Need advice on roof vents

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Forum topic by D_Allen posted 04-21-2012 07:20 PM 1140 views 0 times favorited 4 replies Add to Favorites Watch
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495 posts in 2813 days

04-21-2012 07:20 PM

Hello all and thanks for your help.

I have a roof repair to do this spring and there are 2 bath vents that will need to be replaced.
One is the gravity flapper that was damaged when the new roof was installed and never did work correctly afterward. The other is above it and is the type that has an extended center. That one has allowed rain to get in when the wind blows over the ridge just right. I put on a piece of plexiglass that solved it but I want to replace it.
What kind of vents are the best to use for bath fan exhausts? Both are 3” on a 4/12 pitch.
Both have flaps on the fans so I don’t think I need the ones with flappers, just ones that will not allow driven rain to get into the vent.


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4 replies so far

View Mark Shymanski's profile

Mark Shymanski

5621 posts in 3742 days

#1 posted 04-22-2012 04:08 AM

Is the wind opening the flaps or just driving the rain in?

-- "Checking for square? What madness is this! The cabinet is square because I will it to be so!" Jeremy Greiner LJ Topic#20953 2011 Feb 2

View David Grimes's profile

David Grimes

2078 posts in 2669 days

#2 posted 04-22-2012 04:59 AM

Do not go through the roof. Terminate at your vented soffit. If you don’t have vented soffit, insert a vented section for this purpose.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

View D_Allen's profile


495 posts in 2813 days

#3 posted 04-22-2012 06:18 PM

The rain got past the one that is not a flapper type. I also had a leak this winter on the flapper type due to an ice dam just below it, probably because it was installed wrong.
The same roofing company put a 4” vent boot on a 3” ABS vent. They are idiots.
Venting to the soffit is not an option I want to use.

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View lashing's profile


111 posts in 2850 days

#4 posted 04-24-2012 04:42 AM

Everybody around here always says to go thru the roof. They say hot air in the soffit will try and go back into the attic and rot your fascia.

I have seen countless bathroom vents that go nowhere. Some old buildings have blocked vents for years with no issues, others will be spotted with mold everywhere. My 1974 house had every single one going nowhere and the fans completely covered in blown insulation. Nice.

What I really cant figure out is many hotels have no bath fan at all. So who knows? Seems no one but I certainly think going up and out makes sense.

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