New IBC Rules for Insulation in Unvented Enclosed Roof Framing Assemblies

摘要

These new requirements in section 1203.3 place restrictions on roof assemblies with insulation below structural roof decks in unvented spaces, as the code recognizes the risk of condensation on interior surfaces. In many cases, simple rearrangement of insulation to the top of the structural deck will satisfy these requirements. When insulation must be placed in an unvented attic, designers would have to provide supporting analysis demonstrating materials inside the building enclosure remain above the dewpoint. For any arrangement of roofing and insulation materials unfamiliar to the designer, computer modeling and further consulting is a prudent choice regardless of new requirements in section 1203.3.