R316.5.2

Section R316.5.2 is titled 'Roofing' and covers requirements for foam plastics. The allowance for exemption from another section of this code which requires a thermal barrier between foam plastic insulation and the interior of a dwelling when specific listed materials are used as part of a roofing assembly, and the allowance for an exemption to another section of this code which requires a maximum smoke-developed index is established. The purpose of this section is to allow for wood planks or wood structural panels to be an alternative to a thermal barrier without requiring it to be tested, as well as allowing for greater maximum smoke-developed index foam plastics on roofs because rising smoke from a roof is less likely to create a smoke inhalation hazard to the occupants.

The model shows a partial flat roof with a cutaway section of foam plastic insulation installed above the wood structural panel sheathing.