Originally Posted by Bama Rambler
A lot of the vent stacks aren't sealed to the roof. The vent cap seals to the pipe, but it's a good idea to seal the membrane to the pipe. I'd use some window and door spray foam and then run a strip of butyl tape around the pipe flared out onto the roof. Then I'd apply some lap sealant on top of that.
Then I'd install the cap over that and seal it up well.
Thank you for the tips. I tweaked it a bit. First sealedl roof to pipe with Eternabond, then Dicor around pipe, then butyl tape to bottom of vent cap, pressed cap down until butyl seeped out of sides a bit, trimmed edges, then Dicor in screw slots prior to setting screws, then Dicor to vent cap edges and over top. Yes, probably overkill, but I think that will do it and I can stop worrying about it.