April 3, 2026
Daily Code Talk #95
IMC 602.3.7–602.4 addresses materials and flood risks in plenums. Exposed materials must meet strict flame/spread and smoke limits, and plenums in flood zones must prevent water intrusion or resist hydrostatic forces.
April 3, 2026
Daily Code Talk #94
IMC 602 Part 3- Once materials or devices are exposed in the airstream, the question is no longer “can it fit above the ceiling?” It becomes “is it noncombustible, enclosed, or specifically listed for plenum use?”
April 2, 2026
Daily Code Talk #93
IMC 602.2 is where plenum design shifts from “where it is allowed” to “what it is made of.” For plan review, this is where exposed materials, gypsum-board plenums, and framing-cavity plenums often fail because the drawings show the space, but not the compliance path.
April 1, 2026
Daily Code Talk #92
IMC 602.1 is where plenum compliance starts. The review issue is usually not whether air is moving through the space. It is whether the drawings clearly treat that space as a plenum and apply the right location, fire-area, and equipment restrictions.
