The exterior wall assembly shall be tested in accordance with and comply with the acceptance criteria of NFPA 285.
- One-story buildings complying with Section 2603.4.1.4.
- Wall assemblies where the foam plastic insulation is covered on each face by not less than 1-inch (25 mm) thickness of masonry or concrete and meeting one of the following:
- There is no airspace between the insulation and the concrete or masonry.
- The insulation has a flame spread index of not more than 25 as determined in accordance with ASTM E84 or UL 723 and the maximum airspace between the insulation and the concrete or masonry is not more than 1 inch (25 mm).