Roofing/Plumbing Vent question

Old 01-25-07, 07:47 AM
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Roofing/Plumbing Vent question

Recently, I noticed that the shingles and waste stack flashing have a slight bow to them. We just put a new roof on my house as this area was leaking and the roof was close to needing replacement anyway.

So everytime there has been a rain more than a trickle, I've hauled myself into the attic (not an easy access) and crawled over to that are and checked for leaks. Even after 4 days of hard rain, no leaks (hooray).

I also put extra insulation in the attic shortly before we put the new roof on. This has helped tremendously as the only place snow melts is where this waste stack is, everything else is nice and uniform.

So here's where I evidently am retarded. Whoever was there before me added a half bath in the basement and ran a new vent up to the attic, it does NOT terminate through the roof and is 6" to a foot away from the cast iron stack that does go through the roof. I've never noticed the bugger before. I was up there at least 50 times before we did the roof and didn't notice it.

Anyway, it appears that this pipe is making the air nice and warm on the underside of the decking and causing condensation and, last night, frost on the underside of the decking. From what I understand this condensation is helping to cause the bowing shingles and could lead to ice dam formation and even more water issues.

When it warms up so I can walk around on the roof and what-not I plan on cutting a hole in the roof and venting it outside right and proper. My question is, as winter does not seem to be over, is there anything I can do in the meantime as a temporary fix to keep this from happening.

I was thinking something like running some PVC to one of the turbine vents or the passive vent that's already there. Would this help alleviate the problem for a month and half or so until it warms up enough to actually fix this right? I know these pipes are supposed to run vertical but would a 45 for a month and half be okay until I can fix it right?

Anything in particular tip-wise for when I DO run it through the roof? Man I feel like a total fool missing this thing when we could've vented it right whilst doing the damn roof.

thanks for the help.
Old 01-25-07, 05:08 PM
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It should be fairly simple to connect the vent pipe with your existing vent if they are closeby. I know how I'd do it if it was my house (cut off the cast iron pipe about 4 or 5' below the roof boot, use a rubber repair coupling to go from the cut off cast iron to PVC, tee in the new vent to the existing vent, and run new pvc back up through the existing boot)... but you should probably ask this question in the Plumbing forum to get an answer that would meet current plumbing codes.
Old 01-25-07, 07:56 PM
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I agree with XSleeper, but I've had to remove cast iron. It's not easy. Ask for how you can cut it nice and straight. The rest will be easy.

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