(See Note A-3.1.4.2.)
(1)
Except as permitted in Sentence (2), foamed plastics that form part of a wall or ceiling assembly in combustible construction shall be protected from adjacent spaces in the building, other than adjacent concealed spaces within attic or roof spaces, crawl spaces, and wall and ceiling assemblies,
(a)
by one of the interior finishes described in Subsections 9.29.4. to 9.29.9.,
(b)
provided the building does not contain a Group A, Group B or Group C major occupancy, by sheet metal
(i)
mechanically fastened to the supporting assembly independent of the insulation,
(ii)
not less than 0.38 mm thick, and
(iii)
with a melting point not below 650°C, or
(c)
any thermal barrier that meets the requirements of Sentence 3.1.5.15.(2). (See Note A-3.1.4.2.(1)(c)) (See Note A-3.1.4.2.(1))
(1.1)
The flame-spread rating on any exposed surface of combustible insulation, or any surface that would be exposed by cutting through it in any direction, shall be not more than 500.
(2)
A walk-in cooler or freezer consisting of factory-assembled wall, floor or ceiling panels containing foamed plastics is permitted to be used in a building permitted to be of combustible construction, provided the panels
(a)
are protected on both sides by sheet metal not less than 0.38 mm thick having a melting point not less than 650°C,
(b)
do not contain an air space, and
(c)
when a sample panel with an assembled joint typical of field installation is subjected to the applicable test described n Subsection 3.1.12., have a flame-spread rating not more than that permitted for the space in which they are located, the space that they bound, as applicable. (See Note [b-3.1.4.2.-appx|A-3.1.4.2.] and 3.1.5.7.(3))
(3)
The flame-spread rating of doors containing foamed plastics shall comply with Sentences 3.1.13.2.(1) to (3).