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Fire, Life Safety

Interpreting revisions to NFPA 13-2019

Know how to navigate the restructured NFPA 13 sprinkler standard and understand technical changes

By Kelly Finzel April 16, 2020
Courtesy: Arup

Learning objectives

  • Learn about the organizational changes to NFPA 13.
  • Review the roadmap tool created for correlating the 2019 edition to the 2016 edition.
  • Highlight some revisions to the standard that impact sprinkler system design.

NFPA 13: Standard for the Installation of Sprinkler Systems provides technical criteria for the design and installation of sprinkler systems. The first edition of this standard was formed in 1896 and today it is a flagship standard for the NFPA.

NFPA 13 is the sprinkler design standard in effect in jurisdictions throughout the United States as it is incorporated into Chapter 35 of the International Building Code, the model building code published by the International Code Council. Various editions of the IBC are adopted throughout the country and serve as the framework for local building codes. Through this adoption, state and local governments also adopt the technical requirements of NFPA 13.

Whereas the building code identifies when an automatic sprinkler system is required, NFPA 13 outlines the system’s technical design requirements. This standard defines system terminology; classifies hazards; delineates installation criteria for sprinklers, obstructions, piping and hanging and bracing; provides various design methods; and identifies technical performance criteria for calculation of systems; and much more.

It serves as a comprehensive tool and reference that enables engineers to design sprinkler system that mitigate the effects of fire, prevent fire related deaths and limit property loss. Given its widespread adoption, revisions to this standard significantly impact the sprinkler design community.

Restructuring a standard

NFPA 13 has been revised over time to keep pace with new technology and changes in the built environment that affect system performance. Modifications to this standard follow NFPA’s three-year revision cycle, with the most recent edition published in 2019. The 2019 edition has seen significant change due to reorganization and restructuring of the document. Although these changes were incorporated in this edition, the restructuring follows recommendations made by the technical committee on sprinkler system discharge criteria (AUT-SSD) during the previous revision cycle.

Figure 1: The installation of in-rack sprinklers is shown for storage in a distribution warehouse. In-rack sprinkler requirements are addressed in Chapter 25 of NFPA 13- 2019. Courtesy: Arup

Figure 1: The installation of in-rack sprinklers is shown for storage in a distribution warehouse. In-rack sprinkler requirements are addressed in Chapter 25 of NFPA 13- 2019. Courtesy: Arup

The task of incorporating organizational changes to this document was undertaken by the newly created NFPA 13 Restructuring Task Group. This committee was charged with addressing redundancies, implementing consistent structure across the document and reviewing overall organization to replicate the flow of the sprinkler system design process.

One major change in the 2019 edition includes dividing the existing chapter on sprinkler criteria into multiple chapters. This results in Chapter 8 from the previous edition, the predominant driver for installations outside of storage applications, becoming several chapters, with one dedicated to general sprinkler guidelines and several others each dedicated to a specific sprinkler technology. The latest edition breaks out requirements for standard coverage sprinklers, extended coverage, residential, control mode specific application, early suppression fast-response and other special sprinklers.

Providing a dedicated chapter for each sprinkler technology clearly delineates where the requirements for a sprinkler type begin and end as each is provided with a different leading section number. This simplifies navigating the standard for system designers.

The existing storage chapters have been broken out in a similar fashion in the 2019 edition. The existing chapter for general storage requirements remains and is now followed by a chapter dedicated to ceiling-level sprinkler protection using each of the following technologies: control mode density area, CMSA and ESFR sprinklers. These are followed by a new chapter that consolidates the requirements for in-rack sprinklers into a single location. This method of restructuring provides consistency throughout the standard and merges requirements that were repetitive or conflicting in previous editions.

Additionally, NFPA 13-2019 relocates some existing chapters to earlier in the document, such as the requirements for the installation of underground piping. These requirements were previously located in Chapter 10 and have been moved to Chapter 6 in the 2019 edition. These changes have resulted in the standard’s technical requirements following the order of design for an automatic sprinkler system.

Together, all of these changes improve the day-to-day functionality of the document by reducing the need for designers to flip back and forth between various locations within the document and following the typical system design sequence.

A roadmap to changes

The reorganization implemented in NFPA 13-2019 resulted in significant change from the previous edition. To prevent the loss of information during revisions and help facilitate future review and approval of the revised document the Restructuring Task Group tracked all of the revisions made to the document during their work. The result of this effort is a 26-page roadmap that correlates section numbers from the previous 2016 edition to the 2019 edition.

