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Community and Q&A

Sealing a ridge vent

spup345 | Posted in General Questions on

My last post was a few years ago regarding foam insulation. I ended up getting open cell foam throughout the house and underside of the roof. Great decision and no issues. Even better decision vs closed cell for my purposes because it is water permeable so I could see roof leaks. Well, yesterday we had a noreaster and I noticed a leak. It’s directly under the far end of my ridge vent. We never had issues before so I’m 99% certain it was the 30mph winds ramming the rain into the ridge vent.

Sooo, given the insulation plugs up all my attic (soffits, roof etc), my ridge vent serves no purpose other than permit leaks during nor’easters.

Instead of paying $250-500 to hire a roofer to remove and reshingle the vent, is there an easier DIY way to plug it up? Spray foam may expand too much?

All suggestions are welcome.


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  1. GBA Editor
    Martin Holladay | | #1

    As a former roofer, I think there is only one answer. Sit on the ridge with your tool belt and remove the ridge vent. Then install new cap shingles or ridge flashing. Either (a) do it yourself or (b) hire a roofer to do it.

  2. spup345 | | #2

    Ok thanks

  3. christopherw | | #3

    I'm guessing that since you're using open cell, and my impression is that you don't have a vapor barrier on the interior, that you'd actually want a vapor diffusion vent. If you seal things off with something vapor impermeable, it sounds like you might be at risk for ridge rot.

    You may have something else in there to avoid this, but just in case, please make sure to consider the risk. Just sealing it off without taking this into account sounds like it could introduce some unintended consequences.

  4. spup345 | | #4

    Got it. So it sounds like I should almost leave the ridge vent to allow for vapor to escape (correct, no vapor barrier on the interior). Perhaps there is some other solution to prevent this rare wind blown occurrence? Maybe some sort of light foam insulation strips that are vapor permeable but at least will absorb and thus slow some of the water from having an easy and direct path into the interior? And then when the rain stops it will just evaporate. Of course if it’s freezing...or I just leave a couple of small Tupperware containers in the trouble spots where it drips since it rarely happens...

  5. treeguy147 | | #5

    George, Glad to hear that you like your open cell foam. If you don't mind me asking what climate are you in?

    I'm considering stuffing my ridge vents as well. I know that stuffing a material into the ridge vents isn't the right call for a lot of reasons. However, for my purposes this would be a temporary measure to see if a hot roof or vented roof is preferable. The building is currently unconditioned, uninsulated and unoccupied. There is a ridge vent but no soffit vents. it is a straight sloped 45 degree roof, no hips, valleys. 4C climate, so primary concern is moisture penetration. It is my understanding that moisture is 30x more likely to come through air penetration than vapor diffusion, as such air sealing is the first step.

    I found some air conditioner foam strips made of open-cell polyurethane on Home Depot's website. They are made by M-D Building Products. So my question to the experts is, would foam strips like these make sense for this application?

  6. spup345 | | #6

    I’m in NY just northwest of Manhattan. Looks like I’m in climate Zone 5 per the IECC

  7. spup345 | | #7

    FYI - quick update. Ridge vent is nfg w/ open cell (or any spray foam under sheathing imo), I'm having it removed/sealed (actually just getting entire roof redone). Stuffing it not the right way to solving this problem.

  8. Nola_Sweats | | #8

    It seems like open-cell foam sprayed under a ridge vent would act as a vapor diffusion vent. Yes, you can (and did) get wind-blown water through a ridge vent, foam or no foam. But if open-cell foam is vapor-permeable like a vapor diffusion vent, what's the difference?

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