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Clarification to NFPA 220 Standard Types of Building Construction

Question asked by ericsuh on Aug 30, 2019
Latest reply on Sep 10, 2019 by rfdacm02

“Quote”

Clause 4.1.6.3 The material has a structural base of a noncombustible material with a surfacing not exceeding a thickness of 1/8 in. (3.2 mm) where the surfacing exhibits a flame spread index not greater than 50 when tested in accordance with ASTM E 84, Standard Test Method for Surface Burning Characteristics of Building Materials or ANSI/UL 723, Standard for Test for Surface Burning Characteristics of Building Materials. [5000:7.1.4.2.1]

(Unquote)

 

Question regarding the meaning of the words, Structural base of noncombustible material:

  • Does this mean materials used for structure (such as; steel, concrete or other materials which is used for building structure) with above mentioned surface?
  • Or, this means whatever base materials, (ex.; soft rock wool), which is noncombustible under the surface of not over 1/8” thickness?

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