Vent Stack Leaking in Attic

[tbakbradley]

I have what I feel is an odd problem, and I've asked a few people that are not sure the answer. About a year and a half ago, my bathroom ceiling had a huge water spot on it. Went into attack and the Vent Stack coming down from roof was wet. I had someone replace the boot on the stack on my roof and that cleared it up. About a month ago, I had a new Roof installed on my house. A couple days later, it rained quite a bit. About three days after that, my daughter let me know that the bathroom ceiling stain was back and the wall drywall was bubbled up. I assumed roofers didn't seal the boot so called them, and they came out to seal it better. The wall bubble had settled down a little before they came out to re seal.

The next day, it rained quite a bit. Bubble back and i went up into attack and the Vent Stack from the roof was dry. HOWEVER, I have a big reducer to drop to a smaller PVC down to one bathroom. The other side of the reducer is a horizontal PVC to the smaller vent pipe down to the other bathroom. The leak were at the joints on both sides of the reducer to the smaller pipes (vertical down to one bathroom and at the horizontal pvc going towards the other bathroom vent). I dried all around it with a towel, but it was quickly wet and dripping again, at both joints. None of the Joints have glue, at least that I could see. I realize Rain Water can get into the Vent Pipe, but it was still dripping at these joints 4 days after the rain ??? A friend recommended some JB Weld, WaterWeld. I put that at both sides of the Reducer. I have not had any more drips since then and we've had a lot of rain.

What would cause this to drip water for 4 days after a rain (prior to the JB Weld)? I'm now wondering if I have some sort of blockage at the reducer, like leaves, and water collected, and was slowly moving down and dripping out the joints that had no glue? Now I wish I hadn't put any JB Weld on it as I could have removed the horizontal pipe and put some fish tape into the reducer to see if it was blocked.

Any ideas why I'd have drips at those joints when this is just a Vent Stack? It just seems too coincidental that it JUST started after the new roof was installed, but again, the vertical vent stack out of the roof is completely dry when it's raining.

 

[Diehard]

If you're in a pretty cold climate, I suppose some interior condensation could take place at that horizontal section and drip out that horiz. tee branch joint. Also assuming that horizontal pipe was not covered by insulation.

 

[tbakbradley]

This was happening when the temps were in the 80s. I've been in the house for 15 years and this has never happened. I do not have any insulation on the horizontal pipe that connects to the tee Branch and the vent stack to the other bathroom.

So would debris in the vertical stack or the Tee Branch joint be a possibility? That's the only "difference" I can think of. Since the JB Weld has sealed it to where there is no dripping out those joints now, should I move on, or continue to figure out why they were dripping when they never have before?

 

[Diehard]

Well so much for my shot in the dark.
I don't have a clue regarding the debris.
Any water in a vent line should drain back to a drain since it's required to be sloping back. So in the absence of any external water I would be apt to move on. Well maybe after I left a small catch pan under that horizontal pipe joint.

 

[tbakbradley]

I did put a catch pan just to be safe. But I can't where it's leaking from the bottom joint to the vertical pipe to the other bathroom. But all is good for now.

Speaking of the Horizontal Slope. I don't have good access to see by eye, and my long level is too long, and my small level may be too short. At some spots, it was showing level, while others, it was a very small slope. By small, I mean minimal. I need to get a level between the two sizes I have and check it. Good news is, the vertical pipe that the horizontal pipe is attached to has plenty of length that I could cut if off and hook it back up, so it would definitely be sloping downward to that vertical pipe. Before I do that, I'd like to know how much slope their should be.

 

[Diehard]

I did put a catch pan just to be safe. But I can't where it's leaking from the bottom joint to the vertical pipe to the other bathroom. But all is good for now.

Speaking of the Horizontal Slope. I don't have good access to see by eye, and my long level is too long, and my small level may be too short. At some spots, it was showing level, while others, it was a very small slope. By small, I mean minimal. I need to get a level between the two sizes I have and check it. Good news is, the vertical pipe that the horizontal pipe is attached to has plenty of length that I could cut if off and hook it back up, so it would definitely be sloping downward to that vertical pipe. Before I do that, I'd like to know how much slope their should be.

I agree with your approach.
Any chance to reference the pipe slope to a ceiling joist or ceiling? Of course you'd have to check that the joist, etc. were level.

OR...attach your short level to a piece of known flat bar, piece of wood, or whatever, with the required length.

EDIT: Actually, looking at your picture again, it looks like that's a sanitary tee on the left and with that smaller diameter pipe on the right, they create a low spot at that transition. Don't think a small slope would overcome that. Hmmm!

 

[Mikey]

My humble opinion is that horizontal section is no longer a vent, but a drain, and you're reducing from a 3" line to a 1 1/2" in a section that slopes about 1/4" per foot. Water is collecting in the transition, and without the fittings welded properly, that water is seeping out the downstream joint. It also looks like the final joint between the 3 x 1 1/2 and the 1 1/2 pipe is a little cockeyed (probably not fully seated), allowing it to leak even more. They should have done all the branches, etc., in 1 1/2" and made just one change from the 1 1/2" below to larger (if required) to go through the roof.