Purpose: There is a conflict between the Energy Code and the International Residential Code. This clarifies that in residential buildings stud cavities and floor systems can be used as part of an air return plenum.
A. An exception to Section R403.3.5 shall be added as follows:
Exception: Building-framing cavities used as ducts or plenums shall comply with Section M1601.1.1 of the International Residential Code
(2020-10, 12-23-2020)