Have to run a exhaust vent outside . The exterior joist is actually is 9-1/4 " wide.

Edited : Is it safe to cut a hole of 4-1/4" inch in rim joist and run a 4 inch vent pipe. the side is vynl.

The bathroom is in basement and is size of 5' by 7.5' which is small and the fan I have has 3" hose.

Please advise.

  • Why such a large hole for a 3” pipe? I would get a stick of 3” Are you talking about cutting a joist that is sitting on the foundation or a rim joist? That should not be an issue but other than that it would be two large. – Ed Beal Jun 17 at 14:28
  • Just edited to to let everyone knows, yes, the hole has to me make in rim joist. Are you saying cut a hole of 3-1/4" then ? is it enough to vent out ? – user137442 Jun 17 at 15:08

In a rim joist it should be no problem but I would make it a tight fit, check the size of your outlet it may be 3” so the pipe will slide over it.

I like the hole to be as small as possible I know the dryer vents I have installed for 4” pipe worked with a 4” hole.

I don’t care for the corrugated or flex pipe unless there are several bends and even then only for a retrofit. The sticks of 3” galvanized are only a few bucks but this is my opinion some don’t care about the stuff that builds up in the pipes but it can be nasty the straight sides don’t tend to collect moisture.

In my state we have to have a timer on bathroom fans to run after the lights are turned off this helps to dry out even corrugated pipe.

  • Thanks. I need only turn which could between to 60-90 degree. I found a Semi-Rigid Aluminum Duct. is that gona be OK ? – user137442 Jun 17 at 17:54
  • 1
    Those ducts that you twist to adjust the turn are so nice they make me wonder why some choose flex over rigid. But again that is my opinion. – Ed Beal Jun 17 at 18:37

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