Wanted to start a new thread on getting a new roof installed, and was wondering what would be best for bath fan venting. Either the dampered roof mount type, I belive Broan makes a good one or the type that mount under the soffit. I’m located near Chicago, so we do get a fair amount of snow and the slope of the roof is 4/12. The runs to the soffit are not that far. Thanks for any feedback. -Ed
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Listeners write in about haunted pipes and building-science tomes, and they ask questions about roof venting and roof leaks.
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I ALWAYS try and avoid penetrating the roof.
With only a 4/12 pitch in Chicago, I'd be sure to find another route.
J. D. Reynolds
Home Improvements
Pp, Qq
Sidewall venting preferred. I've gone out through the roof (did so on my own house) with no problems using the Broan vent, but try to find another viable path before using the roof. The only time I vent thru the soffit is if the bathroom being vented is a half-bath, where steam is not generated in large quantities.
I have seen thru-roof penetrations that have survived years with no problems, even on 4/12 roofs.
"I am the master of my fate, I am the captain of my soul." Invictus, by Henley.
Any specific brand of vents that go up through the soffit that you guys have found work best?
I, also, try to avoid unnecessary roof penetrations, and if the duct goes vertically your much more likely to get condensation backdrainage and cold air backdrafts.
Venting to soffit works if there are no soffit intake vents for the roof. If there are, steam will get sucked up into the attic and cause havoc there.
Sidewall venting is the best route, but ideally the duct should drop 3' before going out so that condensate can drain outward and cold air cannot backsiphon.
Duraflo soffit exhaust vents would be my recommendation, if you go that route.
http://www.energyfederation.org/consumer/default.php/cPath/86_742_118
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
I'm pretty much in line with Nick's post.
Assuming your home has vented soffits, order of preference and why:
1) Sidewall - steam vents to open air; no roof penetration to potentially leak; no snow problems.
2) Roof - steam vents to open air; potential roof leak; snow considerations.
3) Soffit - no leaks; at least part of the vented steam will be drawn into the vented soffit and enter the attic potentially causing moisture problems there.
If your home does not have vented soffits, then a soffit vent from the fan will not cause any attic moisture problems.
Jim
Never underestimate the value of a sharp pencil or good light.
The trouble with soffit (or sidewall venting too close to the soffit) is that the moisture just gets sucked into the attic through the soffit vents.
In my area (NW Ohio) it works if you just nail off the exhaust duck immediately below a through roof vent. (At least, it's worked on the several thousand I've looked at <G>)
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