I’m installing a fan in the bathroom. There is a attic above so I’d like to go through the roof above the bathroom for the exhaust port. In Minnesota we have snow on the roof for at least a few months and this is the northwest side of the house so there is no sun to melt the snow. If the exhaust port gets covered in snow will it pose any problems? Any suggestions?
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The snow won't cause any trouble -- even if the outlet is covered with snow, it'll melt a pathway through after a minute or two of operation. However, avoid using a vent outlet with a flapper in it, as that can ice and freeze shut.
Insulate the duct well, to prevent condensation in the duct. Add an in-line flapper valve in the duct as close as possible to the fan/grille (the built-in flappers in standard bath fan units aren't that tight).
Consider using a duct fan (eg, one of the Fantech models) instead of the classical ceiling fan unit.
Thanks a lot for your advice I really appreciate it. I thought the air would melt, but wasn't sure. The in line flapper, never thought about that.
If you have eaves at the edge of the roof, you might want to consider using an undereave vent instead of going through the roof.
George Patterson, Patterson Handyman Service
Why wouldn't you use a vertical "roof jack" that sticks up above the roof 12" or so, which would be above the snow, right? Like the plumbing vents.
I simply don't like to make a roof penetration if I can avoid one.George Patterson, Patterson Handyman Service
George, have you done a lot of under-eave bath vents? I'm trying to decide to either cut the roof (DON'T wanna do) but I do already have an eave vent close by that I could use. You think that's as effective?
Thanks
You don't want to just run the fan duct to be close to an existing eave vent. You need to have the duct go through the eave and out, with an appropriate hood. And with some eave styles this is just about impossible to pull off.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Nope, but from what I've read about them, they look to be better than cutting the roof. I've always been able to run these things out a wall.George Patterson, Patterson Handyman Service
Edited 4/19/2007 10:13 pm ET by grpphoto
I'd like to thank all of you for your replies. About the only way I could run a vent out the side wall is to lower the ceiling. The top plate is less than 4 inches from the roof in the attic.
It is fairly common to lower the ceiling in bathrooms for this very reason.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
something I've done before is if there is a closet beside the bathroom
I go to the closet and cut an opening in the ceiling. The last time I did this I cut out the entire ceiling of the closet.This works on a low pitch roof with little or no attic space.I then place a step ladder in the closet and stand on it with my head in the attic and I reach over to the bathroom ceiling area to install the fan.when the fan is installed I close the ceiling by using plywood dropped down a couple of inches. Then I can get back up there if I need to.It's worked for me.^^^^^^
a Smith & Wesson beats four Aces
I just installed a Panasonic fan in my bathroom remodel.....super quiet.....and I have a solid state intermatic timer.....so I just set it and forget it.....it has 10, 20, 30 and 60 minute settings......
I live in Ontario and have 4 distinct seasons every year including plenty of snow. I totally avoid putting holes in the roof as much as possible except for plenty of vents near the ridge. I run bathroom exhaust to the soffit. Just to ensure that the soffit vents don't blow that humidity back into the attic I block the perforations for three feet each side of the exhaust on the hidden side or use non perforated there.
Running a four inch bathroom exhaust through your cold attic is an invitation to a problem.
Have a good day
Cliffy