Duct running for basement bathroom exhaust fan


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Old 07-20-03, 05:11 PM
U
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Duct running for basement bathroom exhaust fan

Hi-

Don't know if I should post this question in basements or bath, but since it involved drilling, I think this section might be best.

Anyway, I'm finsihing my basement and putting in a full bath, which will require an exhaust fan (no window) and running ducting from the fan between the overhead joists to the exterior of the house. I have lots of ducting between my existing overhead joists, so I only have one "channel" between the joists that will provide an easy path for the flexible ducting exhaust to run to the exterior wall.

When we removed the insulation from the inside of the exterior wall in order to cut a 4" hole to reach outside, we saw that the wood we would have to drill though is quite thick (looks like a header but I don't think it is), and it is actually the wood that the end of the joists are nailed to which in turn are supporting the floor overhead.

Am I allowed, per code, to drill a 4" hole into this piece of wood that the ends of the joists are nailed to so that I can vent this exhaust ducting to the exterior of the house? If I can't, how much of a "bend" is allowed in the bathroom exhaust flexible ducting in order for it to make 2 90 degree bends in order to get it to an area of the wall that is below this "thick wood?" Is there any code requirement as to how much bending one can do with this flexible exhaust ducting for a bathroom exhaust fan?

Thanks for your time in advance,
Steve
 
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Old 07-20-03, 05:23 PM
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ualdriver,

You are allowed to do what you are proposing. This is done all the time and not a big thing. A 4" hole through this does not infringe on the stability of the structure. What you are drilling through is called the rim joist. Take your time and it wil lwork out great for you.

It takes time and if you have a brick exterior, use a hammerdrill and drill a series of holes slightly larger than the duct vent. Then do the same with a long wood boring bit through the rim. If you go too large then get some caulk!

Hope this helps!
 
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Old 07-21-03, 08:07 AM
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Thanks!

Thanks for the info Doug! I'll be drilling through it today.....
 
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Old 07-21-03, 08:12 PM
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If it helps you feel any more comfortable, I'll second what Doug said about it being okay to drill through the rim joist. I will make one other suggestion, however, and that is to use rigid pipe rather than flexible pipe if you can. A straight run of 4" rigid pipe will ensure good air flow from your fan.
 
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Old 07-21-03, 08:52 PM
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Thanks

Thanks John
 
 

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