The concept that eventually led to the modern sprinkler system was introduced more than 100 years ago when it was discovered that early mechanical application of water to an incipient fire was the key to reducing property damage in industrial facilities. This concept went through numerous refinements that led to NFPA 13, Standard for the Installation of Sprinkler Systems, with which the fire service has become familiar. Systems installed in accordance with this standard have proven to be invaluable in the control of fire in commercial and residential occupancies. A sprinkler system installed in accordance with NFPA 13 is designed to “provide a reasonable degree of protection for life and property from fire.” Over the years, these systems have permitted the construction of much larger and more hazardous occupancies, boosting production and economies in areas where they would not otherwise be allowed, while at the same time offering minimal chance of a major fire or conflagration.

Findings in the 1973 landmark government report America Burning identified the deplorable loss of life statistics for residential occupancies in the United States. It was estimated at that time that the reported deaths per million population rate in the United States was the worst of any industrialized nation and nearly twice that of second-ranking Canada (51.1 vs. 29.7).1

Given the track record of the NFPA 13 system, the report concluded that offering a simpler, more affordable sprinkler system for use in single-family and multifamily residential occupancies could provide tremendous life-safety benefits. In response, the NFPA Technical Committee on Automatic Sprinklers appointed a subcommittee to develop a standard for the installation of sprinkler systems in one- and two-family dwellings. The basic design objectives for the dwelling sprinkler system were to provide (1) a system that would allow the occupants sufficient time to ensure their survival and (2) a system that would be inexpensive.2

The NFPA estimates that residential sprinkler systems used in conjunction with properly installed and maintained smoke detectors could theoretically reduce the death rate for residential occupancy fires 82 percent. This dramatic potential for saving lives prompted the development of the two “new kids on the block”–the NFPA 13R sprinkler system, designed for residential occupancies up to and including four stories in height, and the NFPA 13D system, designed for installation in one- and two-family dwellings and manufactured homes.

The experience firefighters have gained with sprinkler systems has been limited primarily to those installed under the familiar basic NFPA 13 standard. Impressive statistics associated with the NFPA 13 system back up what firefighters in the field see on a regular basis: that with few exceptions, usually due to improper maintenance or tampering, a fire in a fully sprinklered building will be extinguished or controlled 96 percent of the time. There has never been a “multiple death fire in a completely sprinklered building where the system was operating properly.”3 Is it therefore logical to assume that the newer systems covered by NFPA 13R, Sprinkler Systems in Residential Occupan- cies Up to and Including Four Stories in Height–1996, and 13D, Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes–1996, will perform in a similar manner? They may not, as the following scenarios illustrate.


The Fairfax County (VA) Public Safety Communica-tions Center received a call reporting a fire in the Essex House Square garden apartment complex in the Franconia area of the county at 8:52 a.m. on June 24, 1993. First-arriving units encountered a structure of Type V, wood-frame construction with heavy fire involving the attic space, roof, and exterior. By 9:12 a.m. (20 minutes later), the roof had begun to collapse, and all occupants and fire department personnel had been evacuated from the building. In all, the fire destroyed eight apartments, totaling more than 10,000 square feet. It was determined that the fire was started by a malfunctioning propane grill on the patio of a ground-level apartment. It then extended up the exterior to the attic, which soon collapsed onto the top-floor apartments, consuming them in the process and extending to adjacent units.4 Miraculously, no one was killed or injured. Would the outcome of this fire have been any different if the building had been protected by a residential sprinkler system?

A similar fire in the Old Buckingham Station apartment complex in Chesterfield County, Virginia, on May 19, 1995, destroyed the wood-frame clubhouse structure and 58 apartment units, causing approximately $3 million damage. A T-shirt draped over a light attached to the open breezeway outside one of the units was thought to be the cause of the fire. The progression of this fire was similar to the one in Fairfax County. The fire spread up the exterior of the building (most likely by way of the combustible vinyl siding) and entered the open attic space. It then collapsed the upper roof assembly down around the lower units, allowing the fire to spread. Again, fortunately, no one was killed or injured. What was different about this fire was that the complex was “protected” by an approved residential sprinkler system. It is reported that the onslaught of fire from above melted the plastic sprinkler piping, disabling the system and allowing the uncontrolled fire to spread.5

Is this what firefighters should expect when encountering a fire in this type of building when a sprinkler system is present? What could possibly allow this to happen to a building that was “protected” by a system installed in accordance with current standards? Before attempting to answer these questions, let`s look at the differences in the systems.


