Bathroom vent fan, overhead?

Old 04-12-02, 03:59 PM
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Question Bathroom vent fan, overhead?

We need to put a vent fan in a bathroom which has only a small window.
We plan on building in the attic at some point so I would prefer to put the fan in the wall which would vent directly to the outside, but have been told that that would not be as effective as an overhead fan ducted to the outside.

It's a not a big bathroom, maybe 6' x 10' and has a 10' ceiling.
I'd appreciate any feedback on the effectiveness of wall-mounted fans versus overhead

Old 04-12-02, 06:40 PM
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Mount the vent fan as high as possible on that 10' tall outside wall and you will be fine. As a total unit, it will probably be more efficient than a ceiling mounted unit. A wall mounted vent has a duct that is the thickness of the wall -- probably about 5". A ceiling mounted unit's vent is measured in feet. All of that extra ducting will reduce the effectiveness of the fan.

Now, you make a comment about doing some building in your attic at some point in the future. That may or may not be a possibility. How old is the house? If it has engineered trusses, your plans are pretty much DOA at your local bldg. dept. The only option would be to raise the roof and add another story. If the house is old enough that it has joists and rafters, (not the trusses), building in the attic may be possible, but there are a lot of code criteria that will have to be met -- ceiling heights, wall heights, floor joists sizes (they are a lot bigger than the ceiling joists you now have), window and egress requirements, ...

I see you live in S.F. I know what you are facing. The option of building OUT, rather than UP, is probably non-existent. If you sold the house tomorrow, you probably wouldn't qualify to buy it back.

These are some of the things you will be looking at, IF you opt to go with the addition.
Old 04-15-02, 09:43 AM
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Thank you Lefty!
Excellent point about the duct decreasing the amount of air passing through! It's a very easy decision now.

I know we're in for some fun when we get to the attic...but we don't have to worry about trusses. The bay area may be expensive, but at least we don't have to deal with snow

Also, from what I've gathered, if we make the attic room an "office" as opposed to a bedroom or other "living" space we have much easier codes to comply with.
Still, I have no doubt I'll have plenty of questions when we get started up there.

Thanks again

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