sprinklernotes
Spray Foam Insulation in Combustible Concealed Spaces.
You asked the following questions: “I have a question concerning the requirement for sprinkler protection in a combustible concealed space. I have an NFPA 13 apartment building with a combustible concealed space above the ceiling on the top floor. The construction is 16-inch open web wood truss with 7 inches of spray foam insulation at the roof deck. Gyp board is attached to the bottom chord of the truss. If the General Contractor were to completely fill the concealed space with a noncombustible insulation (blow-in or batt), would that meet the intent of the section 8.15.1.2.7?” In response to your question, we have reviewed NFPA 13, 2013 edition as the applicable standard. Our informal interpretation is that the spray foam does not impact the application of any of the allowances to omit sprinkler protection. Evaluating the protection of concealed spaces is a two-step process. The first step is to determine if sprinkler protection is required. The second step is to determine if any of the allowances for omitting protection are applicable. The base requirement per section 8.15.1.1 is that concealed spaces of exposed combustible construction greater than 6 inches must be protected. Section 8.15.1.2.1 notes that noncombustible construction must be protected if there is an excessive amount of combustible loading. Technically it says sprinklers are not required with a minimal combustible loading. This is where other materials such as cabling are considered. As discussed in A.8.15.1.2.1 and the Sprinkler Handbook, this means that there can be wiring, and other combustible materials present without a requirement to protect the space. As noted in the annex statement, the point at which protection is required is not defined by NFPA 13 and should be discussed with your local AHJ. The second step is to review section 8.15.1.2 Concealed Spaces Not Requiring Sprinkler Protection and the 18 subsections allowing the omission of sprinklers inside the combustible concealed space. subsection 8.15.1.2.7 allows the omission of sprinkler protection provided the space is filled entirely of noncombustible insulation. NFPA 13, 2013 edition added new subsection 8.15.1.2.7.1 to allow for a 2-in. air gap for concealed spaces filled with noncombustible insulation. In closing, applying Section 8.15.1.2.7 would be an acceptable alternative to providing sprinklers in the combustible concealed space, without regard to the spray insulation application.
