bath fan venting question

Nov 13, 2007 13 Replies

I am putting in a bathroom in my basement and know I need to vent the fan. I plan on running the vent between the joists, but I'll need to jog around the i-beam. is it okay to use flexible dryer-vent type pipe to come down and then back up to get around the structural beam? Essentially it would look lik ~~~~U~~~~~~ where the U is the flexible vent pipe going underneath the beam? Other suggestions?



Thanks,



Yes you can use that flexible stuff. It will reduce the air flow somewhat, but not too bad.

Frankly I would use it on a vent fan long before I would use it on a dryer. It is double trouble when used on a dryer. First it reduces the air flow and therefore the efficiency of the dryer and it also catches lint that further reduces air flow and is a fire hazard. In the bath the lint is not much of a problem.

on 11/12/2007 8:34 PM snipped-for-privacy@gmail.com said the following:

That U might pose a problem if you vent it out the attic roof. Think P-trap. Even shower mist could condensate on the inner walls of the pipe and fill the U.

I'd use solid elbows and pipe cut to size. The flex will add more air resistance, the creases will catch dirt,lint and moisture and eventually probably corrode thru. If you have a good sheet metal shop in your area you can probably get an oval shaped pipe that would give you some additional clearance if you need it, or could use it to go above the beam.

I'm not planning to put a shower in the basement bath, just a toilet and sink. THerefore I'm not really worried about the condensation or reduced air flow since I'm only putting the fan in to meet code. I know that what I'm proposing is less than ideal, and if a significant amount of moisture really needed to be exhausted then I'd probably have planned it differently, but as it is, I just want to pass code.

Why not go the other way?

s

I might add that we have all avoided the code issue. Local codes are not all the same so you may want to check with the local code enforcers for a final word on that issue.

Which brings to mind the question: Why are lavatories required to have a vent?

To remove smells instead of having them go into the whole house and if there is a bath/shower, to remove excess moisture. I think in most places, the vent can either be a fan or a window, though I would always want the fan.

Slightly off-topic, but related. Do I need a vent for a utility sink in the basement? Is it recommended/required to install the utility sink inside the bathroom that has a fan-powered vent?

I think you need a sewer vent pipe, which is an entirely different beast.

Yes.

That is up to you. I don't think I would bother.

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