Wind blown snow intrusion into attic?

[F451]

Hey guys,

Does anyone have experience with dealing with wind driven snow getting into attic spaces through roof vents?

I'm wondering if there are vents that are designed to prevent wind driven snow from entering attic spaces, while still allowing air flow. I'm researching online now but thought surely people here must have some knowledge about this they can share.

Last Saturday we had a snow storm with high wind gusts and a bunch of homes (over 20 and counting) in our neighborhood had snow accumulations in their attics resulting in drywall damage. One poor family had water dripping along their entire back wall, 30' of damaged area.

It appears that the snow primarily got in the attics through the roof vents, and possibly through unsealed gaps between the top of the walls and roof.

We were relatively lucky, it appears we only have damage in one area, we noticed a crack had appeared in the ceiling in the upstairs loft area. There is no access to that attic space (ridiculous) so I could not get up there to see how wet everything is.

We had a water damage repair company come out to assess yesterday, they will be back tomorrow to open up the ceiling and remove the wet insulation and further asses the condition of that part of the attic.

Any suggestions on how to prevent this in the future would be appreciated, thanks guys.

Ed

 

[F451]

Pic of the 2 vents that I am most concerned with, although I would like to replace all of them, or figure out some way to prevent snow intrusion (screen, plastic mesh in the vents?).

And I realize this isn't much snow for a lot of areas of the country, but the wind driven snow in the attics is a real problem for us.

Notice the one side of the street is relatively free of snow, the other side has drifts and accumulations. Our house is on the side with the drifts, those houses are on the top of a hill, just beyond our backyard is a sloped hill and from time to time we get hammered by easterly winds coming through the Snoqualmie Pass. 20 mph sustained winds, 40-50 mph gusts. The ridgeline houses acted like a windbreak, no snow in our backyards to speak of, large drifts in our front yards on the leeward side.

Digging out:

 

[fsae0607]

Not snow, but there's been a few times where we've gotten some heavy winds with rain and it's blown into my half dome style dormer vents. I have two in my garage and noticed a very small puddle beneath them after a bad storm like that.

 

[Firebrick43]

There is a product called GAF Cobra Snow country ridge vents, Not to hard to cut and retrofit in a current roof. Do you have soffit vents or gable vents? I have seen gable vents actually cause most of the issue not the roof ridge vents themselves.

 

[F451]

There is a product called GAF Cobra Snow country ridge vents, Not to hard to cut and retrofit in a current roof. Do you have soffit vents or gable vents? I have seen gable vents actually cause most of the issue not the roof ridge vents themselves.

Thanks. No gable roof ridge vents, just soffit vents and the turtle back style pictured above. The soffit vents have plastic screening on them.

The other areas of the attic, on the (eastern/windward side) that I could access did not have snow or water intrusion. No signs of it anywhere, double checked below the vents and along the soffit wall/roof connection area.

Its pretty amazing how much snow some people had in their attics. We also had a small amount of snow/ice that accumulated on the inside of one of the upstairs windows that was most exposed to the winds and snow.

It was so loud from the winds it sounded like the windows were going to blow out. I had to wear ear plugs to sleep, Lol.

 

[Firebrick43]

With the "turtle back vents" I have seen people put fine screen in them to help with wind blown snow. Problem is they plug up with dirt in just a few years and most never clean them out. As you found out the lee ward side is normally the point of ingress. The action of the wind over the roof cause the attic to have a lower pressure than out side and it ***** in the snow on the leeward side.

 

[finn]

My garage has a steel roof and a continuous roof cap, which lets a little snow and fragments of oak leaves accumulate on the attic floor.

I picked up a couple rolls of, I think, the GAF roof vent material that is normally used under asphalt roof cap shingles, and cut it to fit under the steel ridge cap.

The ridge still breaths, but the oak leaves don’t get in and I haven’t seen much snow in the attic.

 

[bdbecker]

I wonder if you have an imbalance between your intake (soffit) and exhaust (roof) vents. If you have too little soffit vent area for the roof vents, the roof vents will **** in air (and rain or snow) under certain conditions.

 

[F451]

Thanks for the input guys.

