10/15/2026
Most people don’t think of flame spread on the exterior of a building. But when using foamed plastics on exterior wall cavities, not only is it a concern, it's a code requirement.
When it’s applied over foam on the outside of a building, our DC315 can be part of a tested assembly designed to help prevent flames from travelling up the exterior. Here's how:
Interior Assembly
1 - Gypsum board: 5/8"" Type X gypsum wallboard
2 - Insulation: 2"" (R-14) of medium density Closed Cell spray applied polyurethane foam
Base Wall
3 - Steel Stud Wall
Exterior Assembly
4 - Wallboard: 1/2"" Exterior gypsum wallboard
5 - Insulation: 3 1/2"" (R-24) of medium density Closed Cell spray applied polyurethane foam
6 - Intumescent Coating: 18 mils DC315 Fire protective coating & Sherwin Sher Cryl Protective topcoat
7 - Cladding: virtually any Cladding, including Aluminum
8 - Cladding Attachment: 4"" deep horizontal Z-girts, 1"" 'Hat Channel'
That means certain projects may be able to achieve the required fire protection without relying on traditional masonry cladding.
DC315 isn’t just about covering foam, it can be part of a much bigger fire-protection strategy.
Assemblies must follow the configurations in ESL-1286.