The first thing to consider is that there is a difference in the basic objectives established for systems installed under the NFPA 13, 13R, and 13D standards. The main objective of the NFPA 13 system is property protection and life safety. The 13R and 13D systems, on the other hand, are designed with a “high, but not absolute, level of life safety and a lesser level of property protection” as their operational criteria.6 The 13R and 13D systems mirror the basic fireground objectives of life safety as a primary objective and property conservation as a secondary consideration. For the firefighter, the difference in coverage these systems provide can pose some problems if not looked at more closely.

A sprinkler system installed in accordance with NFPA 13 provides a high level of protection and life safety by providing coverage to virtually all areas of a building, ensuring that nearly all incipient fires will be controlled at the point of origin. Unfortunately, the amount of pipe, heads, fittings, and labor required to install a sprinkler system in accordance with NFPA 13 makes its installation in most residential occupancies cost prohibitive.

The 13R and 13D systems require the use of “residential” sprinkler heads that react to the heat of fire faster, reducing the number of heads and the water supply required. Performance of the 13R system is based on a maximum of four heads activating to control the fire, whereas the 13D systems relies on only two heads. Both systems allow the use of chlorinated polyvinyl chloride (CPVC) and polybutylene pipe. The methods and materials used help ease the economic burden of the systems by reducing the number and cost of required components and the subsequent installation cost. To further reduce the size of the system to make installation of residential sprinklers economically feasible, the specification for sprinkler head coverage under the 13R and 13D standards was made on the statistical basis of where the majority of fatal fires in a dwelling originate. Kitchens, bedrooms, living rooms, dens, lounge areas, and “other known single areas” comprise the most significantly prominent areas of fatal fire origin and account for 81.8 percent. Other locations such as hallway corridors, interior stairways, “structural areas,” lobbies, dining rooms, closets, balconies, porches, “multiple areas,” and areas that remain unclassified make up the remaining 18.2 percent.

These statistics do not reflect where the deaths occur, but where the fires that led to the deaths started.


Basing the areas of sprinkler coverage on these statistics of fatal fire origin led to important omissions under 13R and 13D:

Sprinklers are not required in bathrooms where the area does not exceed 55 square feet, and the walls and ceilings, including behind fixtures, are of noncombustible or limited combustible materials providing a 15-minute thermal barrier (0.6 percent of fatal fire origin).

Sprinklers are not required in clothes closets, linen closets, and pantries within the dwelling units where the area of the space does not exceed 24 square feet and the least dimension does not exceed three feet and the walls and ceiling are surfaced with noncombustible or limited combustible materials as defined by NFPA 220, Standard on Types of Building Construction–1995, (1.2 percent of fatal fire origin).

Sprinklers may be omitted from any porches, balconies, corridors, and stairs that are open and attached (porches account for 1.2 percent of fatal fire origin).

Sprinklers may be omitted from attics, penthouse equipment rooms, crawl spaces, floor/ceiling spaces, elevator shafts, and other concealed spaces not used or intended for living purposes or storage7 (ceiling/roof assemblies account for 0.3 percent of fatal fire origin).

These four areas of allowable sprinkler coverage omission under the 13R and 13D standards account for 3.3 percent of the total area of fatal fire origin. To some, this may be insignificant and justify omissions in coverage. The omission cannot be construed as insignificant for the firefighter or occupant who may need to rely on the successful operation of the system for escape before the fire progresses to untenable conditions or attacks the integrity of the structure.

Surprisingly, potential problems associated with such concessions are reflected in the standard by inclusion of the statement that “the omission of sprinklers from certain areas could result in the development of untenable conditions in adjacent areas.”8 The standard therefore recommends, but does not require, that all areas of the building be sprinklered. These systems are designed to allow an “improved chance for occupants to escape or be evacuated” but not to fully extinguish the fire, as is often assumed.9

The 13D system, for example, requires only a 10-minute stored water supply to allow people to escape when used in conjunction with an adequate local audible alarm installed in accordance with NFPA 72, Standard for National Fire Alarm Code, 1996. The NFPA 13R standard requires a 30-minute water supply, but this and the difference in coverage between the 13R and 13D systems are often negated by the use of two-hour-rated separations between units. The use of two-hour separations allows units to be considered unattached under some building code provisions, allowing the 13D standard to be applied. Both systems “should be capable of maintaining life safety in the room of fire origin for at least 10 minutes.”10 This is all well and good, but how does it affect the firefighter?


