R316.5.7 Foam Backer Board
The thermal barrier specified in Section R316.4 is not required where siding backer board foam plastic insulation has a thickness of not more than 0.5 inch (12.7 mm) and a potential heat of not more than 2000 Btu per square foot (22 720 kJ/m2) when tested in accordance with NFPA 259 and it complies with one or more of the following:
- The foam plastic insulation is separated from the interior of the building by not less than 2 inches (51 mm) of mineral fiber insulation.
- The foam plastic insulation is installed over existing exterior wall finish in conjunction with re-siding.
- The foam plastic insulation has been tested in accordance with Section R316.6.