Need a 4" opening in my roof

Hi,
I am installing a exhaust fan in a bathroom and the only way out for the vent is through the roof. Can you point me to a resource that describes how to do that? I assume it's more complicated than putting some caulk around the edge... My roof is asphalt shingles.
Many thanks in advance!
Aaron
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On Mon, 26 May 2008 23:24:15 -0700 (PDT), Aaron Fude

ones below. Goo it in with roof cement, then stick the pipe through.
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On Mon, 26 May 2008 23:24:15 -0700 (PDT), Aaron Fude

Buy a vent cap type of assembly. They will have a door to keep wind from blowing back in on windy days, and a big flange you weave under your shingles. Once installed, you seal it down with roofing cement. You can usually find such kits with the vent hose included.
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Aaron Fude wrote:

Really?
When I had my roof re-done a few years ago the roofers took out the dryer vent (which went straight up from the center of the house), decked over the spot and put down shingles. I didn't realize the dryer was venting into the attic until some time later.
Anyway, I was faced with the same conundrum as you and was reluctant to put another hole in the roof.
I opted for about 30' of 6" PVC to run the vent to the closest soffit.
Here's a trick: Go UP into the attic about two or three feet, then a continuous slope downward to the soffit. That way, most of the fumes that condense will drain downhill.
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wrote:

If, that is, you can even get their. I must have one of the few houses in the world that doesn't have four inches of clearance between the top of the wall and the roof deck. The hole in the roof isn't a big deal; this is roofing, not rocket science.
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Chris Hill wrote:

Ah, okay. You can't go up and over. Could you maybe go down and exhaust the dryer into the sewer system? There's got to be a drain for the washer.
It's a JOKE, son.
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When I installed a composting toilet many years ago, part of the instructions included insulating the 4" PVC pipe. To help prevent condensate return, since the pipe went straight up and out.

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Here are a couple reasons you don't want to do this. For more, do a search on "attic dryer vent" and maybe add mold. There is a reason that venting the dryer, bathroom, or anything else directly into the attic is a code violation. Worst case, you could lose your roof--and I've read of it happening in only a few years.
http://www.remasinspections.com/images/BathroomVentMold.jpg
http://www.insightinspectionsllp.com/images/Im001811.jpg
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This link is to a bath vent kit you can get at the borg (aka HD or Lowes). The spec and installation sheet is available from this page.
http://www.broan.com/display/router.asp?ProductID $71
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i would try hard to vent it thru a eve or gable, the roof can cause future leaks
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Most roof leaks are indeed caused by roofs :-)
Yea I know what you mean though. I've never had anything leak so far that I've done - stacks, vents, plywood replacement, chimney flashing, wall flashing, and an entire 26sq roof with combos of everythig including valleys. With someone not too familiar with roofs, improper vent install (aka this outta be good enuf, or I didn't know that) is always a possibility. Also, just walking on a roof not knowing to look for nail pops, especially where you are stepping, can cause leaks.
Running out a gable can be much safer. But they still have to be aware of things like maximum code length, bends subtract from OA length, length reduces airflow, make sure there are no sags to collect moisture, insulating the hose may be necessary, and so on.
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BTW, you mean [eave] below the soffit? No concerns about the warm moist air rising and rotting the soffit over time?
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As soon as that hot, humid air is chilled by the cold in the attic, it will become condensate and return to the fan. I say take flexible line almost immediately toward the nearest eave, and after making the angle, transition to 4" Schedule 40, with a little bit of slope, and then at the eave, change back to flexible to go through the soffit. And put a 2x4 under the Schedule 40, propped up to maintain the slope, or the PVC will sag from attic heat in the summertime.

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