I noticed a leak on my bedroom ceiling and traced it to a drain ventilation system looping though my attic. It does not seem to be connected to the main vent stack. It seems to be leaking at an elbow joint.

The drain vent is PVC and I'm guessing is connected to my tub and washer drains and tied together in the attic.

My suspicion is that warm air traveling though the PVC is mixing with the cold attic air and condensating on the inside and dripping/leaking at the joint. Or else somehow water is getting into it.

My question is should I insulate the outside of the PVC or put some sealant on the joints? Any other theories as to why this vent is leaking water?

Perhaps the harsh attic temperatures cracked the joint sealant.

Thanks,
Kevin

I noticed a leak on my bedroom ceiling and traced it to a drain ventilation system looping though my attic. It does not seem to be connected to the main vent stack. It seems to be leaking at an elbow joint.

The drain vent is PVC and I'm guessing is connected to my tub and washer drains and tied together in the attic.

My suspicion is that warm air traveling though the PVC is mixing with the cold attic air and condensating on the inside and dripping/leaking at the joint. Or else somehow water is getting into it.

My question is should I insulate the outside of the PVC or put some sealant on the joints? Any other theories as to why this vent is leaking water?

Perhaps the harsh attic temperatures cracked the joint sealant.

Thanks,
Kevin

Rain water could be getting the vent. Replace the joint and the problem should go away.

Hi Kevin,

"I noticed a leak on my bedroom ceiling and traced it to a drain ventilation system looping though my attic. It does not seem to be connected to the main vent stack."
This bothers me. If it's not tied in to the roof vent then where does it terminate? Please explain farther.

"Perhaps the harsh attic temperatures cracked the joint sealant."
If the joint was proper primed and glued then the two surfaces melted and ran together making a weld. It's doubtful that the joint "cracked" because it got cold.

"My suspicion is that warm air traveling though the PVC is mixing with the cold attic air and condensating on the inside and dripping/leaking at the joint."
Good thinking but why just this one joint? If it's condensate all the pipes should be dripping, not just one joint. Run your hand up and down the pipe from the joint. Do you feel moisture on the pipes? If so it's the condensate on the pipes and not the joint.

"somehow water is getting into it."
You failed to tell us if the elbow was located on a vertical pipe or a horizontal one but if you had a faulty glue joint on the elbow and backfall on the line so rain water could collect and pool at the faulty joint then that would explain your leak. But that's kind of out there in left field. There could also be rain water entering at the roof flashing and running down the vent pipes.
I think I've explored all the possibilities but if I've missed any perhaps the other experts can pick up on it. Regards, tom

The ventilation line is indeed terminated at the stack pipe. My view was obstructed by heating duct work and insulation. The duct work runs horizontally directly over the ventilation line which is also running horizontally and separated by about 1 inch.

There are 3 vertical lines leading to our bathrooms and they connect to the horizontal; one T-joint in the center and 2 elbows at each end.

There is a leak at one of the elbow joints. The other joints felt fine as there was no evidence of water. I ran my hand on the outside of the PVC and there was no water felt anywhere else.

At this point it is either rain water going inside the stack pipe or condensation forming on the inside of the PVC and pooling at the elbow where the horiz meets vert. I'm ruling out the flashing and stack pipe leak only because it is too far away and many joints long the way.

In short, somehow the joint is faulty and needs to be replaced.

Thanks,
Kevin

"In short, somehow the joint is faulty and needs to be replaced."

Or repaired. Before you go through the hassle of cutting out the elbow why not try to patch the leak. Dry the area off good and prime the joint, making sure that primer got in all the cracks. Now slather on PVC cement so it gets in the cracks. Give it 15 minutes to set up and apply another coat of glue to the joint. Since the laeak isn't a pressure leak this should contain it. Good luck, Tom

Is there any condensation dripping off the heating ducts on to this vent pipe and making it appear to be leaking?

Tom,

Will it set properly in the cold attic?

Thanks,
Kevin

Lotta,

I was thinking of that too but there was no evidence of condensation coming from the heat ducts and dripping on the ventilation pipe as they are well insulated.

Now that I see this problem, I will be more vigilant looking for condensation sources several times a day and also during bad weather conditions.

Thanks,
Kevin

Tom,

Will it set properly in the cold attic?

Thanks,
Kevin


If the temperature's around freezing they make a cold weather PVC cement. Check it out at; http://www.tchristy.com/ColdCement.pdf
Good luck. Tom

If you are running the heating system, the ducts should be as warm or warmer than the air, thus, no condensation from them.

Follow Tom's directions.

Hi,

I saw this product at HD called QuickPlastik. It says it seals leaks for PVC, ABS, and CPVC plastic. It sort of works like play-dough. Is it for real or a waste of time?

The guy at HD said he didn't feel reapplying primer and cement would work.



Thanks,
Kevin

Hey Kevin,


"I saw this product at HD called QuickPlastik. It says it seals leaks for PVC, ABS, and CPVC plastic. It sort of works like play-dough. Is it for real or a waste of time?"
It sounds good. Why not try it and let me know.

On another note;

"The guy at HD said he didn't feel reapplying primer and cement would work."

Which is why he's working at Home Depot instead of for a plumbing company.

Think about it? Same plastic outside the fitting as inside. Same glue and primer. Now the manufacture tells us that when you prime and glue a PVC joint the plasric melts together and forms a weld. So priming and caulking a PVC joint with glue would,( using a bit of logic) tend to melt the PVC together to make a water tight joint. Now, I wouldn't siggest this repair on a pressure line but we are talking no pressure here. You don't have a pressure leak, simply a drip.
You can go at this any way you think best but I couldn't let the HD guy get away with a statement like that. Regards, Tom

"Which is why he's working at Home Depot instead of for a plumbing company.
"
:D

I felt the same way and took what he said with a grain of salt.

Since it is a low pressure link, I'm willing to give this quickplastik a try. My only hesitation is if it doesn't do the job, then removing itnmay be a pain.

Here is the link.

http://polymericsystems.com/PDF_Files/QuikPlastikTDS4023-0302.pdf

Anyway, I'll let you all know whether it works out.

Thanks Tom,
Keinv

As I said, listen to Tom. I am sure he has done it that way and it worked. The best answers come from people with experience in the area.