March 7, 2016 Insulation on Combustible Upper Surfaces "We have a horizontal concealed space above the ceiling with a wood upper surface and 2x6 in. wood joists. The joists are filled with noncombustible insulation. It is less than 36 inches between the deck and the ceiling. The materials below the joists are limited-combustible or noncombustible. The local AHJ is requiring sprinklers in this space. Am I required to use sprinklers listed for horizontal concealed spaces?" We have reviewed the 2013 edition of NFPA 13 you indicated as the applicable standard. Our informal interpretation is that standard spray sprinklers can be used. Technically, this space does not required protection per Section 8.15.1.2.17. The insulation is an acceptable covering for the wood material negating it being classified as "exposed" combustible construction. In other words, the insulation is considered the outer boundary of the assembly. The local jurisdiction is requiring this space to be protected. This leaves the question as to whether sprinklers should be listed for horizontal spaces per Section 8.15.1.6. This section requires a special listing when three conditions exist. These are: (1) A shallow concealed space less than 36 inches in depth, (2) The space is horizontal (slope not exceeding 2 in 12), and (3) A combustible upper surface.
All three conditions have to be present (just like the attic requirements in Section 8.6.4.1.4). Although the upper deck is wood construction, it is not the upper surface. That would be the insulation. Although it is a different allowance, Section 8.15.1.2.17 explicitly defines insulation as an acceptable covering removing the wood from the evaluation. Since all three conditions do not exist, the requirement to use sprinklers listed for shallow combustible concealed spaces not apply. As such, standard spray sprinklers can be used to protect this shallow concealed space. 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 PE registered in fire protection engineering. 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 2016, American Fire Sprinkler Association. All Rights Reserved Training Calendar AFSA Beginning Fire Sprinkler System Planning School 2016 Schedule April 4 - 15, 2016 May 16 - 27, 2016 July 18 - 29, 2016 Oct. 3 - 14, 2016 For more info, call: 214-349-5965 ext. 132