Figure 2: The technical requirements for automatic sprinklers like this standard coverage pendent sprinkler are now provided with a dedicated NFPA 13 chapter based on sprinkler technology. Courtesy: Arup

Figure 2: The technical requirements for automatic sprinklers like this standard coverage pendent sprinkler are now provided with a dedicated NFPA 13 chapter based on sprinkler technology. Courtesy: Arup

The NFPA 13 2016-2019 Roadmap is user-friendly and includes two adjacent columns, one that indicates a section number from the 2016 edition and a second indicating the correlating section in the 2019 edition. The sections are listed in numerical order from the 2016 edition and include headings to subdivide sections by the 2016 standards’ chapters. Section numbers from both editions also include an asterisk to indicate where explanatory material is included in Annex A, as is typical throughout NFPA’s standards.

The Roadmap is a streamlined tool that can be used by designers to ease the transition between the two latest editions of the document. This tool allows users to quickly correlate section numbers between editions will help those designing sprinkler systems be efficient as they navigate a new standard and allow designers to focus their efforts on updates to the technical content. The 2016-2019 Roadmap is published as part of NFPA 13-2019 and is located at the end of the standard after the index.

Clarifications and changes to technical requirements

In addition to its restructuring, the 2019 edition incorporates clarifications and technical changes into the standard. Changes follow the marking system that is uniformly applied to the NFPA standards. Revised language is highlighted in gray whereas new sections are annotated with the letter “N” to the left of the section number. In some cases, sections marked as new are indicative of requirements from the previous edition that have been split into multiple sections.

For example, water mist systems are addressed in NFPA 13-2019 sections 1.1.2.1 and 1.1.2.2, clarifying that water mist systems are not considered fire sprinkler systems and must comply with the requirements of NFPA 750: Standard on Water Mist Fire Protection Systems. These sections are marked with the N designation, but also appear in the 2016 edition combined under section 1.1.2. It is important for designers using the standard to understand the markings used to identify changes between varying editions and the types of changes this might signify.

Figure 3: New installation requirements are shown for the installation of residential pendent sprinklers at beams. Courtesy: Arup

Figure 3: New installation requirements are shown for the installation of residential pendent sprinklers at beams. Courtesy: Arup

Revisions to NFPA 13-2019 are more explicit in outlining coverage requirements by refining or adding to the standard’s language. Many of the clarifications included in this latest edition of the standard acknowledge common questions asked to sprinkler system designers by the larger design community and amend or supplement language to address these questions without ambiguity. Selected revisions and technical amendments are:

  • Section 1.3.2 explicitly addresses the level of protection required by NFPA 13. This requirement, which was previously included in Chapter 4 of the 2016 edition, specifies that sprinkler protection must applied throughout a building unless omission of sprinkler coverage is specifically permitted by another section of NFPA 13. This section outlines the requirements for automatic sprinkler system coverage for designers when coverage requirements are in question. Relocating this information to Chapter 1 represents the restructuring efforts incorporated by the Restructuring Task Group to provide consistency and clarity of requirements throughout the standard.
  • The requirement for sprinkler coverage within electrical equipment rooms is commonly reviewed by building design teams. NFPA 13-2019 sections 9.2.6 and 9.3.20.1 revise the allowances for the omission of sprinkler coverage in electrical equipment rooms. Previously one of the four criteria necessary for omitting sprinkler coverage in such spaces was the use of only dry-type electrical equipment. NFPA 13-2019 revises this condition to permit the use of liquid-type electrical equipment where K-class fluid is used, expanding the applications where such a room may be permitted to exclude sprinkler coverage. Additionally, the language is revised in another of the criteria permitting sprinkler omission to make plain that no storage is permitted in electrical equipment rooms. Previous editions of NFPA 13 only prohibited combustible storage. This clarification simplifies the sprinkler omission criteria and clearly restricts any storage.

Residential sprinklers

Chapter 12 of the 2019 edition incorporates expanded requirements for the installation of residential sprinklers where there are beams below the ceiling plane for flat ceilings and sloped ceilings.

