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Red Squirrel 08-23-2010 12:18 PM

bathroom fan exhaust - roof or overhang?
 
What is the most common way to vent a bathroom fan? Is overhang considered acceptable?

Currently mine is in the overhang but it goes on my lower roof, causing ice damming. I can either vent it through the roof, or move it to another part of the overhang that wont affect the 2nd roof. (split level) It would be near a window though, so I'd just have to not open that window if the fan is on. Any code against this?


If I go with roof, what is best type of vent to use? It needs to be a couple feet high so snow does not clog it. I was thinking just using PVC pipe with a 90 degree bend, I see that on houses sometimes and it seems to me it's the most effective. Would need to add a screen so bugs can't get in. Think the screen would ice up and clog?

Mr Chips 08-23-2010 12:53 PM

Quote:

Originally Posted by Red Squirrel (Post 490003)
What is the most common way to vent a bathroom fan? Is overhang considered acceptable?

Currently mine is in the overhang but it goes on my lower roof, causing ice damming. I can either vent it through the roof, or move it to another part of the overhang that wont affect the 2nd roof. (split level) It would be near a window though, so I'd just have to not open that window if the fan is on. Any code against this?


If I go with roof, what is best type of vent to use? It needs to be a couple feet high so snow does not clog it. I was thinking just using PVC pipe with a 90 degree bend, I see that on houses sometimes and it seems to me it's the most effective. Would need to add a screen so bugs can't get in. Think the screen would ice up and clog?

Most people go through roof or sofit from what I've seen

I've always been told roof vent is best since warm air and water vapor will rise anyway. If you go through the sofit you run the risk of getting alot of that steam back up through the surrounding sofit. They make actual vent caps that have a flapper built in to keep out bugs and cold air

Red Squirrel 08-23-2010 03:26 PM

I kinda figured as such, will go with roof then.

If I've never done roofing is this something I should just hire out, or is it fairly fool proof to do it DIY. I understand the concept of flashing, I'd just have to read up a bit more on how to do it properly. This is an area I have to get right the first time or it could cost a lot in damages!

Mr Chips 08-23-2010 11:01 PM

Quote:

Originally Posted by Red Squirrel (Post 490097)
I kinda figured as such, will go with roof then.

If I've never done roofing is this something I should just hire out, or is it fairly fool proof to do it DIY. I understand the concept of flashing, I'd just have to read up a bit more on how to do it properly. This is an area I have to get right the first time or it could cost a lot in damages!

I'm like you, I hate the thought of putting any hole in a perfectly good roof, but everyone always says it won't leak "if you do it right", ( which to me is like saying " I would have won if I scored more points than my opponet....").

I recently helped a buddy do this, and it was a breeze ( always easier cutting someone else's roof) and to date has been water tight. get a proper vent cap, read the directions, and slap it on

kskier 08-24-2010 05:53 AM

Cutting a hole in the roof for a roof vent is pretty straight forward. You first go to a plumbing supply store and get a roof vent. They are better than the ones you can buy at Home Depot. Does your exhaust fan have a 4" vent, or 6"? Most come with a 4" hole, but some also come with 6". In some areas 6" is code. Once you get your fan located and installed........get into the crawl space and find the most direct line to the roof that is in between 2 roof joists. Try to avoid a 90 turn. If you have to make a turn, keep it at a min 45 even if you have to make 2 turns. The plumbing store sells metal flexible vent line and hard pipe. If you have a direct shot to the roof, use the hard pipe. Hard pipe is standerd duct work pipe in either thin gauge or heavy gauge.....you want the thin gauge. If you have to make a lot turns use the flexible metal. Don't use the plastic flexible line. Then drill a small hole in the center of where you are going to mount the vent. Then get a 4" hole saw and go on the roof and where you drilled the hole, put the center drill bit of the hole saw in that hole and drill thru the shilgles and plywood. After you get the hole drilled, you will have to pry up the shingle avove the hole. You might have to trim that shingle to fit around the vent. It is important that the shingle or shingles above the vent be on top of the base of the vent. You want to buy some roofing tar in a caulk tube and before you nail the vent dowm apply a good amount underneath the vent and on top of the vent underneath the shingles................done


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