New construction and renovations in existing buildings to the plumbing and mechanical systems sometimes results in the installation of plastic drain, waste and venting in plenums that cannot meet the minimum flame spread and smoke density (combustibility) requirements of the mechanical code.

The plenum provisions of the mechanical code have been clarified to specify that any combustibles located within a plenum are required to be enclosed within a noncombustible raceway or enclosure, approved gypsum board assemblies, or enclosed in materials that are specifically listed an labeled for a plenum application.

The following two products are acceptable as a high temperature insulation blanket which is specifically designed and tested as a flexible enclosure for use on cables and on PVC, CPVC, PB, PE, PP, PVDF and ABS pipe in return air plenums:

• Fyre Wrap 0.5 Plenum Insulation manufactured by Unifrax
• Fire Barrier Plenum Wrap 5A manufactured by 3M

These products which must be installed in accordance with the manufacturer’s installation requirements will provide protection reducing external flame propagation and smoke generation for plastic pipes that are installed in ducts, plenums and other spaces used for environmental air.