With the "turtle back vents" I have seen people put fine screen in them to help with wind blown snow. Problem is they plug up with dirt in just a few years and most never clean them out. As you found out the lee ward side is normally the point of ingress. The action of the wind over the roof cause the attic to have a lower pressure than out side and it ***** in the snow on the leeward side.

Thanks, that's what I'm thinking, if I put the screens or mesh up, then I have to maintain it. Not the end of the world, but just another thing to do, or worse, forget to do.

I wonder if you have an imbalance between your intake (soffit) and exhaust (roof) vents. If you have too little soffit vent area for the roof vents, the roof vents will **** in air (and rain or snow) under certain conditions.

Very possible. The houses in this cookie cutter development, 3 yrs old now, were thrown together. I battled the builders about the soffit vents in the area above the front porch/front door area (not the area with snow intrusion). I could put my arms completely into the attic space from the outside, no screening, no consideration about the proper sizing of the venting.

Basically left the entire area where the walls meet the roof open. They came back and closed the soffit vents up a bit, installed plastic screening, but I'm thinking if anything, the soffit venting is too much vs the roof top vents, but I really don't know anything about it. They weren't applying any math, industry standards to the venting situation what so ever, that I could tell. Just wanted to shut me up and be done with it.

Just going off how my prior homes were configured, the soffit vents were 2" or so holes drilled into the soffit area, usually 3 in a row, every 6' or so.

 

[F451]

Right now there's a homeowner riot revolt going on against the builders (large national company), we're supposed to have 10 yr warranty, but the builders have been doing everything in their power to do nothing, I mean NOTHING to help the homeowners with build warranty issues so far. They will generally ignore you until you threaten a lawsuit, then they'll send over a fly by night sub contractor to make the issue worse.

This time they're following the same routine, first citing the fine print, then saying its normal, then saying its an act of god. Latest is they were coming by yesterday, no show.

Meanwhile, they are advising everyone not to file insurance claims and that they will make everything right.

We're not waiting around, will see if we can recover any repair/abatement costs from the builder later. Will decide on insurance claim once we have a better idea on the costs, but I'm sure we'll be filing a claim. Don't expect to get any compensation from the builder, but we will see.

 

[Wrench97]

When I did my roof and wanted to install that type of vent the roofing supply house rep advised me against them citing snow intrusion as a issue.
He recommended and I went with a ridge vent instead.

 

[mobetta]

cheap *** builder using inferior products.

eve vents and ridge vents do the job best and really aren't hard or expensive to install

I did one tear off where the roofers just nailed up that style roof vent. NO HOLES in the sheathing, all for looks...I wonder why the shingles failed....

Unfortunatly Id say the fix is to eliminate those and put in a ridge vent.

 

[bdbecker]

...but I'm thinking if anything, the soffit venting is too much vs the roof top vents, but I really don't know anything about it. They weren't applying any math, industry standards to the venting situation what so ever, that I could tell...

As I understand it, too much soffit venting is usually not a problem (to a reasonable degree). Air takes the path of least resistance. If you have too much soffit venting, the worse case scenario is that your soffits may switch between being intakes and exhausts, which is a much more desirable situation than having your roof vents switching back and forth. Given the quality of construction you describe, I wouldn't be surprised if corners were cut in this area. Best of luck getting this resolved.

 

[kj_mustang]

If you can get to the bottom side of the vent easy and are able to put something up inside easily, they make a plastic mesh that is used on ridge vents to prevent bug and snow intrusion. looks like this.

 

[finn]

Right now there's a homeowner riot revolt going on against the builders (large national company), we're supposed to have 10 yr warranty, but the builders have been doing everything in their power to do nothing, I mean NOTHING to help the homeowners with build warranty issues so far. They will generally ignore you until you threaten a lawsuit, then they'll send over a fly by night sub contractor to make the issue worse.

This time they're following the same routine, first citing the fine print, then saying its normal, then saying its an act of god. Latest is they were coming by yesterday, no show.

Meanwhile, they are advising everyone not to file insurance claims and that they will make everything right.

We're not waiting around, will see if we can recover any repair/abatement costs from the builder later. Will decide on insurance claim once we have a better idea on the costs, but I'm sure we'll be filing a claim. Don't expect to get any compensation from the builder, but we will see.

Nothing ever changes. Had the same issue when we bought our first new house....in 1976.

