What’s new to NFPA 13 and what to expect in future editions

Changes to the 2016 edition of NFPA 13 are evaluated along with what to expect in the 2019 edition.

By Raymond A. Grill, PE, FSFPE, LEED AP, Arup, Washington, D.C. April 28, 2017

Learning Objectives

  • Review changes made to the 2016 edition of NFPA 13: Standard for the Installation of Sprinkler Systems.
  • Discuss the updated organization to the 2019 edition of NFPA 13.

Standards that are regularly applied in daily practices are developed years in advance of them actually being adopted and enforced. The 2016 edition of NFPA 13: Standard for the Installation of Sprinkler Systems will not be adopted locally until the location’s jurisdiction adopts the 2018 edition of the International Building Code or 2018 edition of NFPA 101: Life Safety Code.

There are some authorities, however, that adopt the most current edition of the standards. Most notably, the U.S. Department of Defense typically applies the most recent edition of the NFPA standards to projects. It may also be advantageous from a risk management perspective to apply the most recent edition of a code to a project. This is because there may be areas addressed in the most recent code that aren’t addressed in previous editions that can influence a design.

The most recent edition of a standard is typically considered to contain the latest and best thought on the subject. However, if there are changes from the actual standard that are being enforced on a project, it is recommended that any deviation from the adopted standard be reviewed with the authority having jurisdiction (AHJ) during the design process.

For product manufacturers and installers, knowing what is coming down the road can also help prepare for implementing the new code requirements. The knowledge also can be used to impact product design or help develop training material for employees who design and install systems.

There are a number of significant changes in the 2016 edition of NFPA 13 that will be evaluated in addition to the new organization of the 2019 edition.

Metric conversions: During the development of the 2016 edition of NFPA 13, the association’s correlating committee established a task group to review the metric conversions within the standard and make recommendations for potential revisions to enhance usability outside of the United States. Previous editions of the standard used an exact conversion between U.S. customary units and metric units. Where it was deemed appropriate by the task group and technical committees, nominal metric equivalents or approximate conversions have been provided. The standard explicitly notes in Section 1.6.3 that it is acceptable to use the exact conversion or the conversion stated in the standard even though they may not be the same. Section A.1.6.3 of Annex A provides explanatory information and examples of conversions.

Storage commodity classification: The criteria for defining Class IV commodities has been expanded to include criteria for cartoned versus exposed products. Class IV commodities can also include limited amounts of Class A plastics (expanded and unexpanded). Figures have been added that note the allowable mixtures (on a percentage by volume basis) of expanded and unexpanded Group A plastics for purposes of defining the commodity classification. (Figures [a] and [b])

Cellulosics, natural rubber, and nylon have been reclassified from Group B to Group A plastics. PVF (polyvinyl fluoride) has been reclassified from a Group C plastic to a Group A plastic.

Treatment of extension fittings: A definition of extension fittings and criteria for their use have been added to the standard. An extension fitting is an adapter that is used to adjust the final fit where sprinklers are installed in a finished ceiling or wall. Previous editions of the standard do not address extension fittings.

A new Section 6.4.8 has been added. Extension fittings are allowed to be used with sprinklers having a K factor of 8 or less in light or ordinary hazard occupancies only. A single extension fitting having a maximum length of 2 in. is allowed and is not required to be included in the hydraulic calculations.

Extension fittings longer than 2 in. are allowed if they are specifically listed and are included in the hydraulic calculations.

Air venting: A requirement has been added that each wet-pipe system using metallic pipe be provided with a vent. The vent is required to be located near a high point in the system to allow air to be removed from the system (Sections 7.1.5 and 8.16.6). The vent can consist of a manual valve, an automatic valve, or other approved means. The intent of the requirement is to provide a means for removing trapped oxygen that could fuel corrosion, and that the valve be operated after each drain-and-fill event. Only one vent is required per system. There isn’t an intent that all air that may be trapped in the system be vented. The provision of more than one vent is at the designer’s discretion.

Galvanized pipe in dry systems: The requirement that galvanized steel pipe be used in dry and preaction systems was removed from the standard. The technical committee removed the requirement because there have been instances where galvanized pipe has corroded as quickly as nongalvanized steel pipe.

Sprinklers under skylights: A clarifying section (Section has been added to the standard regarding the placement of sprinklers under skylights. This section notes that for the purpose of determining the distance of a sprinkler to the ceiling, the ceiling plane shall be measured to the ceiling as if the skylight were not present. This is applicable to skylights that are less than 32 sq ft in area.

