TinnerFlow
Grease Duct Systems ยท Grease Exhaust Systems

Grease duct through rated shaft

Fire-rated enclosure penetration

Life-safety system.
The approved design, adopted code, qualified procedure, and exact manufacturer instructions control this installation.
ConnectionWelded/listed duct plus rated enclosure
SupportIndependent structural supports

Before you start

  • Grease duct is a fire/life-safety system. Verify the approved design, adopted code, hood and fan requirements, listed enclosure or shaft details, and inspection hold points before fabrication or installation.
  • Confirm the rated shaft or listed enclosure assembly, duct clearances, supports, penetrations, access assemblies, firestop interfaces, and inspection sequence.
  • Use the approved tested or listed details for the exact wall, floor, shaft, and duct system.
  • Verify that supports are structural and independent of shaft walls and enclosure materials.
  • Coordinate aligned access openings through both the grease duct and enclosure.

Tools and materials

Grease-duct system, approved shaft or listed enclosure components, independent structural supports, compatible penetration and firestop components, listed access assemblies, layout tools, inspection light, labels, and manufacturer or tested-assembly instructions.

Lay it out

  1. Lay out duct, supports, shaft clearances, access doors, and floor or wall penetrations together.
  2. Keep the duct centered and prevent combustible construction or unrelated services from entering the required clearance zone.
  3. Sequence the work so grease-duct joints can be inspected before shaft or enclosure closure.

Set and support it

  1. Install independent structural supports before enclosure work closes access.
  2. Do not attach duct supports to shaft liner, fire-wrap, gypsum enclosure, or other nonstructural rated components unless the approved assembly specifically shows it.
  3. Maintain the required gap around the duct and penetrations.

Make the connection

  1. 1

    Install and inspect the grease-duct section and liquid-tight joint.

  2. 2

    Set structural support and verify the duct does not bear on the shaft or penetration.

  3. 3

    Install the approved shaft or listed enclosure components around the duct.

  4. 4

    Complete penetrations using the compatible tested or listed detail.

  5. 5

    Align enclosure access with the grease-duct access door.

  6. 6

    Inspect continuity at joints, corners, supports, and penetrations.

  7. 7

    Photograph and document the assembly before concealment.

Check the install

  • The enclosure or shaft is continuous and matches the approved assembly.
  • The duct remains independently supported and properly separated from shaft construction.
  • Access doors align and can be used for cleaning.
  • Penetrations and firestop interfaces use approved compatible details.
  • No combustible or unrelated material intrudes into the protected space.

Common mistakes

  • Treating fire-wrap, shaft liner, and field-built shafts as interchangeable.
  • Attaching supports to nonstructural enclosure material.
  • Closing the shaft before duct-joint inspection.
  • Misaligning enclosure access with the grease-duct door.

Stop and ask

Stop if the field condition differs from the tested or listed assembly, support attachment is unclear, access doors do not align, or a penetration detail is missing or incompatible.