Construction Concerns: Parapeted Firewalls

Article and photos by Gregory Havel
 
Fire-rated walls and their parapets are designed with a fire-resistance rating and structural stability and to separate buildings or parts of buildings to prevent the spread of fire. The walls are made of fire-resistive or non-combustible materials and are supposed to extend from the lowest level of the building through the roof, with a parapet on top (photo 1). Building codes allow some types of fire-rated walls to end at the underside of the roof deck or of a fire-resistive roof-ceiling assembly.

 

(1)

(2)

The firewall parapet in photo 1 appears to be built of masonry; to extend beyond the face of the perpendicular walls; and to extend above the roof of the tallest building. The firewall parapet in photo 2 separates two buildings that were built close to the property line. National Fire Protection Association (NFPA) Standard 221 Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls (2009) outlines the requirements in Articles 6.6 and 7.2.
 
The same requirements are outlined in NFPA Standard 5000, Building Construction and Safety Code (2009), in Article 7.3.
 
According to these codes, parapets on firewalls may be omitted if certain conditions are met. Conditions listed in NFPA 5000, Article 37.1.3, permit firewalls to be built without parapets extending through the roof:
  • In locations where unprotected openings are permitted
  • In locations where the roof has a slope greater than 4:12 up from the back wall of the building, and when the roof covering has a Class A rating
  • In locations where the exterior wall of the building is located 20 feet (6.1 m) or more from the property line, an alley, or a public way at least 20 feet (6.1 m) wide
  • In buildings completely protected by an automatic fire sprinkler system that complies with NFPA Standard 13, Standard for the Installation of Sprinkler Systems
  • In buildings where the roof is constructed of noncombustible or limited-combustible materials and the joint between the wall and the roof is sealed with an approved fire-stop system
  • In buildings with combustible roofs (Types III, IV, and V) where all of the conditions listed in NFPA 5000, Article 37.1.3.1(6), are met
 As a result, fewer parapets are included as parts of firewalls in new construction than in the past.
 
A note in our preincident plan for a structure regarding firewalls with parapets and the integrity of these firewalls between the roof and the foundation can give us an advantage at a major incident. The presence of a parapet on a firewall can be an easy reminder of the location of built-in defense lines within the building and can assist us in containing a fire or other incident to the area of its origin. 

We must remember, however, that the presence of a parapet does not always indicate a firewall below. Sometimes the firewall was removed after an automatic fire sprinkler system was installed; the firewall was breached for doorways, conveyors, or unprotected ducts; or the parapet functions only as an expansion joint in the roof membrane and not as a firewall.

Download this article as a PDF HERE.

 
Gregory Havel is a member of the Town of Burlington (WI) Fire Department; retired deputy chief and training officer; and a 30-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 30 years of experience in facilities management and building construction; and has presented classes at FDIC.

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