  • Section 12.1.8.1.1 outlines new requirements permitting the installation of pendent and upright sprinklers where beams are present. These requirements limit beam depth to 14 inches, ceiling height to 24 feet, a maximum compartment of 600 square feet and a maximum ceiling pitch equivalent to 8 inches of rise in a horizontal length of 12 inches.
  • New requirements for the installation of pendent, recessed pendent and flush-type pendent sprinklers below and next to beams are outlined in section 12.1.8.1.2 The installation of pendent sprinklers below beams is permitted based on a maximum beam depth of 14 inches where the sprinkler deflector is installed between 1 to 2 inches below the beam. The distance of the deflector below the beam is permitted to vary where the sprinkler is installed in accordance with the manufacturer’s installation instructions. The installation of pendent sprinklers adjacent to beams is also permitted where the sprinkler centerline is a maximum of 2 inches from the beam edge and the deflector is installed 1 to 2 inches below the beam. Other installations are permitted for flush-type pendent sprinklers where the location of the deflector is in accordance with the manufacturer’s instructions.
  • The requirements listed in the two bullets above are not relevant to the installation of concealed pendent sprinklers where beams are present. New requirements for these permit their installation only for beam depths up to a maximum of 4 inches, in accordance with section 12.1.8.1.3. This new requirement for maximum beam depth for use of this sprinkler technology could significantly impact the layout of sprinkler systems in residential applications and will require designers to review the ceiling design in-depth before selecting sprinkler system equipment.

Automated valves

  • Section 16.9.4 and its subsections outline new requirements for the use of automated valves. Per these requirements, listed valves with automated controls are allowed for use where the assembly is installed with a position indicator and provided with connection to a remote supervising station. Automated valves are also required to be functional be manual means.

Hydraulic calculations

  • Calculation requirements for deluge systems at proscenium openings are addressed in section 19.4.3.3. This section requires that all open sprinklers attached to the deluge systems at these types of locations must be included in the hydraulic calculations.
  • Additional clarifications are provided for hydraulic calculations for sprinkler-protected glazing. Section 19.4.4.1 specifies that calculations must be performed based on the number of sprinklers in length of glazing equivalent to the number of sprinklers in the branch line as determined using the density/area calculation method outlined in Chapter 27. Additionally, section 19.4.4.2 requires that where it is determined that a fire will activate sprinklers in sprinkler-protected glazing and at the ceiling the hydraulic calculations must be balanced to the calculated area demand. Hydraulic calculations must be selected to include a design area that includes ceiling level sprinklers adjacent to the sprinkler-protected glazing, per section 19.4.4.3.

Storage requirements

The requirements for storage applications are now located in NFPA 13-2019 Chapters 20 through 25.

  • Chapter 20 provides the general sprinkler requirements for all storage installations and includes new language upfront to outline the general approach for the design of automatic sprinkler protection for storage applications. This includes section 20.2, a step-by-step methodology for sprinkler system designers to determine the conditions that will govern the coverage required and which subsequent chapters pertain to the installation being considered.
  • Chapter 22 incorporates sprinklers with a K-factor of 25.2 into several tables for design criteria where using CMSA sprinklers are used in storage applications.

Systems acceptance

  • Section 28.2.1.2 clarifies that pressure loss during hydrostatic testing of the system to be identified by visual observation of leakage or drop in gauge pressure.
  • Pipe or tubing specifically tested and listed for use in dry pipe and double interlock pre-action system are allowed to be tested per the limitations of their listing, in accordance with section 28.2.2.3.
  • Section 28.2.3.1.1 requires activation of a fire alarm signal where waterflow monitoring is required by the locally adopted fire alarm code.
  • Requirements for the inspection and testing of automated equipment and devices are included in 28.3 and its subsections. This testing and acceptance criteria aligns with the incorporation of this equipment into Chapter 16, as discussed above.

Existing systems

In previous editions of NFPA 13 requirements for existing building applications were dispersed throughout the standard. The 2019 edition consolidates all existing building requirements into Chapter 29, following the organizational changes implemented throughout this edition. This change will significantly improve an engineer’s ability to quickly navigate all of the applicable requirements for these applications.

The revisions to NFPA 13 in the latest revision cycle were incorporated with the end user in mind. The supplemental language and clarifications, in addition to the restructuring of the standard to follow the design sequence for automatic sprinkler systems exemplify these efforts. The 2016-2019 Roadmap that was developed and incorporated into the standard provides a tool to minimize the effect of the reorganization.

Recognizing the time interval between publication of the latest edition of NFPA 13, adoption by the model building code and local jurisdictions, designers have time and the right tools in hand to adapt to the reorganization and technical revisions in NFPA 13-2019.


Kelly Finzel
Author Bio: Kelly Finzel is a senior fire engineer at Arup. She has more than a decade of experience in the design of automatic sprinkler systems. She holds a master’s in fire protection engineering and is an alternate on the NFPA 101 technical committee for building service and fire protection equipment.