Photo Source: Summerhill

9.10.17.10. (1) Except as provided in Sentences (2), foamed plastics that form part of a wall or ceiling assembly in combustible construction shall be protected from adjacent space in the building, other than adjacent concealed spaces within attic or roof spaces, crawl spaces, wall assemblies, by

a) one of the interior finishes described in Subsections 9.29.4 to 9.29.9.,

b) sheet metal mechanically fastened to the supporting assembly independent of the insulation and having a thickness of not less than 0.38 mm and a melting point not below 650°C, provided the building does not contain a Group C major occupancy, or

c) any thermal barrier that meets the requirements of Clause 3.1.5.15.(2)(e).