Should semi-rigid duct for bath exhaust fans be expanded?

[KineticoUser]

Expanding the semi-rigid duct could reduce the friction by creating smoother walls, but limiting the expansion will make the duct more rigid and durable. I could expand it the full 8' and then cut it to the 4' I need or just limit the expansion to 4'. What are your suggestions? I'll also be insulating this duct after I connect the fan to the roof vent cap.

 

[Fitter30]

Flex duct? Look like this? Pull it snug. Stainless hose clamps for each end.

https://www.google.com/aclk?sa=l&ai=DChcSEwjw9IHx2aSFAxWtS0cBHXE0DIwYABAOGgJxdQ&ase=2&gclid=EAIaIQobChMI8PSB8dmkhQMVrUtHAR1xNAyMEAQYBSABEgIFffD_BwE&sig=AOD64_20P8KLcUo4QS0aA607nsId5R6VkQ&ctype=5&nis=4&ved=2ahUKEwip__rw2aSFAxXIg4kEHejLCOQQwg8oAHoECAsQDg&adurl=

 

[Sponsor]

 

[KineticoUser]

No, that's not semi-rigid. This is semi-rigid: semi-rigid duct

 

[Fitter30]

Want to cut expand long that aluminum after cutting has a tendency to unravel the cut edge. Just expand to the 4' can always pull it snug and cut it if needed.

 

[KineticoUser]

I figured it would stand up better if it wasn't fully expanded, but, as you see in this picture, people do suggest fully expanding it.

 

[KineticoUser]

This is being installed in an open space.