A lot of it, in retrospect, is buyer’s remorse. You think you can believe the builder’s word, when, in actuality, it’s caveat emptor.

That’s why I never buy any sort of extended warranty. Not worth the fight. Just fix it and move on.

 

[Mainiac Mat]

FWIW...

Both my house and garage have grated aluminum vents under the eves and ridge vents running the length of the peak.

Never had snow blow in either.... and we get more than our fair share of the white stuff up here in Maine.

Never even heard of anyone getting snow in their attics.... but I also don't see that style of roof vent used in our corner of the country.

 

[docbach17]

If you can get to the bottom side of the vent easy and are able to put something up inside easily, they make a plastic mesh that is used on ridge vents to prevent bug and snow intrusion. looks like this.

Good solution... GAF makes some fine mesh stuff made for snow

 

[F451]

Thanks for the input everyone, appreciate it.

FWIW...

Both my house and garage have grated aluminum vents under the eves and ridge vents running the length of the peak.

Never had snow blow in either.... and we get more than our fair share of the white stuff up here in Maine.

Never even heard of anyone getting snow in their attics.... but I also don't see that style of roof vent used in our corner of the country.

Same. I grew up in northern NJ, 60's-70's, we used to get plenty of snow. I don't ever recall anyone, ever, getting snow in their attics.

Granted we did not have these types of winds back east. They're pretty fierce, I'm not kidding when I say it sounds/feels like the windows are going to get blown out. Ear plugs needed to sleep.

 

[F451]

If you can get to the bottom side of the vent easy and are able to put something up inside easily, they make a plastic mesh that is used on ridge vents to prevent bug and snow intrusion. looks like this.

Good solution... GAF makes some fine mesh stuff made for snow

Thanks guys, that's what I was thinking might be worth trying. I'd prefer a venting system that doesn't require any maintenance, needing to be cleaned periodically, will see what the builder says.

They sent a miscellaneous sub-contractor by yesterday to inspect the damage. Unlike the water damage repair company that came the day before, he did not have any special tools to measure moisture in the drywall. He did a quick inspection of the attic area, looked around outside. Did not do a room by room ceiling inspection.

I was not impressed, but it was in line with my expectations from the builder.

The water damage abatement company will be here this afternoon to clear out the wet insulation and further assess damage. They have been great to work with so far.

And they are SWAMPED with work, over 60 homes in the development (and counting) affected. Water abatement trucks all over the place, piles of insulation in garbage bags in driveways all over the place.

What a cluster.

At least we have power, water, etc. Could be worse.

 

[NUTTSGT]

I had an issue a few years back when it got cold, windy and the snow was very fine. It made it's way into the roof vents, piled up and then melted.

It would have been fine but it melted and dripped on a bookshelf I was making for the wife's office at work. . . . and I had put a coat of polycrylic on it. It left a big white (salt looking ) stain on the finish. She was fine with it but I was not happy.

I rolled up some coil stock or flat aluminum flashing and stuck it up in the vent to prevent it from happening again. It came back out in the Spring.

 

[csp]

My dad's old house had those turtle vents on the windward side of the roof and he had problems with snow blowing in. He would stuff them with insulation every fall and pull it out in the spring. Being in Colorado, it's dry enough to do that without worrying about condensation in the attic.

 

[F451]

My dad's old house had those turtle vents on the windward side of the roof and he had problems with snow blowing in. He would stuff them with insulation every fall and pull it out in the spring. Being in Colorado, it's dry enough to do that without worrying about condensation in the attic.

Good to know, thanks.

 

[F451]

The cleanup company showed up right on time yesterday, they did a good job, no mess left behind. They cut a 2'x2' or so opening in the ceiling, removed a 5'x6' section of wet insulation that was right over the small section of water damaged ceiling drywall. They did not see any signs of water intrusion beyond the 5'x6' area, checked the whole attic.

They put up a curtained off device to get air flowing through the attic, a couple of heater/blowers in the loft area, and a dehumidifier. Loud as hell, sounds like a jet is upstairs. They said 2-3 days with the equipment running 24/7 to dry everything out.

They will be back today to check on things.

The noise is really bad, I may have to take the puppy on an extended walk today. But feeling fortunate the damage was not worse, many neighbors have it way worse. And of course many folks across the country suffering without heat, electricity, and water, so really, can't complain.