It is also important to note that the 2013 and 2016 editions allow omission of sprinklers from skylights that are less than 32 sq ft in area when they are located greater than 10 ft from another unprotected skylight or ceiling pocket.

Sprinklers under obstructions: Most designers and installers are aware that obstructions wider than 4 ft require sprinkler protection below the obstruction. Two new criteria have been added to the standard addressing these obstructions. One requirement mandates that sprinklers be installed no more than 12 in. from the bottom of the obstruction and is applicable to all types of sprinklers with the exception of residential sprinklers, which are to be installed in accordance with their listed distance below ceilings (Sections,,, and The other requirement addresses sprinklers below round ducts that are creating an obstruction, stating that the sprinklers be intermediate-level/rack-storage type or otherwise shielded from the discharge of overhead sprinklers. This requirement is applicable to pendant and upright sprinklers as well as residential sprinklers (Sections,, and

Clearance to storage: An allowance has been added to the standard to permit wall-mounted shelving not located directly below a sprinkler to extend above a plane that is 18 in. below the sprinklers. The standard does not limit the height of wall-mounted shelving that is not directly below a sprinkler. Wall-mounted shelves could be installed up to the ceiling (Section

Sidewall sprinklers in soffits and above cabinets: The limitation that sidewall sprinklers be located within 4 in. of the bottom of a soffit to avoid sprinklers below the soffit has been removed. The sidewall sprinkler just needs to be located on the soffit within the spacing limitations from the ceiling (Section

Criteria for sidewall sprinkler installation in soffits above cabinets were previously only applicable to soffits and cabinets in residential areas and occupancies. Limiting the use of these rules in other occupancies has been deleted (Section

Minimum distance from obstructions: The “three times rule” to limit the impact of obstructions on water distribution requires that standard sprinklers be located away from the obstruction at a distance equaling at least three times the width of the obstruction. The standard notes a maximum clearance of 24 in. from an obstruction. There has been clarifying criteria added to the rule for standard pendant and upright spray sprinklers and sidewall standard spray sprinklers, noting that the maximum clear distance of 24 in. is not applicable when considering vertical obstructions, such as columns (Sections and

The “four times rule,” which is applicable to extended coverage and residential sprinklers, has also been revised to note that the maximum clear distance rule is not applicable to vertical obstructions, such as columns.

Small openings and concealed spaces: 

A new definition for small openings has been added to the standard. A small opening is defined as an opening in a ceiling or a construction feature of a concealed space that allows limited amounts of heat to enter the concealed space (Section 3.3.21). The annex section notes that a 4×2-ft diffuser would meet the definition of a small opening. If the length of the opening is greater than 4 ft, the width of the opening is limited to 8 in.

Small openings come into play when determining whether a concealed space needs to be sprinkler-protected. For example, noncombustible or limited-combustible concealed spaces that do not have access are not required to be sprinkler-protected. A ceiling forming the bottom of the concealed space is allowed to have “small openings” and is still not required to be sprinkler-protected (Section

Bathroom sprinkler exception: Section has been revised to make the sprinkler exception for bathrooms that are smaller than 55 sq ft and have limited combustible or noncombustible walls, applicable to all dwelling units. In the previous edition of the code, this exception was only applicable to dwelling units in hotels and motels.

Cloud ceilings: A new section in the standard has been added that allows cloud ceilings to be installed without sprinklers above the cloud ceilings. To take advantage of the allowances, an analysis considering the elevation of the cloud ceilings, the maximum dimension of the elements of the cloud ceiling, and the gaps between cloud elements must be performed. If specific parameters are met, sprinklers can be eliminated above the cloud ceiling. Sprinkler-coverage limitations are also driven by the size of cloud elements and the space between elements relative to the cloud ceiling height. There are also parameters on types of sprinklers that are allowed as well as the surface of the clouds (smooth ceiling construction). These requirements and allowances are located in Section 8.15.24 of the standard.

The criteria in this section is intended to apply to a cloud ceiling that has been installed throughout a room. This section would not allow the space above obstructions suspended from a ceiling to not be sprinklered. These obstructions are often referred to as clouds by interior designers, but due to the large openings around the clouds, would not fall within the allowances of Section 8.15.24. The maximum space between clouds or the edge of a cloud and the wall of a room is 1 in. of gap per foot of vertical height of the cloud ceiling from the floor. Therefore, a cloud ceiling that is 10 ft above the floor could have a maximum of 10 in. between clouds or between the edge of the cloud and the wall.

