How to Hang Flex-Duct in an Attic

Flex ducts are commonly installed in attics as a quick way to connect main duct trunks to ceiling grilles. When flex duct lengths exceed 5 feet, the flex duct needs to be supported from a structural member, like a roof joist or roof truss, above. If the flex duct is not supported at the recommended span, the duct may sag or kink, which will restrict airflow through it. A duct hanger strap is useful for hanging the flex duct since it can be cut to any custom length.

Tape measure
Hanger strap
Cordless drill
Screws
Snips

Instructions

- 1
  Hold one end of the duct hanger strap up to the side of a structural member above the flex duct. Fasten the hanger strap to the structural member with two screws. The second screw allows for extra support. Avoid screwing to the bottom of a structural member, if possible, as a screw is more likely to pull straight out than shear off.
- 2
  Hold the flex duct at the desired elevation and wrap the hanger strap around it. Pull the strap up to the structural member and make a mark where you need to cut it.
- 3
  Cut through the hanger strap at the mark with your snips. Screw it to the structural member with at least two screws. If correctly done, the strap will take on a "U" shape with the flex duct resting in the cradle of the "U."
- 4
  Repeat Steps 1 through 3 to support the flex duct at least every 5 feet.

How to Install a Rotolock Compressor

How to Troubleshoot a Furnace Boiler Assembly

Heating & Cooling Repair