Typically, firefighters will encounter a sprinkler system installed in accordance with the 13R or 13D standard after it has activated. If the fire started in one of the statistically prominent areas of the dwelling, then the firefighter will most likely encounter a fully extinguished or small smoldering fire along with some moderate water and smoke damage, not unlike what would be expected in a building protected by a standard NFPA 13 system. But what if the fire was started by a child playing with matches in a closet that was not equipped or required to be protected with a sprinkler head (an area comprising 1.2 percent of fatal fire origin)? Many scenarios can be played out, but given the design-vs.-cost trade-offs inherent with these systems, the fire could possibly overpower the closest sprinkler in an adjacent room. This could allow untenable conditions to develop or the fire to spread to the unprotected ceiling/floor void spaces if the separation has in some way been compromised.

The 13R and 13D systems were tested in laboratory settings simulating actual fire conditions. The test fire is composed of a wood crib and two combustible structures with urethane foam, representing stuffed furniture. Although it is apparent that the test was designed with a sizable margin of overcoverage in mind, it is still a test. Two questions immediately arise when attempting to superimpose the fire test scenarios on hypothetical real-life situations: (1) What can be expected when encountering a fire involving higher than typical fuel loads? (2) What impact will changing the configuration of the fuel load have on system effectiveness?

The NFPA 13R standard states that “a sprinkler system designed and installed according to [the 13R] standard may not be expected to control a fire involving unusually higher than average fuel loads than typical for dwelling units” (10 lb/sq ft).11 Because of this statement alone, firefighters should not expect these systems to extinguish the fire and must be aware of the possibility that a fire of “higher than average fuel load” or unusual configuration might overpower the system or extend to unprotected areas and void spaces within the structure. Sprinkler systems rely on their capability to react to fires that mimic those produced in laboratory settings. The inability of the system to properly combat a fire may be due to variables such as fuel load, fuel configuration, and system maintenance, variables over which only the homeowner has control.

It is equally important to expect that a fire that overpowers a 13R or 13D system may be attacking a structure already compromised by construction trade-offs. A situation such as this should be approached as if the fire had been burning for a longer period of time than estimated. Neither the NFPA 13R nor NFPA 13D standard requires a fire department connection. If a fire were to extend beyond the capabilities of the designed water supply of these systems and no connection were provided, there would be no way to supplement the demand to provide flows necessary to control the fire. Firefighters should recognize some conditions that indicate that the fire is not being controlled by the sprinkler system, such as the following:

Heavy or black smoke showing (not the typical lazy whitish-gray smoke encountered in a fire contained by a sprinkler).

Smoke emanating from concealed spaces such as attics, siding, or between floor areas where large voids may be encountered.

Unusually large volumes of smoke for expected conditions from any part of the building.

Signs of system activation along with high heat buildup on the interior, indicating the system has been overpowered by the fire.


Cobb County, Georgia, which was the model for the installation of sprinklers in the Buckingham Apartment complex in Chesterfield County, Virginia, provides a prime example of how major, approved construction trade-offs are offered to promote installation of residential sprinklers and make them economically feasible. Some examples follow.

Tenant separations reduced from 58-inch Type X fire-rated gypsum wallboard to 12-inch standard wallboard.

Party walls between townhouses reduced from two-hour rating to one-hour rating.

Draft stops in attics required every 3,000 square feet instead of between each unit.

No requirement for one-hour rating of walls and doors to hazardous areas.

Increase of fire department access from 50 feet to 125 feet.

One-hour-rated walls instead of two-hour-rated walls between townhouse units.

Extension of exit travel distance from 20 feet to 35 feet.12

The Cobb County approach is considered a model for residential sprinkler promotion and is the type of installation the firefighter should expect to encounter in a building so equipped.

Compounding the problem for firefighters is the type of structure within which residential sprinkler systems are installed when construction trade-offs are offered. The most prominent addition to the firefighting arena in the past two decades has been the less-than-desirable construction of new homes and apartments that are typically “protected” by 13R and 13D systems. These structures do not possess the sheer mass needed to resist the onslaught of even moderate fire. Construction features present in this type of building, such as truss floors and attic spaces, have become major problems for firefighters in recent years due to the inability of these lightweight components to ward off fire attack.