The minimum dimension of the individual cloud elements and the actual gap relative to the height of the ceiling is used to determine the sprinkler coverage from Table of the NFPA 13 standard. If the actual gap is larger than 1 in./ft of ceiling height, the omission of sprinklers above the cloud ceiling is not allowed.

Sprinklers in revolving doors: A code section was added to explicitly note that sprinklers are not required in revolving doors (Section 8.15.25).

Sprinkler-protected glazing: Criteria has been added to address the use of sprinklers and glazing when used as an alternative to a fire-rated wall or window protection (Section 8.15.26).

Inside hose stream allowance: For combination sprinkler/standpipe systems (Class I or III) in buildings that are fully sprinkler-protected, an inside hose stream demand is not required to be included in the hydraulic calculations (Section

Storage: Numerous clarifications in the requirements for storage occupancies have been made in chapters 12 through 20. Those dealing with storage occupancies should thoroughly review these chapters.

Air-leakage testing of modifications to existing systems: A new section has been added to Chapter 25 addressing air-leakage testing of modifications to existing dry pipe and double-interlock preaction systems. Two options for testing are provided in Section One method involves a 2-hour pressure test and the other allows a 4-hour test under normal operating pressure.

Future revisions to the standard

The development of the 2019 edition of NFPA 13 is well underway. The first-draft meetings of the technical committees were held last year. The public comment closing date is May 10, 2017, and committees will be meeting in June to act on the public comments.

Leading up to the development of the 2019 edition, the technical correlating committee established a reorganization task group. The work of the task group resulted in a recommendation that the standard be reorganized. The goals of the reorganization include:

  • Provide a more logical sequence for the presentation of information and requirements for users not intimate with the current format.
  • Address current redundancies and gaps in requirements for protection of storage. Address dispersal of requirements throughout the standard that deal with a common subject.
  • Reorganize Chapter 8.

The recommendations of the task group have been accepted, and the 2019 edition of NFPA 13 will be reorganized as noted below.

Chapters 1 and 2 will continue to address the administrative requirements and referenced publications with no reorganizational changes.

Chapter 3, which addresses definitions, will be reorganized. The definitions currently are divided into subcategories within the chapter, and items are alphabetized within the subcategory. If a user is not aware of the subcategory where a definition would reside, it can be difficult to find. All of the definitions will be in alphabetical order and the subcategories will be deleted.

Chapter 4 will contain the general requirements for sprinkler systems. These requirements are currently scattered amongst Chapters 5, 8, and 23.

Chapter 5 will contain the requirements for water supplies that currently reside in Chapter 24.

Chapter 6 will contain the requirements for underground piping currently in Chapter 10.

Chapter 7 will contain the requirements for system components and hardware.

Chapter 8 will address system types and requirements. The current Chapter 8 is being split into multiple chapters, and the current requirements in Chapter 7 will be moved to the new Chapter 8.

Chapter 9 will include sprinkler-location requirements that are currently in Chapter 8. Allowances for sprinkler omissions and protection for special situations will be located in the new Chapter 9. Criteria for the protection area per sprinkler and spacing also will be located in Chapter 9.

Chapters 10 through 15 will contain the design and installation criteria for the various types of sprinklers that are currently all located within Chapter 8.

Chapters 16 and 17 will address piping valves and appurtenances and hanging and support requirements.

Chapter 18 will address seismic design requirements, and Chapter 19 will provide design and calculation requirements.

Chapter 20 will provide general requirements for storage, and chapters 21 through 25 will address specific storage requirements and in-rack sprinkler requirements.

Chapter 26 will address special-occupancy requirements. System testing will be addressed in Chapter 27. Chapter 28 will address modifications to existing systems, and 29 will address marine systems. Chapter 30 will address system inspection, testing, and maintenance.

There will also be technical changes to the standard, as there are in every revision cycle. The committees have tried to limit significant technical changes during this cycle due to the major reorganization.

This article highlights many of the changes in the 2016 edition of NFPA 13. These identified changes are ones that are deemed to have a more critical impact on the standard and should not be considered inclusive of all changes.

The 2019 edition should be much improved from a usability perspective. As can be seen by the organization, the intent is to be able to apply the document as one would go through the steps of designing or reviewing a system. As always, the standards are in a continual state of change to allow for improvement and acceptance of new technologies and approaches.

Raymond A. Grill is a principal with Arup. He is chair of the of the NFPA 13 Technical Committee on Sprinkler System Installation Criteria and serves on the Technical Committee on Building Services and Fire Protection Equipment for NFPA 101/5000. He is a member of the Consulting-Specifying Engineer editorial advisory board.