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xrayman 02-29-2008 08:44 PM

leaking vent stack joint
I have perused this forum on many occasions, but this is my first post. Anyone have any idea why a joint in a vent stack in the attic might leak? The house is only 7 years old. The vent stack is PVC. The leak occurs at a 90 degree joint. From there the vent runs almost horizontal for about 15 feet then joins with another stack and up and out of the house. The leak is definitely coming from the joint and is relatively slow as first noticed a problem on the ceiling in my garage where I found mold growing. I took a section of the ceiling out to find more mold. I traced the problem to the leak in the attic. Thanks

Ron The Plumber 02-29-2008 08:47 PM

It happens, probably from rain water, just fix it.

xrayman 02-29-2008 08:49 PM

Can I just put sealer around the joint?

Ron The Plumber 02-29-2008 08:51 PM

You can try to add glue to the joint, might work, you won't know till the next rain.

biggles 02-29-2008 08:53 PM

those fittings slip inside the 90 just wipe the joint 360 around good and run some pvc glue around it,,mystery how the water is getting up the insert of the 90?

xrayman 02-29-2008 08:54 PM

I can get it to leak just by shaking it a little, think there is standing water in it?

xrayman 02-29-2008 09:04 PM

thanks for the help. I'm gonna get back up there tomorrow and try to seal it up

moneymgmt 03-01-2008 08:56 AM


Originally Posted by xrayman (Post 103156)
From there the vent runs almost horizontal for about 15 feet then joins with another stack and up and out of the house.

Are you certain its not a little less than horizontal? Wondering if enough water has built up in that pipe from rain/snow, then it gets heavy and pushes down harder on the far end of that 15', now its full of water? Can you get to the joint where it goes from horizontal to vertical through the roof? Try picking that up a bit and see if you hear/feel any drainage. If it is sagging just put a brace underneath it so there is always a slope.

xrayman 03-01-2008 09:35 AM

I'm heading up there now, I'll look at that as well, thanks

moneymgmt 03-03-2008 01:20 PM

any luck as to a solution?

xrayman 03-04-2008 04:23 PM

I got up there and put some epoxy around the joint. the horizontal pipe slopes down from the vertical towards the problem angle. As of just now when I checked, all seemed to be dry, and the mold clearing up. The pipe doesn't seem to have any water in it, which adds to the confusion as to why it leaks.

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