2603.5.5 Vertical and lateral fire propagation.
BC § 2603.5.5
The exterior wall assembly shall be tested in accordance with and comply with the acceptance criteria of NFPA 285. NFPA 285 design documentation of the tested exterior wall assembly shall be included on the submitted construction documents complying with Section 2601.2.1. Exceptions: 1. One-story buildings complying with Section 2603.4.1.4.
2.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: 2.1. There is no airspace between the insulation and the concrete or masonry. 2.2. The insulation has a flame spread index of not more than 25 as determined in accordance with ASTM E 84 or UL 723 and the maximum airspace between the insulation and the concrete or masonry is not more than 1 inch (25 mm).
