Issue Description:
The FBC now reflects changes made in the IBC to minimum air impermeable (ISO/EPS board) insulation requirements for unvented roof assemblies, which is typical for flat roofs. In prior code cycles, we have allowed the GC to omit ISO/EPS board on the top of the roof deck if the trusses could be sloped to achieve the required drainage. While the sloping of the trusses is still a preferred approach, we must maintain a minimum of R-5 ISO board on the top of the roof deck in accordance with the referenced code sections. This requirement is to help prevent condensation from forming within the roof cavity.
Proposed Resolution:
Ensure that all applicable roof sections and keynotes call for a minimum of R-5 air impermeable (ISO/EPS) insulation on the top side of the roof deck, with the balance of air permeable (batts/blankets) insulation installed directly to the underside of the roof decking.
Commentary:
N/A
Additional Considerations: