I’m renovating and have the opprtunity to vent my bathroom exhaust fans either through the roof or the soffit. The roof souns good because it’s the most direct path, but we do get snow here, so I’m not sure since the vent could get buried in snow. Could also go through the soffit, but then rising hot air could condense on the soffit. What’t the best way to go?
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Every roof penetration is a long term, ongoing opportunity for a leak. Andif it doesn't leak when you install it, perhaps it will in five years -- or fifteen.
Go for the soffits.
Check out FHB a couple of months ago. Mike Gurtin had a good article on this subject. Through-soffit ducting can be a problem if there are soffit vents that can draw humid air back into the attic. Otherwise, I'm with Yes'Mam about avoiding roof penetrations when possible. Insulate or use insulated duct to reduce condensation in cold weather. Someone here suggested putting a bend in the duct to catch condensate before it drips back into the fan.
Al Mollitor, Sharon MA
Always to the outside, never into the soffit connected to the rafter system. Particularly bath vent into the soffit creates high humidity areas that can be drawn up into the system, with its attendant rust, rot, mold, and deterioration potential.
how about a foot shy of ridge vent
In my county you cannot vent out soffit only gable or roof. My roof was brand new metal and gable was solit concrete, so I vented about two inches from ridge, couple months went by and while up in the attic I notice black mold all on the under roof plywood. Code says you can vent into attic as long as above insulation but reality out the roof is the only way. But it is legal to combine more than one bath vent into same pipe exiting roof. I have only two pentration, well, three counting the wood stove, but one sewer vent and one bathroom vent
Vent out the roof, that vapor is meant to go outside, not into your attic. Sealing stack pipes correctly will prevent any leaks. You can always vent out a attic gable wall. Good Luck
How would the stack pipe be protected from rain and downdrefts?
Where ever possible, I vent through the roof. I convert from that flexible junk to solid PVC, use a regular roof flange, and cap with an elbow to keep out rainwater. Also, avoid dips in the pipe, where condensation could collect. Long run? Use a system like FlowTec, where the fan sucks the odor out instead of blowing it a large distance. It's more efficient and quiet, too.When all else fails, use duct tape!
In my area (NW Ohio) naiingl the bathroom plastic vent off to a rafter just below a through roof vent works just fine. I've seen thousands like that without problems.
Results might be different in other climates.
Albert Einstein said it best:
“Problems,” he said, “cannot be solved at the same level of consciousness that created them.”
Your mileage may vary ....
go thru the roof.
get a good boot and install it correctly.
every nail hole could be a leak ... do it right and get on with life.
Jeff
Buck Construction Pittsburgh,PA
Fine Carpentery.....While U Waite
I'm convinced that going through the roof is the way to go, but I'm wondering what to put on the stack above the roof to keep rain and weather out, especially snow. It seems like a regular roof hat could easily get buried in snow. What goes on the end of the pipe?
There are special roof caps for 4" ducts. They have built-in flashing flanges, insect screens and backdraft flappers. Add a little ice and water barrier as you weave the shingles in with the flashing. Check out EFI.ORG. They have insulated duct, roof caps and great Panasonic fans.
Al Mollitor, Sharon MA