Have heard nothing from the builder company, although wife reports the pitchforks are being sharpened up on Facebook, people freaking out. Can't blame them.

 

[Kaizen]

With that roof pitch and the wind blown pics I can see why. Can you move them to the back of the house? Soffit and ridge would be my choice followed by adding more to back of house roof and delete front ones. It’s gonna keep happening. That is clear.


Sent from my iPhone using Garage Journal

 

[jollygreengiant]

I'm wondering if there is something else going on? I live in the snowbelt of southwestern Ontario, and I see a fair number of houses with that style vent. A buddy of mine has that style on his house. I've never heard of people getting snow in the attic.

 

[couch67]

Not sure if you can get this type of vent in the US but they are common in Canada. Agree that moving the vents to the back side of the house might help.

https://www.homedepot.ca/product/maximum-sloped-roof-ventilator-model-301-black/1000168994

 

[lml999]

Meanwhile, they are advising everyone not to file insurance claims and that they will make everything right.

We're not waiting around, will see if we can recover any repair/abatement costs from the builder later. Will decide on insurance claim once we have a better idea on the costs, but I'm sure we'll be filing a claim. Don't expect to get any compensation from the builder, but we will see.

My first call would have been to an independent abatement company, the second to my insurance company. I would not let the builder anywhere near the house. Find your own contractor to fix the problem, let insurance pay for it, and maybe the insurance company will choose to go after the builder to reclaim some money.

It's your house. You have 100% of the interest in it. The builder has 0 interest in your house.

Oh, and while the contractor is there, I'd have them remove those turtle vents and cut in proper ridge vents. Here in New England, houses are expected to have matching ridge and soffit vents for proper air flow. We never see those turtle vents, which would not give the kind of air flow you want...

 

[toolmiser]

Wonder how many people have this problem and never know it. Unless it was really bad. How often do you ever go into your attic?

 

[F451]

With that roof pitch and the wind blown pics I can see why. Can you move them to the back of the house? Soffit and ridge would be my choice followed by adding more to back of house roof and delete front ones. It’s gonna keep happening. That is clear.

Sent from my iPhone using Garage Journal

Thanks, there are already the same style roof vents on the back of the house, the windward side, for some reason the attic in the back of the house did not get any snow driven in through the vents back there.

And can't delete the front vents, the attic area is split up into 2 separate spaces with the way the roof pitch is, they do not share air.

I think either ridge vents or the specially designed vents that don't allow wind driven snow intrusion are the way to go.

 

[F451]

I'm wondering if there is something else going on? I live in the snowbelt of southwestern Ontario, and I see a fair number of houses with that style vent. A buddy of mine has that style on his house. I've never heard of people getting snow in the attic.

I don't understand either.

 

[F451]

Not sure if you can get this type of vent in the US but they are common in Canada. Agree that moving the vents to the back side of the house might help.

https://www.homedepot.ca/product/maximum-sloped-roof-ventilator-model-301-black/1000168994

Thanks. Can't move the vents to the back, the attic space is seperated front/back due to the roof pitch. Idiotic design.

My first call would have been to an independent abatement company, the second to my insurance company. I would not let the builder anywhere near the house. Find your own contractor to fix the problem, let insurance pay for it, and maybe the insurance company will choose to go after the builder to reclaim some money.

It's your house. You have 100% of the interest in it. The builder has 0 interest in your house.

Oh, and while the contractor is there, I'd have them remove those turtle vents and cut in proper ridge vents. Here in New England, houses are expected to have matching ridge and soffit vents for proper air flow. We never see those turtle vents, which would not give the kind of air flow you want...

That is basically what we are doing.

Wonder how many people have this problem and never know it. Unless it was really bad. How often do you ever go into your attic?

Great question. Pretty much everyone out here is on Facebook, so word spread like wild fire once the first homeowner noticed water damage after the wind/snow storm.

I was actually going to check my attic before I heard the bad news as we had a leak around the furnace exhaust gasket through the roof previously. Gasket was replaced, no issues with it, but I wanted to make sure, plus I was curious if any snow got in the turtle back vents.

I was more concerned about the back, windward side of the attic, never occurred to me that it would get in on the leeward side.