ESFR protection schemes.

In order to simplify the application of the rather large Chapter 25, a scope for the chapter is presented providing guidelines that should help practitioners in specifying in-rack sprinklers (25.1.1). This is likely quite useful when targeting new users, rather than experienced ones, who typically want to “get down to business” quickly. Hopefully, everyone will read it at least once as it does provide a brief table of contents for this chapter.

Solid Shelf protection schemes for racks requiring the installation of in-rack sprinklers are now separated out in Section 25.6. They also include “Miscellaneous Storage and Low-Piled Storage” in-rack requirements in the case where solid shelves are required.

New K-25.2 CMSA protection schemes were added to Tables 22.2 to 22.5, allowing for higher maximum ceiling heights (30 ft or 40 ft, depending on the respective table). Please note that Table (Class I-IV, rack storage for storage heights larger than 25 ft, 2016 Edition) is completely missing in the 2019 Edition. Also, non-in-rack protection options in Table (CMSA, K-19.6, rack storage heights above 25 ft) of the 2016 Edition are missing. However, updates to the standard in order to correct these omissions are being produced.

The “Alternative Protection” schemes are now expanded to include two additional protections options (Options 2 and 3) in addition to the 2016 scheme (Option 1). Both of these new options allow for very high storage heights while only requiring one to two levels of in-racks. These are cost-effective, ceiling-independent protection schemes that can also be applied at warehouse locations, where available sprinkler water flow is limited. These two new options are the only substantive changes to Section 25.8 in the 2019 Edition, while the remainder of this sub chapter is effectively a re-format.

Pre-action (dry-pipe) CMSA systems with in-rack sprinklers are also covered here.

Key Changes to Chapter 25

  • Reformat of Chapters 13, 16 and 17 of the 2016 Edition, which includes the collocation of all in-rack sprinkler schemes into one large chapter (In-rack-based protections were removed from the protection tables of the preceding overhead-only sprinkler chapters)
  • Addition of a new “Scope” section at the beginning of Chapter 25 to provide an overview of this chapter and to facilitate the correct specification of in-rack protections
  • Renumbering, rewording, and reformatting of in-rack regulations, which also includes new tables replacing the regulation paragraphs found in Chapters 13, 16, and 17 of the 2016 Edition
  • New K-25.2 CMSA protection options for 30-ft and 40-ft maximum ceiling heights
  • Two new “Alternative Protection” schemes that require only one to two levels of in-racks to protect various types of commodities

Key Observations

The pros:

  • Found early in the chapter, sprinkler designers will appreciate the discussion of important sprinkler application requirements (see Sections 25.1.3), such as in-rack sprinkler system size, system control valve application based on the number of sprinklers, overhead design criteria in combination with in-rack sprinklers, and sprinkler water flow alarm and building steel protection requirements.
  • Miscellaneous and Low-Piled Storage (25.2.2) in-rack regulations (required since the 2016 Ed. for racks fitted with solid shelves) are listed early in Chapter 25.
  • These regulations are logically followed by CMDA (25.2.3), CMSA (25.2.4), and ESFR (25.2.5) protections, if in-racks for all types of commodities (Class I-IV, Rubber & Plastics, Rubber Tires) are required.
  • In-rack spacing requirements and characteristics are listed in Sections 25.3, 25.4, and 25.5, a logical place for these types of discussions. This also allows users to find the sections more easily.
  • This is followed logically by Solid Shelf in-rack protection requirements (25.6).
  • While outside of the discussion of Chapter 25, it is notable that the installation requirements for CMDA, CMSA, ESFR, Extended Coverage, etc., are now separated by sprinkler type and summarized in each of their respective chapters (Chapters 10–15).

The cons:

  • The wording in certain sections and regulations have unnecessarily changed in several cases, making it difficult to search for known keywords or specific paragraphs from previous editions. However, we will attempt to address this issue in the near future.
  • The “Roadmap” listed in the appendix of the standard (its intended purpose is to provide section number cross-references between 2016 and 2019 regulations) is incomplete. Update October 26th 2019: see NFPA 13 2019 To 2016 Cross Reference.
  • Horizontal Barrier requirements (25.7) should logically precede Solid Shelf protection requirements (25.6) and should be placed directly after in-rack spacing requirements (25.5). Otherwise, they can be easily overlooked.
  • The numbering scheme applied to individual sub chapters (25.x) requires review (e.g., CMDA, CMSA, ESFR regulations should more appropriately be numbered 25.3 to 25.5. In-rack spacing and horizontal barrier requirements and characteristics should be summarized under proposed Section 25.6 and not be separated out (currently found in 25.3, 25.4, and 25.7).
  • Concerning Section 25.8, “Alternative In-Rack Sprinkler Protection Options That Are Independent of the Ceiling Sprinkler Design,” these schemes require in-rack sprinklers and can be located in this chapter, but they make it unnecessarily long and may reduce overall usability. They should be moved to a standalone chapter, as is the case for Chapter 24.
  • Familiar in-rack design specifications are now separated from the various sub chapters in Chapter 25 (with the exception of Section 25.8), such as the number of in-rack sprinklers or the minimum required flow/pressure from in-rack sprinklers, and are now found in Tables and, located at the end of this chapter. Thus, they are easily overlooked. You may want to make a note of these tables’ locations.
  • A “run-on” list of in-rack figures and figure captions, requiring careful study of each figure caption to find the applicable protection scheme. The associated tables, specifying the applicability of these figures to various rack types, storage heights, and commodity types, are interspersed among these figures, thus requiring paging back and forth when searching for them.
  • Similar usability issues exist for important protection restrictions, such as sprinkler arrangements due to excessive clearances (Section 25.9.5) and adjustments to ceiling-level (overhead) sprinkler density due to storage height (Table These should be located at the beginning of the chapter rather than being mixed in throughout the rest of the chapter.


The new in-rack sprinkler Chapter 25 collocates all existing and new protection schemes for 2019 into a single chapter in order to improve the workflow for users. It must have been a massive undertaking to reformat the entire standard and, on a smaller scale, to extract specific in-rack regulations into one large chapter. Perhaps most importantly, with the release of the new standard, NFPA showed that they truly listened to user suggestions to improve usability for various storage chapters. These changes certainly represent a major step, but only time will tell if it is a step in the right direction. Until then, I believe that this reformat will serve as a strong starting point in making sprinkler design more accessible and the standard easier to navigate while also making it more intuitive for users to locate appropriate sprinkler regulations.

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