Interpretation #8685
Published September 23, 2022
Original Request
- Code Version
- 2021
- Code
- MECHANIC
- Code Description
- Chapter
- Section
- 602.2.1
- Topic
- PVC drain lines in a plenum AHU closet
Question
Where pvc piping NOT having a 25 flame spread index and a 50 smoke-developed index (when tested in accordance with ASTM E84 or UL 723) is installed within an AHU closet that is constructed as a plenum per FMC 602.2, does covering the pvc piping with a listed 25/50 flame and smoke index insulation bring the pvc into compliance with 602.2.1 regarding materials permitted within plenums?
Answer Published 09/23/2022 at 10:33 AM
Section 602.2.1outlines the requirements for materials within plenums, and also provides 6 exceptions. In reference to your question, as it applies to wrapping/ protecting the PVC piping, exception 5, and specifically 5.3 provide a resolution. Exception #5: Combustible materials fully enclosed within one of the following: part 5.3: Materials listed and labeled for installation within a plenum. As the term "insulation" is general, the material you choose needs to be specifically listed for use within a plenum. This listing/ information should be provided to the inspector at time of inspection. Nearly all product manufacturers will provide the technical data, and supporting documentation necessary.
Commentary
None.