In DeKalb County, Georgia, fire resulting from a plumber`s propane torch developed in the truss void of an almost completed three-story apartment house. There was no contents load. The sprinkler system was operational but did not activate. A firefighter fell through the second floor into the fire when the truss collapsed. Fortunately, his partner used a hoseline to protect him from the fire until he could be pulled out.l3 A sprinkler system installed under the 13R provision will not control fires in floor trusses; this area of the building may be specifically omitted from coverage.

Phoenix, Arizona, firefighters were ventilating the roof of a large one-story residence. The roof was masonry tile on chipboard on wood trusses. Seventeen minutes into the fire, the roof collapsed. Four firefighters fell into the attic. The sudden failure was due to the fallout of the metal gusset plates. The chipboard remained intact. The firefighters were saved from serious injury or death because they were wearing full protective equipment.14 This type of attic space is not required to have sprinkler protection under the 13D standard.

The term “garden apartment” can conjure up several pictures in the firefighter`s mind–ranging from buildings of older masonry and wood Type III, ordinary construction that have a proven resistance to fire (due to the mass of the construction components) to the now-popular Type V, wood-frame dwellings that pepper our residential landscape today. The vast majority of single-family and rowhouse-type dwellings (townhouses) built in the last decade or so have been constructed in the same lightweight wood-frame fashion. Many firefighters have witnessed what a fire can do to this type of structure and have been amazed at the inability of these structures to resist fire-induced collapse, as seen in the above scenarios.

Given all the factors–the type of construction, the trade-offs given to promote installation, and the built-in compromises of the 13R and 13D systems themselves–it is imperative that today`s firefighter understand how all these factors can interact in a fire situation. Superimposing this on a fire in the middle of the night starting in an unprotected area (such as an open wooden stairwell of a wood-frame garden apartment) should make the firefighter cringe at the life-safety problems that could be encountered.


One final note concerns the maintenance aspect of residential sprinklers. Those involved in the inspection process know that even regular inspection will turn up problems associated with sprinkler system maintenance and readiness. Both the 13R and 13D standards state that the owner is responsible for the condition of a sprinkler system and shall keep the system in normal operating condition. Who will ensure that this is done? The typical standard NFPA 13 system has the built-in advantage of being inspected regularly by the authority having jurisdiction, as outlined in most municipal fire prevention codes. It is not likely that stipulations for residential sprinkler installations will include having the local fire department inspect them regularly. The legal right to privacy enjoyed in the United States and citizens` belief that “my home is my castle” are two factors that will continue to deter the inspection of some residential systems after installation.

So what happens when the homeowner, who may not know better, slaps the third coat of latex paint on his sprinkler heads so they will match the new bedroom ceiling color? What happens when the unwary homeowner drives a nail through a sprinkler pipe and stops the leak by simple shutting off the system? (Monitored systems could help avert this.) History has shown that the typical citizen is apathetic toward fire protection and often has the “It won`t happen to me” attitude–perhaps the greatest reason that our loss-of-life statistics due to fire are so high in this country. One study indicated that 30 percent of the people interviewed perceived no need for a residential sprinkler system.15 The mindset becomes evident to all firefighters who encounter a fire in a house with nonworking smoke detectors. The NFPA estimates that one-third of smoke detectors are nonoperational, due primarily to dead or missing batteries. Unfortunately, the effectiveness of residential sprinkler systems is dependent on properly installed and maintained smoke detectors` warning occupants of the fire quickly enough to provide the window of time needed for escape.

Firefighters commonly lose sight of the fact that dwellings are not designed for fighting fires within; they were designed to be lived in and to possess a reasonable deterrence to fire to allow occupants a chance to escape. For years, the automatic sprinkler system has been an ally to firefighters in combating fire in occupancies of hazardous use and construction. The residential sprinkler has a powerful potential to reduce fatalities, but at this point it is a compromise system that balances construction economies against the cost of full sprinkler coverage.

