What's the correct way to seal a flex duct connection (zip tie vs. metal band vs. tape/mastic)?

Plain-English answer

1. Pull back the outer insulation jacket and fiberglass layer to expose the inner plastic core sleeve. 2. Slide the inner core sleeve over the sheet metal collar at least 2 inches. 3. Secure the inner core to the metal collar using a heavy-duty nylon tension tie (zip tie) tightened down with an approved tensioning gun tool, or use a metal hose clamp. 4. Seal the joint with mastic or approved foil tape, then pull the fiberglass insulation blanket back over the connection and secure the outer jacket with a secondary zip tie or tape.

Field checklist

• Stop and verify the approved detail, manufacturer instructions, foreman direction, and project specs before touching it.
• Pull back the outer insulation jacket and fiberglass layer to expose the inner plastic core sleeve.
• Slide the inner core sleeve over the sheet metal collar at least 2 inches.
• Secure the inner core to the metal collar using a heavy-duty nylon tension tie (zip tie) tightened down with an approved tensioning gun tool, or use a metal hose clamp.
• Seal the joint with mastic or approved foil tape, then pull the fiberglass insulation blanket back over the connection and secure the outer jacket with a secondary zip tie or tape.

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