Dryer Duct Rated Assembly Membrane Penetrations

2021 International Building and Mechanical Code

The requirements of 2021 IBC Section 714 – Penetrations must be met.
Dryer ducts may be addressed per the guidance below with a detail signed and sealed by the engineer of record.

Code Reference

2021 IBC Building Code Section: 714 – Penetrations

Approved Methods for Dryer Duct Penetrations

1. Duct Wrap Method (Section A)
   The duct can be wrapped with a rated duct wrap from the point it enters the rated assembly to the point where it exits.
   • Must be listed and labeled for intended use
   • Rating must match the assembly (floor/ceiling, roof/ceiling, or wall)
   • Penetrations must be sealed to prevent smoke or flame passage
2. Tested Assembly Method
   If the assembly test report allows membrane penetrations by ducts, the dryer duct may pass through as specified.
   • Follow test report requirements
   • Dampers are NOT allowed
3. Engineering Judgment
   A letter from:
   • A Utah-registered engineer (passive fire protection expertise), OR
   • An IAS-approved testing agency
4. Relocate Membrane (Section B)
   Move the rated membrane so the duct is not within the assembly.
5. Chase/Soffit Method
   Enclose the dryer duct in a chase or soffit:
   • Outside the rated assembly
   • Within the same residential unit
   • Terminates at least 3 feet from openings or air intakes
6. IMC Compliance
   Dryer ducts must meet IMC Section 504 – Clothes Dryer Exhaust.

Details & Diagrams

Section A – Duct Wrap Detail

Includes:

• Fire-resistant-rated assembly
• Rated membrane
• Duct wrap at penetration
• Sealant at membrane interface

Section B – Membrane Relocation Detail

Includes:

• Continuous blocking
• Rated membrane above duct
• Unrated ceiling membrane below
• Duct fully outside rated assembly

Keywords

Horizontal assembly, fire-resistance-rated, fire resistant-rated assemblies