Gable Attic Vents and rain

[bradne]

Twice in the last six months I have had rain blowing into the gable vent located on the south side of my house.   I have lived in this house for seven years and have never had this problem until lately.  Both times it was with heavy rains and high (50mph plus) winds.  It gets enough water that it is getting the ceiling drywall wet in my living room and bubbling/wrinkling the paint. 

The first time, I had two different contractors come in and inspect it just to confirm what I thought.  Both were unable to find any source of a leak but the spot is directly below the gable vent.   I chalked it up to a rare event, fixed the drywall and paint and forgot about it.  The second time (today), we had almost three inches of rain over the last few days with extremely high winds.  I was out of town so I was not here when it was occurring but discovered the problem when I got home.   I climbed in the attic and can see that the 2x4s that surround the gable are wet.  You can see where the water was running down the 2x4 to the top of the ceiling.  The vent is mounted securely and there are no cracks or other issues that I can see.   

I was wondering if any of you had a solution for this problem.  My initial thought is to make a sheet metal "shield" that would mount to the front of the exterior of the vent.  This vent is pretty inconspicuous so it would not be an issue.  I was thinking of taking a piece of galvanized sheet metal (painted to match the vent) the same height as the vent but about two inches wider.  I would "flex" the sheet metal and mount just the sides so that the sheet metal makes an arch protruding from the vent and leaves the top and bottom of the arch open allowing air to continue to flow, but blocking the wind driven rain.   

Am I overthinking this?  Am I restricting too much air flow?   I have three other gable vents in the attic along with vents in the edge of the roof.  I need to figure this out before I have more drywall damage. 

[BudgetSlasher]

I've never come across this problem, but a quick google turns up an on point This Old House posting that looks like it could address your problem.

https://www.thisoldhouse.com/ask-toh/gable-vent-baffle

[lthenderson]

Since this hasn't happened in the previous seven years, I'm guessing the diagnosis is off. My guess is that some part of the flashing between the siding and the outside surface of the gable vent has failed and not that rain has just started blowing in through the slats. I would guess there is some failed caulking on the outside of the vent that has dried up, cracked of fallen out. Once the water gets behind the flashing, then it could flow out onto the studs below the vent and down onto the ceiling. Another reason I think this is the correct answer is that if it were truly due to wind, I think you would see water in a larger area on the surface below the vent and just not running down the studs.

So my advice is inspect everything from the outside, especially where the siding meets the outside trim on the vent.

[EricEng]

This is a common problem with heavy wind+snow if the direction is just right as well.  Best solution is figure out which direction of wind is causing the issue and block off that side of the vent.  Lot depends on what style roof vent you have.  I used to get 1foot+ snow drifts in my attic through annoying roof vent systems.