Help Vent Pipe Boot

Help! While having my house sided, the guys noticed that my vent pipe was missing through the roof. I had my roof redone about 2 years ago and some plumbing redone prior to that. I had noticed in the past the boot where the pipe goes through but alays thhought it didnt look right. turns out, it was missing. there was cast iron in the attic that ended about 2 incehes from the roof. how we were not gettting water no one knows, i guess it was dripping in the pipe, we werent getting any smells either because the plumbers didnt use any pipe hangers and the pipe filled with water. I ventured to the plumbing supply and they gave me 4" PVC, I took out the heavy cast iron and replaced it, i shoved it through the boot and connected it to the pipe leading to it. Today it rained like crazy and i have water drippng down the pipe, it looks like it is coming in around the seal of the pipe. was i supposed to caulk or cement it? please help!!! probably two years with no pipe at all seeing daylight and no water and now i fix it and it is leaking. your quick help is appreciated as it pours in my attic

If you push your pipe up through the pipe boot from below, then pull it down you will pull the seal down also.
This will result in the seal holding water until it inevitably leaks.
I don’t really know of a better way to describe it…

Well I can think of a couple x-rated ways… :smiley:

thanks, so how do i fix it? was i supposed to cement it or do i need to pull it back down and then push it back up again?

Well if this is in fact the case you can pop the seal back out.
Don’t use anything sharp that could cut the seal, I usually use a 16d framing nail.
Yes I have run into this before, too many times…
Stick the head of the nail between the seal and the pipe and just kinda work the seal back up, carefully.
Once the seal is turned up your job is done, sometimes it is easy sometimes it is not.

The seal should go up the pipe, like you put the pipe boot on from the top, and slid it down.

If this doesn’t work you can seal it with a high quality silicone, but try to pop the seal back out first.

thank you very much. i will try that tomorrow.

Was the outer diameter of the pvc pipe the same as the old cast iron pipe?

If it was narrower, then water will travel down the sides of it and drip inside.

If that is the case, you need a new pipe boot flashing.


unfortunately, i dont think the cast pipe was ever through the boot. is there any type of grease i could use on this seal to make it easier to fold under?

a picture would really help rite now.
you basically have to get the rubber seal tight around your pipe.