Working on the bathroom in a currently unfinished basement and installing a fan. I have 4" sheet metal duct to use, but I know it would be a lot easier to install flex duct. I have a straight shot of 30' out the back of the house (really tempted to go 5' out the front of the house, but it wouldn't look as good). Given a 30' straight shot, is there any reason I shouldn't use the metal duct (other than ease of installation)?


If you have the metal duct, there's no reason not to use it. Yes, flex duct would be easier but it would be more expensive, especially since you've got the metal duct already. There's also less resistance in the metal duct so your fan will do a better job.

  • 2
    With a straight shot I think metal is easier, and will have a better flow than flex+ , flex can collect moisture because of the higher resistance , stick with 4” or even 3” not enough flow allows moisture to build in the pipe.
    – Ed Beal
    Feb 8 '20 at 21:58

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