Water heater roof vent

I have a weird kind of leak. Water comes up through the cracks in the floorboards when it rains.
The subflooring underneath isn't wet. So I thought maybe it's coming from the roof. There's a water heater vent which goes through an interior wall, near that spot. I thought maybe rain is leaking down the side of the vent and spreading out onto a board at the bottom of the wall, and channelled along tongue and groove channels in the flooring.
But when I got up on the roof with a tar-gun, there weren't obvious leaks around the side of the vent. It would maybe leak a little (which I sealed off), but it didn't look too bad.
But, is the water heater vent supposed to have a cap on it? There's a strange 4-sided crinkly thing around the sides of the top, but no cap. I don't understand how, even if it were lacking a cap, water could get into the floorboards. I'd think that rain would go down into the water heater, if it were falling into the vent - not end up in my floorboards.
The vent for my gas house heater *is* capped, though.
What should the water heater vent look like?
thanks Laura
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I have a weird kind of leak. Water comes up through the cracks in the floorboards when it rains.
The subflooring underneath isn't wet. So I thought maybe it's coming from the roof. There's a water heater vent which goes through an interior wall, near that spot. I thought maybe rain is leaking down the side of the vent and spreading out onto a board at the bottom of the wall, and channelled along tongue and groove channels in the flooring.
But when I got up on the roof with a tar-gun, there weren't obvious leaks around the side of the vent. It would maybe leak a little (which I sealed off), but it didn't look too bad.
But, is the water heater vent supposed to have a cap on it? There's a strange 4-sided crinkly thing around the sides of the top, but no cap. I don't understand how, even if it were lacking a cap, water could get into the floorboards. I'd think that rain would go down into the water heater, if it were falling into the vent - not end up in my floorboards.
The vent for my gas house heater *is* capped, though.
What should the water heater vent look like?
thanks Laura
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Graven Water wrote:

I'm not saying that the water you described is coming from a leak from the water heater venting but . . . as for whether or not it is possible for rain to fall inside an uncapped vent and end up OUTSIDE the vent pipe connected to the heater, I think it's possible.
The vent piping is designed to exhaust heated gas UP, from lower to higher, without its leaking out. It is not necessarily designed to prevent fluid (gas or liquid) which is flowing DOWN, from higher to lower, from leaking out. The vent pipe sections connect to one another by overlapping, with the bottom (female) of the higher section(s) overlapping the top (male) of the lower section(s). If rain is blown into the vent, it can flow down the inside of the higher section(s) and end up flowing down the outside of the lower section(s). Once on the outside of a section, the water stays on the outside of lower section(s).
Is there any place (attic or basement) where you can see if that may be happening? If you can view (one of the) lower vent sections, you may be able to see vertical traces where water has flowed . . . or not.
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Erma1ina wrote:

So the water heater vent is definitely supposed to have a cap on it? I can probably get a new cap for it. It sounds like the kind of thing that might leak subtly for a long time and then get worse. There might even be right angles in the vent inside the wall. Anyway I can try capping it and see if the leak goes away.
thanks Laura
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"Graven Water" wrote

Laura,
Can you post a couple of digital pics of the roofing material surrounding the boot of the stack?
I wouldn't waste money yet, on buying a new cap. The cap you describe sounds similar to what I've seen. If water is getting into the vent, I don't see how it could find it's way back out b/4 it enters the heater.
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There are different designs but the cap should prevent rain from entering the vent pipe. Rain in the pipe can find its way onto the floor pretty easily.
Don Young
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It doesn't have a cap at all! It has a 4-sided crinkled piece of metal surrounding the sides of the vent pipe at the top. Maybe there was a cap long ago and the 4-sided thing was how the cap was mounted.
So yes, I got up there and sealed the outside of the vent, and I didn't think it looked like it would have been leaking much water, and then later I thought, maybe the real problem was staring me in the face - that rain is just falling into the (vertical) vent pipe.
Laura
Johnny writes:

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It *does* have a rain cap. My memory was deceiving me ... I got up there again and looked. Now I really don't know how water's getting into the floor, because it rained again and water's in the floorboards again, in spite of the sealing I did. I might look in the attic for clues.
Laura
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Is there a window on the wall above that part of the floor that's getting wet? Perhaps it is leaking.
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