TinnerFlow
Grease Duct Systems ยท Grease Exhaust Systems

Grease duct fan curb connection

Roof exhaust termination

Life-safety system.
The approved design, adopted code, qualified procedure, and exact manufacturer instructions control this installation.
ConnectionWelded or listed fan adapter
SupportStructure-supported below roof

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 roof curb, fan inlet, hinge kit, fan listing, duct termination detail, weatherproofing, cleaning access, and structural support below the roof.
  • Coordinate fan service swing, electrical disconnect, roof membrane, curb height, and any listed adapter.
  • Verify grease cannot drain into the curb or roof assembly.
  • Stage the approved fan or curb adapter, supports, weatherproofing components, joint materials, and roof protection.

Tools and materials

Approved grease-duct fan or curb adapter, structural supports below roof, welded or listed joint components, hinge and service-clearance hardware, weatherproofing materials coordinated with roofing, level, marker, fall-protection equipment, and inspection tools.

Lay it out

  1. Mark the duct centerline through the curb and verify alignment with the fan inlet.
  2. Lay out below-roof support so the curb and fan do not carry the vertical duct weight.
  3. Confirm the fan can hinge or open fully for cleaning without hitting duct, conduit, or roof equipment.

Set and support it

  1. Install the structural duct support below the roof before making the fan connection.
  2. Protect the roof opening and membrane during installation.
  3. Hold the duct centered through the curb with the required clearance.

Make the connection

  1. 1

    Set the curb and fan components according to the approved roof and manufacturer details.

  2. 2

    Bring the independently supported grease duct through the curb.

  3. 3

    Install the approved welded or listed fan adapter connection.

  4. 4

    Complete the liquid-tight and weather-resistant treatment without trapping grease in the curb.

  5. 5

    Install and test the fan hinge or opening mechanism.

  6. 6

    Verify the fan opens for cleaning and the duct does not move.

  7. 7

    Complete roof and joint inspection before startup.

Check the install

  • The duct is structurally supported below the roof.
  • The fan opens fully for cleaning and service.
  • The connection is liquid-tight and the roof penetration is weather-tight.
  • Grease cannot leak or collect inside the curb or roof assembly.
  • Required clearances and access remain open.

Common mistakes

  • Letting the roof curb carry the grease-duct riser.
  • Connecting the fan before checking hinge swing.
  • Sealing the curb in a way that hides a grease leak path.
  • Allowing conduit or roof equipment to block fan cleaning access.

Stop and ask

Stop if the hinge kit, fan adapter, roof detail, structural support, weatherproofing method, or cleaning access is not coordinated and approved.