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Roof leak near drain vent pipe

last year

A year ago, my bedroom ceiling developed a stain. Above it is 2' of attic with a drain vent pipe elbow, and above that is the roof. The attic is not accessible.

I checked from the roof and noticed that the rubber flashing around the pipe was deteriorated:

https://photos.app.goo.gl/UGueMwYsqzRqmApAA

I removed the old flashing and installed a new one with roofing tar sealant: https://photos.app.goo.gl/hHvRnheooB8TxZez8

A year later (a week ago), the ceiling got another moisture stain in the same place. I added a bunch more roofing tar sealant all around the vent pipe: https://photos.app.goo.gl/Eeqbirvg6BhYxc69A

A couple days ago, the ceiling started dripping in the same place during a long rainstorm. I checked the seal around the pipe and I don't see what's wrong with it: https://photos.app.goo.gl/Bnj6k7dw6Hi3RRSu8

Do you see anything wrong with it?

I theorized that maybe there's a leak inside the pipe at the elbow joint, so I did this experiment: I used a hose to run water down inside the drain vent pipe from the roof for 10 minutes and checked for moisture in the master bedroom ceiling. There was no apparent moisture.

Should I cut open a section of ceiling drywall and pull out the insulation and spray water on the roof and try to see how the leak is actually getting in?

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Comments (2)

3onthetree
last year
Hey Matt - that's a lot of cake frosting, and usually you don't want to do that, or you will be making yearly treks up on the roof to putty more on. I see you used DAP Roofing Sealant, which is asphalt based. You do not use that in contact with a rubber boot. It should be a poly or silicone.

They also make a "boot rain collar" that slides over the top of the pipe and covers the integral flashing boot.

Other than the original deteriorated boot and frosting, the continuing leak could be anything. The silicone dab on the 3 nails, the shingle cut too close to the metal boot, or something up higher than this vent penetration.
Matt thanked 3onthetree
Matt
Original Author
last year
Thank you! I'll try putting a permaboot over the whole thing and install silicone if needed around the nails at the base of the metal flashing boot.
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Wacokid, that's a good idea! I'm a little slow asking for help, sucks knowing how to do something but you body won't! Luckily I still have no order in the house or attic that I can smell. I also have a leak and while on the roof noticed a second vent pipe on the back of the house...I have no idea why its there, it must be from the old kitchen... But, the toilet has to vent some place and I'm sure its not that second one. I read dome place old homes like this one..1952 or so, vented through a chimney? We had one for the old oil furnace. Though, I'm thinking the broken one is for the toilet, and maybe the central air is keeping the oder down? Thanks for the ideas brother! Happy 4th!!!
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