American Fire Sprinkler Association
12750 Merit Dr., Suite 350 * Dallas TX 75251
Ph: (214) 349-5965 Fax: (214) 276-0908
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TECHNICAL UPDATE
FEBRUARY 10, 2010
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We have an existing building with an exterior overhang that is combustible
construction. It has a ceiling so is considered a concealed combustible space.
It is only 47 inches wide. The exterior wall is open along the underside of
the roof so the overhang is open to the interior of the building. The building
construction above the interior ceiling is non-combustible. There are no
exterior combustibles beneath the overhang. Is the overhang required to be
sprinkler protected?
We have reviewed the 2007 and 2010 editions of NFPA 13 as the applicable
standard. Our informal interpretation is that protection is required within the
concealed space unless you meet one of the exceptions.
There are two aspects to the overhang since it is enclosed. One is protection
beneath it (per 13:8.15.7) and the other is protection within it (per
13:8.15.1). Protection is not required beneath it since it is less than 4 ft
wide and no combustible are stored or handled beneath it (13:8.15.7.1 and
8.15.7.5). Concealed combustibles spaces must be protected or meet one of
several exceptions in section 8.15.1 with the most prevalent being to fill the
space with insulation. There is a new allowance that explicitly addresses
overhangs such as yours in the 2010 edition of NFPA 13. Section 8.15.1.2.18
allows omission of sprinklers within exterior overhangs of combustible
construction when all the following requirements are met:
A. Overhang is not over 4 ft wide
B. It is separated from the interior of the building with
non-combustible walls with no unprotected openings. The wall itself is not
required to be fire rated.
C. The interior of the overhang must be divided with draftstops into
volumes no greater than 160 cu. ft.
Although this is a new item in the 2010 edition it can be applied under the
equivalency clause (1.5) since it is a clarification of what to do with
concealed spaces on the exterior of the building.
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Technical Update is prepared by the Technical Services Dept. of the AFSA: Vice
President of Engineering and Technical Services Roland Huggins, a PE registered
in fire protection engineering; Phill Brown, a NICET IV certified automatic
sprinkler technician and NFPA Certified Fire Protection Specialist (CFPS) and
Tom Wellen, a degreed fire protection engineering technologist. This is
provided with the understanding that the AFSA assumes no liability for this
opinion or actions taken on it and they are not to be considered the official
position of the NFPA or its technical committees.
Copyright © 2010, American Fire Sprinkler Association. All Rights Reserved
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