Bathroom exhaust fan vent flashing

[Jwhitman]

Last year, I had a new roof installed and the roofer installed the stack or vent flashing. I am not sure what it's called, but it's supposed to be used for a 4" bathroom vent. Now, I am attempting to install this vent duct and noticed it looks just like the one used to cover the vent pipe. What I am wondering is there suppose to be a pipe of somesort up into the flashing to direct the air out of the bathroom and to the outside.
Thanks,
J

[jimbo]

Your question is confusing, but there definitely must be a duct, usually 4" or 3" leading from the bathroom exhaust fan, up to a discharge point in the roof.

[JOHN_P]

The way the previous owners of our house had it, the duct from exhaust fan was kind of just tied up there below the roof vent (which to me seemed fine, maybe not perfect, but ok)

Well, last year I had the roof shingles redone, in the process of removing the shingles, apparently the duct work fell off from where it was rigged up, and this week I realize now that they ended up covering up the old duct hole altogether meaning that the bath fan was just venting into the attic, grrrrrr, yet another project I wasn't planning on...

Our other bath fan has a big rubber thing that's screwed to the underside of the roof, the duct from the fan gets connected to that. You're likely to find that piece at any home improvement store.

[jadnashua]

My vent exits through the roof. I have a low-profile vent hood that has it's own damper and flashing built-into it. The duct just goes through a hole that's under the vent hood and out. I opted for this, since I don't use the fan that much in the winter and snow wasn't an issue during the summer months when the humidity is high and the a/c is running! If it was snow covered, the heat would probably melt enough to allow it to exhaust. It's more normal to just have a pipe going through the roof, and it would be flashed just like any penetration - a flue, a plumbing vent, etc., that was sized for the OD of the pipe used.