Re: plumbing vent
It's probably the flashing -- known as a "roof jack" -- around the vent pipe.
Unfortunately, the materials and methods for working on flat roofs aren't very friendly to the do-it-yourselfer. Your best bet is probably having a roofer come out and fix it.
P.S. -- Plumbers aren't qualified to fix roof leaks. I should know: I was a plumber once.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.