Do you have a flashing boot on the penetration?

john:

Roof leaks can be very tricky and what is often thought to be a roof leak may be condensation dripping. Water can run a long distance before it finally drips.

Hi,
Yes, my exhaust pipe looks like what you show. What do you suggest ..... caulking around the boot?
Thanks,
.... john
P.S. My leak is near at the ceiling fan. Could a leak at the toilet exhaust be the cause of what I'm seeing?

Hi,
I have caulked all around the vent pipe boot, shown above, all of the roof vents on the side of the leak (4 of them), and I also found a couple of buckled shingles further up on the roof, that I also sealed. As of now, there is no water coming down the bathroom vent; but we really haven't had a good storm, so keep your fingers crossed. Thank you both for your help. I'll let you know if I have more problems.
.... john

You might be surprised. I had a leak in a light fixture for a year and my flat 3% built up roofing was perfect! "Water can run a long distance before it finally drips." Those are very very true words.

It was coming through the face of the block parapet, outside the roof area. 25 feet! If you can't fix it, keep looking in the most unlikely places you can (or can't) imagine.

And don't forget a sprinkler on a hose can be a very handy tool.