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SNOW IN ATTIC FROM RIDGE VENT!

TOM_TURCI's picture

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It was just minor snow accumulation of approx. 1/2" deep in a 5x5 area on a plywood floor. Have the Honeycomb type ridge vent. Its been very cold in Connecticut and guess it blew up throught the ridge vent during a windy day. Wonder if the Mesh type ridge vent would of prevented this? HAS ANYONE EVER NOTICED IF THIS HAS HAPPENED TO THEM?Doesnt really leave me with a "warm and fuzzy" feeling.
What if the next day was pretty warm! A water deluge into my insultation! JUST CURIOUS.

THANKS, TOM TURCI

(post #170034, reply #2 of 8)

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We've studied vent performance at the University of Illinois. There is a great difference in snow exclusion of different ridge vent designs. You're right that the most effective snow excluders would be the mesh or filter types. Also, the vents that do a good job at excluding snow should also be expected to do a good job at reducing the air flow. There are many Breaktime threads on the importance (or unimportance) of airflow in attics.

In my opinion, keep out the snow and take it from there.

(post #170034, reply #4 of 8)

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You know, this is just a good example of "QUESTION EVERYTHING"!! Just because it is an accepted product that "everyone is using" doesnt mean it has been completely tested..always play the devil's advocate and use your own intuition and judgement. What a way to find out! At least it is an easily accessable problem, but only 2 years old. Maybe Ill contact the manufacturer and they can send someone out to fix it for me? Yeah right! Thanks for the input

tom

(post #170034, reply #7 of 8)

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It was just minor snow accumulation of approx. 1/2" deep in a 5x5 area on a plywood floor. Have the Honeycomb type ridge vent. Its been very cold in Connecticut and guess it blew up throught the ridge vent during a windy day. Wonder if the Mesh type ridge vent would of prevented this? HAS ANYONE EVER NOTICED IF THIS HAS HAPPENED TO THEM?Doesnt really leave me with a "warm and fuzzy" feeling.
What if the next day was pretty warm! A water deluge into my insultation! JUST CURIOUS.

THANKS, TOM TURCI

(post #170034, reply #1 of 8)

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Tom,

I don't know what the answer is but I'm glad you posted this. I always use cor-a-vent, the product you've got. I never knew this could be a problem.

Obviously, you'll want to do something to fix it but don't sweat the 1/2 of snow. That's only about .05" of water and that would not likely do much damage...this time.

There are heavy molded plastic vents that have several layers of baffles and the mesh together. I've always seen them as overkill but maybe not.

(post #170034, reply #3 of 8)

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Tom and Ryan,Ridge vents with baffles are the way to go in my opinion, if you are venting.The baffle will allow air to vent even in a fairly strong breeze but not allow wind blown snow to enter the vent.I use one from Lomanco (www.lomanco.com)and have been happy with their performance.Vince

(post #170034, reply #5 of 8)

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..........they liked the Company so much they bot it...

try Certainteed's Shingle Vent II...baffle, filter fabric...different colors... $2/ LF...
best air flow... no snow or rain....now you don't even need end plugs... they're built-in....

This one is a no-brainer...

IMHO

(post #170034, reply #6 of 8)

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I've seen snow (and dust for that matter) blow through some pretty unexpected places. When I see ridge vents I can't stop picturing the hood scoop of a 70s muscle car. In a good wind, you've got alot of hood space ramming a roof load of air straight up that ridge opening. I've looked at many ridge designs from huge framed up caps (a little too bulky for my tastes) to the slim line mesh and cor-a-vent styles (my asthetic choice). As someone said, the more you try to block the snow, the more you block the airflow as well.
Since I'm soon going to be reroofing my own home (and I believe ridge venting is a good thing) I'd like to hear opinions on some of the options I've been brainstorming.

1) (the easiest) Stick with a typical cor-a-vent method and build in a snow/water collection trough beneath the ridge in the roof space. Assuming the circulation within the roof space is a little more subdued than the storm raging outside, then maybe it's as simple as providing a safe place for the occasional blow in to land and evaporate.

2) Add a deflection shield (flashing) to redirect wind gusts over the ridge opening instead of head on. While great for ventilation, I can't think of a way to do this without creating what amounts to a rain trap or gutter along side of the ridge opening. Something tells me this would be worse than the original problem.

3) Use a half ridge vent. Instead of putting the vent square on the ridge, open to either side, place it only on the downwind side of the roof (assuming consistent prevailing winds). This option appeals to me. I can't totally block the wind on any one side, but half of my ridge faces an open field, and the other faces houses of similar size, so it stands to reason I'm going to get more blow in from the field. If I eliminate (or just solid fill) the ridge vent from this side, then maybe that will do the trick. Maybe this along with collection trough idea?

The garage on the other hand is getting a cuppola. So I guess I'll just wedge a sacrificial garbage can in the trusses underneath to catch what comes through.

Comments?

(post #170034, reply #8 of 8)

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Tom Turci. Few if any writers bother to tell us that not all combinations of ridge/soffit vents work. You don't say whose ridge vent you used.

One alternative to attic ventilation is to seal as tightly and carefuly as possible, the openings in the basement ceiling and the attic floor(see the archives on this), and beef up the attic insulation preferably with cellulose insulation. This substantially reduces the need for attic vnetilation, if not makes it unnecessary. GeneL.