Fire Sprinkler Design Guide [for AHJ's]

This interactive guide, and book, will enable the fire plan reviewer or inspector to quickly answer the most important questions for approval and acceptance of a fire sprinkler system.
  • Does the structure require a fire sprinkler system?
  • Is the occupancy and commodity properly classified?
  • Are plastics properly identified and protected?
  • Does the rack storage need in-rack sprinklers?
  • Will there be any obstructions to the discharge pattern?
  • How are the cloud ceilings protected?
Clicking on the title for each section will take you to a full article on the topic. Before you get started, I recommend you download and print my glossary of "Key Terms  for NFPA 13 Storage". This convenient tool eliminates the need to search multiple pages for clarifications by listing the most used terms and definitions on a single page. 

Reading through the NFPA standards, one consistently comes upon the phrase "sprinklers where required".  However, in order to find where they are, or may be, required, involves some searching through the code book.  

The below is a tool that can be used as a quick guide to what occupancies require fire sprinklers, and where the code can be referenced.

Perhaps you are conducting a fire inspection or survey and you notice that the hazard or commodity classification on the hydraulic calculation plate at the riser seems odd for the actual contents of the structure.  Or, you are sitting down to do a plan review, the occupancy hazard and commodity class is listed. Are these classifications correct based on the use of the structure?

NFPA 13, Standard for the Installation of Sprinkler Systems, chapter five defines occupancy hazard and commodities classifications for the design and installation of sprinkler systems. In book form, this information can sometimes be difficult to recall. This slideshow presentation can be utilized as a reference to quickly review and confirm occupancy and commodity classifications.

To provide effective fire sprinkler protection within a structure, the hazard classification and commodity must be known. For the protection of rack storage, the storage and shelving configuration must be known. Due to the high speed and temperature of burning plastics, they require special consideration.  NFPA 13, Standard for the Installation of Sprinkler Systems, requires all plastics, elastomers, and rubber, to be classified as Group A, Group B, or Group C.

What are the requirements for rack storage? Are in-rack sprinklers required? How can rack storage sprinkler requirements be determined?

Fire protection requirements for rack storage are addressed in NFPA 13, Standard for the Installation of Sprinkler Systems.  
  • Chapter 13, Protection of Miscellaneous and Low-Piled Storage
  • Chapter 14, Protection for Palletized, Solid-Piled, Bin Box, Shelf, or Back-to-Back Shelf Storage of Class I through Class IV Commodities
  • Chapter 15, Protection for Palletized, Solid-Piled, Bin Box, Shelf, or Back-to-Back Shelf Storage of Plastic and Rubber Commodities
  • Chapter 16, Protection of Rack Storage of Class I through Class IV Commodities
  • Chapter 17, Protection of Rack Storage of Plastic and Rubber Commodities

To determine which chapter to go to for fire protection requirements, there are three questions that must be answered:

  1. What is stored?
  2. How is it stored?
  3. How high is it stored?

Important to fire sprinkler effectiveness is sprinkler discharge pattern development. A fire sprinkler system should be designed in a manner that provides full water coverage from the fire sprinkler system. Inherent building construction or design elements can pose potential obstructions to the full coverage or discharge pattern of the sprinkler system.  However, these buildings and elements must still be protected. NFPA 13, Standard for the Installation of Sprinkler Systems, provides sprinkler coverage guidance for these obstructed areas.

To determine the proper application it must first be determined if the construction is obstructed or unobstructed.  Then it must be determined if the obstruction is continuous or noncontinuous.

Cloud ceiling: a suspended ceiling that covers only a portion of a room or space below

These cloud ceilings present unique challenges to fire sprinkler installation. The solution to these challenges are not always easily found clearly in the pages of NFPA 13. However, by applying the obstruction and clearance principles the solution will make itself clear.

What is the "small room" rule?
In conducting plan reviews or fire sprinkler field inspections you may have heard, or seen, the invocation of the “small room" rule. Though not specifically stated in NFPA 13 as the “small room" rule, it is a combination of several code sections within the standard that can be utilized to provide advantages in hydraulic calculations and flexibility in sprinkler spacing.

In 1984 tragedy struck the Great Adventure theme park when 8 teenagers were killed in the Haunted Castle attraction.  The fire, believed (not proven) to have been started by a an individual playing with a lighter, has seen a great deal of controversy, and differing of opinions, through out the years. The resulting code changes created the special amusement requirements in NFPA 101.  

In this video, Jack Fairchild, a certified fire protection specialist with Ballinger A/E, discusses the history and impact of this fire, and guides us through his analysis of the potential effectiveness of fire sprinkler systems, he answers the question, "Would sprinklers have saved these kids?"