Roof leaks only in extremely heavy rain

[Name Classified]

Hello,

I've been in my house 5 years, it was built in the 80s and my bedroom is on the top floor. In the past 6 months there have been two occurrences of extremely heavy rains and both times water seeped in at the top of one wall, bubbling up behind the paint. Many less severe storms in between did not cause the leak. However, I notice some old patchwork in the area that must have been done by the former owner. Here are some pictures:

area where the leak shows inside is somewhere between the end of the gutter and the exhaust pipe coming out of the roof, it is hard to judge exactly. The gutter itself looks pretty solid. Some of the caulk around the exhaust pipe was cracking so I replaced it, I don't think this was the cause. Does anyone have other ideas? Could heavy rain that falls right into the open pipe itself cause a problem? Should I be looking in another area? I know that once water gets inside it can move to another location before it shows itself. Has anyone experienced a similar situation? Thanks in advance, this group has always been a great help.

[dpb]

Start with getting into the attic and looking for signs there of where ingress occurred.

Inside the vent is not a problem; they're simply the vent stacks and are open to the drain lines so it just runs down the drain lines.

I'm presuming that your description of location on the interior wall is on a wall perpendicular to the eave outer wall and not along that wall and the distance referred to as that between the stack and the downspout? If it were the outer wall one would figure simply overflowing downspout capacity during heavy rains causing a backup/standing water getting under flashing.

If the seal around the vent stacks aren't good, that could be an issue; a good boot shouldn't need cementing.

See what it looks like inside first...

[Bubba]

There is a huge crack in the rubber boot around your vent pipe.

Don't f*** around trying to fix it with silicon, just replace it

[Evan]

That vent stack is in need of repair...

Generally they are not caulked around the pipe like that unless the rubber gasket boot has failed and leaked...

Replace the rubber gasket boot around the pipe, you can obtain a new one at a plumbing supply house...

You need to better indicate where the wall in question is, but it seems unlikely that the gutter is at fault -- water doesn't leak uphill where roofs are concerned... So unless the wall is along the exact line and parallel to the gutter, it is unlikely to be the source...

Look higher up on the roof, leaks can surprise you at how far downhill they will travel along the underside of the roof or down the roof joists before they drip down onto something to leak through...

~~ Evan