By Gregory Havel
Fire containment is still a basic concept in fire protection and fire suppression. These fire containment features provide us with structural features that will limit the spread of fire and combustion products and allow firefighters to determine the proper places from which to prevent the spread of fire into uninvolved parts of the building.
As most modern buildings do not exhibit their fire containment features as plainly as 19th century mills, we must use preincident planning to discover where these features are located and what resources we will need to defend them in case of a fire. Whether we are performing company-level fire inspections, follow-up inspections, planning a review in a fire prevention bureau, or consulting with building owners and architects on building and fire code requirements for a new or renovated building, we must keep in mind that the fire containment features we are reviewing have been developed over centuries of bad experience. They are intended to ensure that the occupants of the building will be able to escape a fire and that firefighters will be able to extinguish a fire before it grows beyond the capabilities of their resources.
Automatic fire sprinklers have been acknowledged as an excellent way to contain fires until the arrival of the fire department; this is one of the points included in the National Board of Fire Underwriters specification for mill construction in 1880. Photo 1 shows the air piping manifold for the dry pipe sprinklers in a mill building, installed around 1890, that is still in service and maintained according to National Fire Protection Association (NFPA) 13, Standard for the Installation of Sprinkler Systems, and NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems.
(1) Photos by author.
These systems are so effective that municipal officials and building codes (see NFPA 5000, Building Construction and Safety Code®,2015 edition, Section 7.6, and proceeding sections) offer the following incentives for buildings to be equipped with sprinklers:
- Increased spacing between fire hydrants.
- Reduction in fire flow requirements, and smaller water mains.
- Decreased street width.
- Increased distance between the building and public access streets.
Building codes offer the following additional incentives for the installation of sprinkler systems:
- Increased building height and floor areas when compared to unsprinklered buildings.
- Increased travel distances to exits and exit stairways.
- Decreased exit widths.
- Changes in the construction requirements for corridor and tenant separation walls.
- Changes in the flame spread requirements for wall and ceiling finishes.
- Increased distances between draft-stopping in attics and cocklofts.
The following specifications are from NFPA 5000, 2015 edition, Table 7.4.1 for Type V (wood frame) construction:
- Maximum building height, one-hour-rated construction: 70 feet sprinklered; 50 feet non-sprinklered.
- Maximum building height, 0-hour-rated construction: 60 feet sprinklered; 40 feet non-sprinklered.
Following are two examples from Table 7.4.1 for Type V (wood frame) construction:
- Assembly occupancy: <= 300 persons:
o One-hour-rated construction: four stories sprinklered, three stories non-sprinklered, and 11,500 square feet maximum per floor.
o Zero-hour-rated construction: two stories sprinklered, one story non-sprinklered, and 5,500 square feet maximum per floor.
- Business occupancy:
o One-hour-rated construction: four stories sprinklered, three stories non-sprinklered, and 18,000 square feet maximum per floor.
o Zero-hour-rated construction: three stories sprinklered, two stories non-sprinklered, and 9,000 square feet maximum per floor.
From the data above, note that one-hour-rated construction is permitted greater height than zero-hour-rated construction, sprinklered construction is permitted a greater number of stories than non-sprinklered construction, and sprinklered construction is permitted twice the area per floor than non-sprinklered construction.
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The same pattern holds for other occupancy types and other construction types. For some occupancy types in noncombustible (Type II) or fire-resistive (Type I) construction with sprinklers, the number of floors permitted as well as the maximum area per floor is unlimited; it is also limited without sprinklers.
(Note that the International Building Code makes similar adjustments to height, area, and travel distance to exits.)
When a municipal or state building official issues a Certificate of Occupancy for a completed building equipped with an automatic fire sprinkler system which, by the building codes, can be higher, be greater in area, and have greater travel distance to its exits than a non-sprinklered building, it is issuing the certificate assuming that the building will be occupied with the sprinkler system in service.
We in the fire service must strongly suggest (and insist, if necessary) to building owners and tenants that sprinkler system maintenance work and remodeling that requires shutting off the sprinkler system and must be done on days and at times when the building is not occupied. Photo 2 shows two wall postindicator valves, one indicating that the sprinkler system control valve is “OPEN” and the other that it is “SHUT.”
(2)
An occupied, sprinklered building with the sprinkler system inactivated is a building and fire code violation; it is likely to be too high, too large in area, and have its exits too far apart to comply with the code requirements for a non-sprinklered building. These code requirements are not arbitrary, but they have been developed over the past 100 years in reaction to fires where large numbers of people lost their lives.
As Alan Brunacini (Chief, Phoenix Fire Department, retired) states so well:
“The punch line of my lesson is that the structural fire we fight is the result of how that place meets or does not meet the codes and the behaviors of the people connected to that fire event. A critical part of an accurate fireground situation evaluation must be a basic understanding and awareness of the construction / use / behavior factors of that occupancy, because the presence / absence of those code-related factors will define and allow the fire that can occur in that place….ultimately burning buildings and their occupants live or die according to code, and it is very difficult for us to outperform that reality.”
– From “Rules of Engagement: Old Mutt, New Tricks”, by Alan Brunacini. Fire Engineering, June 2008, page 148.
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Gregory Havel is a member of the Town of Burlington (WI) Fire Department; retired deputy chief and training officer; and a 35-year veteran of the fire service. He is a Wisconsin-certified fire instructor II, fire officer II, and fire inspector; an adjunct instructor in fire service programs at Gateway Technical College; and safety director for Scherrer Construction Co., Inc. Havel has a bachelor’s degree from St. Norbert College; has more than 35 years of experience in facilities management and building construction; and has presented classes at FDIC.
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