Originally Posted By: Jon Keene This post was automatically imported from our archived forum.
I am in the process of changing my bathroom exhaust which was vented through the soffits. It was promoting ice daming in the area of the vent exit so I am going to vent it directly though the roof. My question is what if the best way to terminate the pipe through the roof. Let me start by saying I live in Maine where it is COLD and SNOWY in the winter. I have narrowed it to 2 methods to vent through the roof, but don’t know which is best and am looking for advice.
The first method is with a standard roof vent that is basically a covered 90 degree angled piece of metal with a screen and flapper on it. My concern with using this method is that it may cause ice daming at the point of exit with hot moist air blowing on a snow covered roof or having the exhaust get buried completely in snow and or having the damper freeze shut. Are any / all of these valid concerns?
The 2nd method is to run a straight piece of pipe up through the roof and extend is a foot or 2 above the roof and screen and cap it. My concerns here include moist air condensing on the pipe and running back down into the venting and/or freezing occuring in the pipe.
Anyone have any experience/thoughts on the best avenue to approach solving this problem. My goal is to only have to climb up on the roof once  and do it right the first time.
Originally Posted By: Guest This post was automatically imported from our archived forum.
If you vent it through an exterior wall, make sure it’s a good distance from the eave because all winter long the warm moist air will rise to the eave and condense there.
Originally Posted By: Blaine Wiley This post was automatically imported from our archived forum.
If you have a ridge vent, simply extend the duct to the ridge vent and terminate it there, in the attic.
Otherwise, the roof should be okay with the vent cover (we call them turtle vents around here). I saw both methods all of the time with no problems when I inspected in a cooler climate.
Originally Posted By: rcloyd This post was automatically imported from our archived forum.
I agree with Kevin. The best method of venting exhaust fans is through an exterior wall. One less roof penetration to develop a leak. Terminating the vent pipe at a ridge vent does not meet code. Code requires exhaust vents to terminate at the outside of the building.
Originally Posted By: aslimack This post was automatically imported from our archived forum.
Agree with Chad. If you don’t have a LOT of distance from the soffit area, the last thing you should do is dump alot of warm,moist air under an overhang with soffit (inlet) air venting. Asking for trouble in my climate.
Originally Posted By: charper This post was automatically imported from our archived forum.
Guys and Gals,
8 out of 10 homes I inspect have the bath vents terminating in the attic. Don't know what the builders where thinking or even how the county inspectors passed them. The inspectors here are expected to visit about 30 houses per day...They only have time to walk in and "spin" their heads and say ok.
Originally Posted By: Jon Keene This post was automatically imported from our archived forum.
I have been checking lots of web sites and help forums and there appears to be no “correct” answer to this issue. Solutions range from blowing it in the attic, to out the soffits, to out the ridge vent, to out an exterior wall, to out the roof. Common sense says the soffits and attic are horrible options, (even though that is what my electrician did and the building inspector let it go - which I found out afterwards is not to code in my town)
My problem with going through an exterior wall is the distance - about 20' horizontal run versus through the roof about a 3' run, (house is a full dormered cape with baths on the dormered side of the house.
If I did go through the roof, how would you reccomend I do it - what type of materials have you seen that work well - again remembering that I live in the cold and snowy state of Maine?
Originally Posted By: aslimack This post was automatically imported from our archived forum.
Jon, If i was doing it, i’d use the insulated flex duct to a hood on the roof. As little kinking of the flex duct as possible. Keep this in mind when installing the fan. You want to make sure it is positioned in a way that you don’t have to kink it too much to come back to the hood connection. Recommend clamping the connections to lessen the chance of tape loosing its adhesion and the duct disconnecting. If the cape is 50’s or so and hasn’t been redecked, you’ll have tounge and groove roof deck. Much more forgiving to moisture over a much longer time period than plywood wood be. You still want to take a peek now and then to be sure it’s securely connected. Minimizing kinks and insulated duct will also lessen the chance of condensation rolling back out the fan from the inside, making you think you have a roof leak.
Originally Posted By: ddivito This post was automatically imported from our archived forum.
I am troubled with the “code” references.
If you are inspecting new construction or know what your local interpretations of code are when the house was built then do not call it out as a defect or in need of repair unless it HAS caused a problem. I suggest we explain the possibilities of a vent ending in the attic or soffit and leave it at that if you feel you have to say something. Remember the “grandfather” clause.