New elements in the fire service arena–such as hazardous materials, building construction techniques, and the residential sprinkler–present firefighters with new challenges that must be dealt with during every tour of duty. Firefighters will continue to encounter more residential sprinkler systems and will be expected to deal with them appropriately. Like so many other situations encountered, the problems associated with residential sprinklers are in proportion to the firefighter`s inability to recognize the system`s shortcomings. The key to dealing with residential sprinklers is preplanning to understand system objectives, to determine the systems` locations, and to identify what contingencies apply. n


1. America Burning, The Report of The National Commission on Fire Prevention and Control (Washing-ton, D.C.: National Commission on Fire Prevention and Control, 1973), 1.

2. Automatic Sprinkler Systems Handbook, Fourth Edition, Robert Solomon, ed. (Quincy, Mass.: National Fire Protection Association, 1991), 371.

3. Ibid., 4.

4. Fairfax County Fire Prevention Division, Preliminary Event Investigation Report- 6133 Essex House Square (Fairfax County, Va.: Fairfax County Fire and Rescue Department, June 1993).

5. Bowes, Mark and Randolph P. Smith, “Building Code Questioned, Damaged Apartments Exceeded Protection Requirements,” Richmond Times Dispatch, June 1, 1995, A1.

6. NFPA 13R, Standard for the Installation of Sprinkler Systems in Residential Occupancies Up to and Including Four Stories in Height, (Quincy, Mass., National Fire Protection Association, 1996).

7. Ibid.

8. Ibid.

9. Ibid.

10. Automatic Sprinkler Systems Handbook, 381.

11. NFPA 13R.

12. “An Ounce of Prevention” (Washington, D.C.: Federal Emergency Management Agency 1988), 548.

13. Brannigan, Francis L. Building Construction for the Fire Service, Third Edition (Quincy, Mass.: National Fire Protection Association, 1992), 548.

14. Ibid., 554.

15. Cote, Arthur E. Fire Protection Handbook, Seventeenth Edition. National Fire Protection Association, 1992) 5-151.

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The aftermath of the Essex House Square fire. The fire started on the ground floor on the end to the left. Notice the complete destruction of the roof assembly due primarily to exterior fire spread–another area that does not require sprinkler coverage under NFPA 13R. [Photo courtesy of the Fairfax County (VA) Fire and Rescue Department.]

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Building typically “protected” by a residential sprinkler. Many potential fire spread problems are present in this dwelling. Balconies, open stairwells, exterior siding, and chimney enclosures are combustible and excluded from sprinkler coverage under NFPA 13R. The stairwell, if involved in fire, would present a tremendous life safety problem in itself. Construction trade-offs should be expected when sprinklers are present in this type of dwelling. (Photo by author.)

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Understand the advantages to life safety that residential sprinkler systems provide and advocate their installation.

Get involved in the installation process and encourage full system coverage, eliminating the omissions allowed under the standard. Recommend installation of a fire department connection.

Preplan your area to identify which structures are protected by NFPA 13R and 13D sprinkler systems.

Find out exactly what trade-offs were made during construction to promote system installation.

Prepare strategic and tactical plans for dealing with a fire that evades or overpowers the system, concentrating on how construction trade-offs and access variances will affect rescue and stream application.

Assume that the system may not be properly maintained.


Forget that standard NFPA 13 sprinkler systems have been known to operate improperly or inadequately because of many factors out of the firefighter`s control and that the NFPA 13R and 13D systems do not provide the same level of protection.

Assume that the sprinkler system will extinguish the fire.

Let your guard down. Assume collapse can occur even if the sprinkler system has activated. Firefighting water can be lost through broken sprinkler piping.

Ignore the signs of a fire that has overpowered the system–heavy smoke or fire showing or signs of fire in unprotected void spaces such as walls, floor and ceiling assemblies, and attics.

Rely on experience with the standard NFPA 13 system; expect conditions to be different.

Forget that protection priorities for residential systems are the same as fireground priorities: life safety, then property conservation. n

JOSEPH F. WARNER is a career firefighter with the City of Alexandria (VA) Fire Department, where he has served as a firefighter and acting officer for the past 13 years. Previously, he had been a member of the Greater Springfield Volunteer Fire Department in Fairfax County, Virginia, for 10 years. He is an adjunct instructor with the Fairfax County Fire and Rescue Training Academy and is Virginia-state certified as a Firefighter III, Instructor III, and Officer II. Warner has an associate`s degree in fire science administration from Northern Virginia Community College.

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